Crystalline
Water, Transmutation, & Machining...
http://www.nanotech-now.com/news.cgi?story_id=44551
February 22nd, 2012
Nanospire’s Cavitation Re-Entrant Jets Useful in
Micro-Nano Fabrication
Abstract: Nanospire has
announced that its investigative study on fusion created by
cavitation in water has come to an end. The company has been working
on high speed cavitation re-entrant jets and has acquired four
patents recently.
This technology can be used in sectors such as photovoltaics,
microsurgery, targeted delivery of drugs, micro/nano fabrication and
low cost extraction of algae for biodiesel production.
The founder and CEO of Nanospire, Mr. Mark. L. LeClair examined the
cavitation machining for jets in early 2004. He found a crystalline
form of water created by cavitation. The faceted jets had enormous
electrostatic charge. By applying electrostatic charge, the
crystalline jets etched lengthy semi hexagonal trenches which
resulted in increased removal of substances.
The crystals were accelerated due to their attraction towards the
supersonic bow shock produced by the Casimir Force. This
acceleration resulted in the relativistic speeds of crystals in
extremely short distances. This phenomenon was called the LeClair
effect. High elemental transmutation was witnessed due to the bow
shock.
Using the patented LeClair effect,
Mark LeClair produced a cavitation reactor in March, 2007. A hot
water heater was a result of the experiments carried out during
mid-2009, funded by a low energy nuclear reaction (LENR) advocate.
Mark LeClair along with Serge Lebid, co-founder of EVP and Five
Star Technologies, found that the reactor activated high
transmutation, fission and fusion in water. The reactor heated
2.9kW of water by utilizing 840W of input. The output was 3.4
times higher than the input. While passing through the reactor,
the temperature of water increased up to 32°F with temperature
spikes of 50°F. The experiment was repeated 12 times.
Dr. Edmund Storms, the LENR researcher, and U. Maine Orono (UMO),
Media Sciences of Oakland in New Jersey, conducted the elemental
analysis on the transmuted substances.The results from XPS analysis
showed that the glassy coating found on the reactor cores was
diamond. Thirty four elements including carbon to polonium were
identified using SEM analysis. The mass spectroscopy analysis
conducted on these samples by Shiva technologies in New York, showed
78 elements including lithium to californium and 108 isotopes from
7Li to 249Cf.
The findings of the study are expected to help solve natural
resource and energy issues. This cost-effective technology can be
used for industrial production of hot water at large scales for
commercial and residential purposes.
About NanoSpire Inc.
NanoSpire, Inc. is an IP holding company founded in January 2002, to
commercialize a new generation of cavitation reentrant jet-based
tools and processes. NanoSpire provides the first machine tool
capable of cutting, drilling, welding, hammering, and annealing
materials only a few nanometers in size by harnessing cavitation
microjets. NanoSpire has developed the next generation of high-shear
mixer based on its patented technology. NanoSpire has also developed
several advanced technologies for energy production.
Contacts:
Mark L. LeClair
Founder, President and CEO
mleclair@nanospireinc.com
Phone: 207.929.6226
Serge Lebid
Co-Founder, Executive VP
slebid@nanospireinc.com
Phone: 239.470.1996
Mailing Address
NanoSpire Inc.
25 Jesse Daniel Drive
Buxton, ME 04093-6565
http://www.nanospireinc.com/Fusion.html
Fusion
In February, 2004 Mark L. LeClair, CEO & Founder of NanoSpire,
Inc., discovered a crystalline form of water, while investigating
the machining potential of the cavitation jets under a Maine
Technology Institute (MTI) seed grant SG1424, Cavitation Machining
Prototype Development and MTI seed grant SG1803, Cavitation
Machining Product Development. The LeClair Effect behaviour was
again observed by Mark LeClair, Principal Investigator and Serge
Lebid (Co-founder & NanoSpire EVP), co-investigator, on a grant
from 2005-2006, Feasibility Study for Cavitation Nanofabrication
Technology for Oxygen Sensor Manufacturing. Other co-investigators
included faculty at Albany Nanotech, and members of Deloitte &
Touche, Cientifica and Sencer, Inc.. The grant was funded by the New
York State Energy Research and Development Authority (NYSERDA),
(Agreement #8250).
Produced by the enormous pressure of cavitation bubble collapse,
many of the jets were seen to have facets and to possess tremendous
electrostatic charge. The crystal
has an equilateral triangular cylinder subunit that most commonly
forms jet hexagon cross-sections. The crystal is a series of
repeating O-H bonds along its axis and is bound by hydrogen bonds
in the cross-sectional plane, a type of hybrid bonded crystal
known as a van der Waals crystal. The flexibility of the
hydrogen bonds allowed the crystal to assume a rich variety of
shapes, most commonly resembling a bacteriophage, with a large
hexagonal faceted head and narrow whip tail. The crystal tail can
split into a fractal fan on impact. The leading face closest to the
bow shock and the sides of the crystal are positively charged and
the tail is negative, allowing the crystal to form observed closed
loops. The positive charge of the leading face and sides was
revealed by impacting the crystal into litmus paper. This created
bright red hexagonal impacts in green litmus paper, and purple
hexagons in orange litmus paper, both indicators of zero pH and
large positive charge concentration on the crystal. The MTI grant
research showed that the crystallized jets would often carve long
trenches in materials guided by their electrostatic charge and
removed far more material than could be accounted for.
The crystal, moving at supersonic and greater speeds, is surrounding
by a bow shock like a fighter plane. The positively charged crystal
is attracted to its own negatively charged bow shock by the Casimir
Force and coherently extracts zero point energy on a large scale.
The crystal then accelerates to what appears to be relativistic
speeds in very short distances. This is implied by the heavy element
transmutation observed bull-dozed in front of the bow shock, the
only way these heavy elements are known to form in nature is either
from stellar core collapse or supernova explosions, both occurring
at relativistic speeds. The transmutation process observed in all
the experiments closely matched the behaviour of stellar fusion
nucleosynthesis and both type I & II supernova shock
nucleosynthesis. This discovery will have a major effect on stellar
evolution astronomy, allowing stellar nucleosynthesis, stellar core
collapse nucleosynthesis and supernova nucleosynthesis to all be
studied on a desktop, with varying compositions. The phenomenon of the water crystal
propelled by the attraction to its bow shock has been named the
LeClair Effect. Based on the Heisenberg Uncertainty
Principal, the LeClair Effect theory and the profound discoveries
based on it pose a serious quantum theory challenge to the classical
understanding of Newton’s Laws of Motion and the 1st and 2nd laws of
thermodynamics.
In March, 2007 Mark LeClair built and tested the first cavitation
reactor powered by the LeClair Effect, based on our patented
technology. More research was done from 2007 to 2009 with a variety
of other reactor designs that led to a series of key experiments
performed from July – August, 2009 under a grant, titled:
Utilization of Crystallized Cavitation Reentrant Jets for Zero Point
Energy Production. The goal was to produce a next stage hot water
heater reactor based on the LeClair Effect and was awarded by a
potential investor focused on promoting cold fusion. Mark LeClair
and Serge Lebid discovered that the scaled-up LeClair Effect reactor
was triggering intense fusion, fission and large scale elemental
transmutation using ordinary water. The 1.25” ID by 12” long reactor
produced 2.9 kW of hot water using only 840 watts of input, a
coefficient of performance (COP) of 3.4 times more energy out than
in. The water temperature was raised an average of 18 degrees C (32
degrees F) average passing through the reactor with 28 degree C (50
degrees F) temperature spikes observed. A total of twelve
experiments were performed, with 100% repeatability of the high
levels seen in excess heat and transmutation in the various
configurations.
Evidence of trenches generated by the passage of the water crystal
propelled by the LeClair Effect could be seen all over the reactor
cores. The positive crystal followed the induced negative charge on
the rows and columns of holes of the coiled perforated aluminium
plate that formed the reactor cores, with trenches usually going
tangent to tangent along the holes, orbiting the holes and also the
sheet edges, all guided by electrostatic attraction. Many of the
holes were progressively filled with transmuted material, transmuted
material also formed on the sheet surface. A uniform width melted
heat affected zone (HAZ) along each side of the crystal trenches
could be seen. The trench was disrupted at many points along its
length by millimeter-sized pits from the apparent triggering of
small supernova explosions, which also contained macroscopic amounts
of multicolored transmuted elements.
The large scale transmutation of elements was verified by three
separate independent scanning electron microscope elemental analysis
(SEM-EDAX) of the transmuted material, including University of
Maine, Orono Laboratory for Surface Science & Technology
(SEM-EDAX & XPS under contract), by courtesy of Media Sciences,
located in Oakland, New Jersey and by courtesy of well-known Low
Energy Nuclear Reaction (LENR) researcher and advocate Dr. Edmund
Storms, formerly of Los Alamos in New Mexico. The University of
Maine, Orono Chemistry Department also performed an analysis known
as XPS that measured nucleus binding energy, confirming that the
glassy coating seen covering much of the reactor cores was diamond.
The SEM analyses collectively detected a total of 34 elements
ranging from carbon to polonium. The same samples analyzed by
SEM-EDAX and XPS were also analyzed with laser ablative inductively
coupled plasma mass spectroscopy (LA-ICP-MS) by Shiva Technologies
(an operating unit of Evans Analytical Group) located in Syracuse,
NY. The more sensitive LA-ICP-MS detected a total of 78 elements
ranging from lithium to californium and 108 isotopes ranging from
7Li to 249Cf, a standard detection set that does not include all the
possible isotopes, but including all the stable isotopes and many
short and long lived radioactive isotopes. Together, the five
analyses showed that nearly every element in the periodic table was
detected in every type of transmuted particle in different
distributions, up to the limit of the LA-ICP-MS detection range,
californium.
The transmuted elements were
produced as chips up to one millimeter in size, in gram amounts
and clouded the clear polystyrene dishes they were placed in with
rings of nuclear tracks from the radioactive decay of short-lived
isotopes. The composition of the transmuted material followed the
same patterns as supernova nucleosynthesis, mostly carbon and
oxygen (like white dwarves) with decreasing amounts of the heavier
elements. The elemental distribution followed the saw-tooth shaped
astronomer’s odd-even rule, with even numbered elements occurring
in significantly greater amounts than the odd elements because of
the dominance of alpha particle fusion. The isotope ratios matched
those seen in both stellar and supernova nucleosynthesis. Many
radioactive extinct and non-naturally occurring elements were
detected, including isotopes of the transuranic elements. Most
importantly, all the rare earths, precious metals and many other
key elements were produced in high concentrations, greater than
typically seen in most naturally occurring ores.
The radiation emitted by the reactor left nuclear tracks, burned the
hole pattern of the core into the clear PVC core enclosure,
activated high neutron absorption cross-section 39Cl (56 minute
half-life) in the chlorine of the PVC core enclosure and transmuted
the water in the reactor into nearly all the other elements. The
experiment also accidentally resulted in acute radiation sickness
beginning the day after the August 25, 2009 experiments for both
investigators Mark LeClair and Sergio Lebid and lasted for more than
a year.
The discovery of the zero point energy based LeClair Effect
triggering fusion, fission and large scale elemental transmutation
by Mark LeClair and Serge Lebid was historic and could solve both
the energy and natural resource crisises. The LeClair Effect
explains excess heat and transmutation observed in electrolytic
cells (Pons, Fleischmann & others) and by hydrodynamic means
such as the Griggs pump or sonofusion (ultrasound), cavitation is
present in all of them. The current technology could easily provide
large scale production of hot water for residential, commercial and
industrial hot water at a capital and operating cost far lower than
fossil fuel, nuclear and other LENR-based technologies. NanoSpire is
currently seeking investors, licensees or joint venture partners to
accelerate commercialization and development of the technology.
US7297288
Method and apparatus for the
controlled formation of cavitation bubbles using target
bubbles
Inventor: LECLAIR MARK L [US]
EC: A61B18/26
IPC: A61B18/26 B44C1/22 A61B17/32
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to the formation and control of
individual micron size and submicron size cavitation bubbles for use
in nanofabrication operations. More particularly, embodiments of the
invention teach methods and apparatus for control of a re-entrant
micro-jet formed upon collapse of an individual or array of
cavitation bubbles and directing the impact of the micro-jet toward
a work surface or other objects with a high degree of precision.
2. Description of the Related Art
In general, the production of cavitation has been a phenomena many
have tried to avoid. Cavitation in a liquid is the formation,
growth, and collapse of gaseous and vapor bubbles due to the
reduction of pressure below the vapor pressure of the liquid at the
working temperature. Pump impellers, boat props, and similar
applications experience cavitation which can produce rapid damage
and erosion of surfaces. It has been well known for many years that
ultrasonic cleaning devices, which function by the creation of
cavitation bubbles, can produce significant surface damage to even
the hardest of materials. Studies by a number of authors have
revealed that one significant element in producing the damage caused
by cavitation occurs when a cavitation bubble collapses in the
vicinity of a surface, launching what is called a re-entrant
micro-jet toward the surface. This liquid jet can produce velocities
as high as 1500 m/s, and is capable of damaging the hardest
materials known.
Recently, a number of applications have been developed utilizing the
formation of cavitation bubbles through the use of laser light or
electrical discharge. Esch et al. (U.S. Pat. No. 6,139,543) and
Herbert et al. (U.S. Pat. No. 6,210,400) disclose the use of laser
light introduced into a catheter device for the purpose of creating
cavitation bubbles, whose expansion and collapse are utilized to
pump fluids in and out of the catheter. Hammer et al. (U.S. Pat. No.
5,738,676) discloses a laser surgical probe with a special lens
designed to produce the cavitation bubbles further from the end of
the fiber optics, to reduce the damage formed (presumably by the
re-entrant micro-jets launching into the lens on the end of the
cable). Such damage was also reported by Rol et al. in "Q Switched
Pulses and Optical Breakdown Generation. Through Optical Fibers",
Laser and Light in Opthalmology, Vol. 3, No. 3, 1990. Palanker (U.S.
Pat. No. 6,135,998) describes a method for performing electrosurgery
using sub-microsecond, high power electrical pulses are applied to
an electrosurgical probe interface. The tool described by Palanker
provides a cutting force by both the plasma generated by the
electrical arc and shock waves produced by collapsing cavitation
bubbles.
In each of the prior art references cited above, there has been no
attempt to control the direction and impact of the powerful
micro-jets formed upon the collapse of the cavitation bubbles
created when highly focused energy is introduced into a liquid.
Without such control, concern of collateral damage cannot be
avoided, especially when such tools are used in the human body in a
medical application.
Recently as well, there has been a significant interest generated in
the field of nanotechnology, for methods needed to fabricate micron
and submicron devices and nanomachines. There are very few
fabrication tools available that can cut, drill, peen, deform, or
otherwise modify features of a surface on a submicron to nanometer
scale. Much of the technology developed by the semiconductor
industry requires the fabrication of structures utilizing
photolithographic processing. This technology is not as flexible as
may be required, and will have certain difficulties when applied to
biological nanotechnology systems. Advancing the state of the art
required by nanotechnology applications will require fabrication
technologies operating at least 1 to 2 orders of magnitude below
that capable in the semiconductor process arena.
The invention as described in the above referenced provisional
application provides a method for the controlled formation of
individual cavitation bubbles comprising immersing a mask including
at least one aperture within a liquid, immersing a work piece having
a work surface in the liquid proximate to the mask, generating a
cavitation bubble proximate to the aperture such that the mask is
located between the cavitation bubble and the work piece. A
re-entrant micro-jet formed during the collapse of the cavitation
bubble is directed through the aperture to the work surface. An
apparatus for the controlled formation of cavitation bubbles as
described in the above referenced provisional application discloses
a mask having at least one aperture, immersed in a liquid, and an
energy source having an energy flow in the liquid sufficient to
create at least one cavitation bubble. The energy flow creates the
cavitation bubble proximate to the aperture and the collapse of the
cavitation bubble creates a re-entrant micro-jet directed through
the aperture to a work surface. While this technique is very useful
for processing surfaces that can be located conveniently in the
vicinity of a fixed orifice, there are many other situations where
one may wish dynamic, three dimensional control of the direction of
the re-entrant micro-jet. These situations may include eye surgery,
for example, where placing an orifice structure inside the eye may
not be practical.
The prior state of the art therefore has yet to provide a
fabrication technology capable of operating in the nanometer region
by harnessing the powerful phenomena of the re-entrant micro-jet
formed during the collapse of a precisely located cavitation bubble.
What is further needed is a method and apparatus to precisely
control the direction and location of the re-entrant micro jet
without the encumbrance of physical structure such an orifice
between the work surface and the cavitation bubble.
SUMMARY OF THE INVENTION
The present invention provides a method for the directed formation
of a re-entrant micro-jet including generating a working cavitation
bubble proximate to a work surface and generating a target bubble
between the work surface and the working cavitation bubble, wherein
a re-entrant micro-jet formed upon the collapse of the working
cavitation bubble is directed to the work surface.
An apparatus for the directed formation of a re-entrant micro-jet in
accordance with the present invention includes a first energy source
having an energy flow in the liquid sufficient to create a working
cavitation bubble proximate to a work surface and a second energy
source having a second energy flow in the liquid sufficient to
create a target cavitation bubble between the work surface and the
working cavitation bubble. The re-entrant micro-jet formed upon the
collapse of the working cavitation bubble is directed to the work
surface.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross sectional view of
an apparatus for generating target bubbles and cavitation bubbles
in accordance with one embodiment of the present invention.
FIG. 2 is a schematic view of a
collapsing, working cavitation bubble in relationship to a target
bubble in accordance with one embodiment of the present invention.
FIGS. 3a-3e are schematic diagrams
showing a sequence for directing a re-entrant micro-jet toward a
work surface through a target bubble in close proximity to the
working bubble in accordance with one embodiment of the present
invention.
FIGS. 4a-4e are schematic diagrams
showing a sequence for directing a re-entrant micro-jet toward a
work surface through a target bubble far from the working bubble
in accordance with one embodiment of the present invention.
FIGS. 5a-5e are schematic diagrams
showing a sequence for directing a re-entrant micro-jet toward a
work surface at an angle in accordance with one embodiment of the
present invention.
FIGS. 6a-6e are schematic diagrams
showing a sequence for directing a re-entrant micro-jet toward a
work surface at an angle, for working bubbles and target bubbles
in close proximity to the working surface in accordance with one
embodiment of the present invention.
FIG. 7 is a schematic diagram of a
working bubble and a target bubble directing convergent re-entrant
micro-jets to a work surface in accordance with one embodiment of
the present invention.
FIG. 8 is a schematic diagram of
three re-entrant micro-jets being directed at a movable work piece
in accordance with one embodiment of the present invention.
FIG. 9 is a cross sectional view of
a cylindrical pore in which the re-entrant micro-jet from a
working bubble directed through a target bubble are cutting a
cavity in the side wall of the pore in accordance with one
embodiment of the present invention.
FIG. 10 is a top view looking into
the cylindrical pore of FIG. 9 in accordance with one embodiment
of the present invention.
FIG. 11 is a cross sectional view
of a cylindrical pore where the re-entrant micro-jets from a
working bubble directed through a target bubble are cutting
multiple cavities in accordance with one embodiment of the present
invention.
FIG. 12 is a top view looking into
the pore of FIG. 11 showing multiple cavities formed at 90 degree
angles in accordance with one embodiment of the present invention.
FIG. 13 is a top view looking into
the cylindrical pore wherein a continuous slot has been fabricated
in accordance with one embodiment of the present invention.
FIG. 14 is a cross sectional view
of a cylindrical pore in where the re-entrant micro-jets from a
working bubble directed through a target bubble are cutting a
cavity at an angle not normal to the surface of the pore in
accordance with one embodiment of the present invention.
FIG. 15 is a schematic view of a
cavitation based process for injecting solution components into
lissome in accordance with one embodiment of the present
invention.
DETAILED DESCRIPTION OF THE
PREFERRED EMBODIMENT(S)
The control and direction of the re-entrant micro-jet formed during
the collapse of a cavitation bubble can provide a powerful tool for
performing various fabrication and manipulation functions at a
submicron and nanometer scale. A previous application (60/350,849
filed Jan. 18, 2002 entitled METHOD AND APPARATUS FOR THE CONTROLLED
FORMATION OF CAVITATION BUBBLES) describes how these re-entrant
micro-jets may be controlled through the use of an orifice placed
between the work surface and the collapsing cavitation bubble. While
the aforementioned techniques shall prove very useful for
fabrication processes where the work surface can be placed in
proximity to an orifice structure, there may be other applications
where placing such a structure will be difficult or impossible. One
example might be surgery inside the human eye, where a surgeon might
wish to generate re-entrant micro-jets in the humus by focussing
laser beams through the cornea. Another example might be to cut
features into the side wall of micron sized pores in an integrated
circuit structure where fabricating and placing submicron orifice
structures would be very difficult.
The present invention teaches a technique by which the re-entrant
micro-jet formed during the collapse of a cavitation bubble (working
bubble) can be directed by the creation of a target bubble within a
given proximity of the collapsing working bubble. Target bubbles can
be created in any direction in 3d space relative to the center of
the working bubble. All that is required is that there be a clear
line of sight (relative to the radiation source needed to create the
bubble) to the projected position of the target bubble, that the
target bubble is formed within a given time period of the collapse
of the working bubble, and that the target bubble be within a given
proximity of the working bubble. The target bubble serves to attract
the re-entrant micro-jet by creating a hydrodynamic condition
similar to that of a solid work surface or an orifice. However, the
target bubbles, unlike solid work surfaces, are transparent to the
jets, and allow the jets to slice through them unimpeded. Target
bubbles can therefore be used to direct the powerful re-entrant
micro-jets toward a work surface or object without the need for an
orifice. To be effective, a target bubble should be within
approximately 6 working bubble diameters of the working bubble. A
working bubble diameter is defined as the maximum diameter obtained
by the working bubble just prior to collapse.
FIG. 1 is a cross sectional view of an apparatus 100 for generating
target bubbles 102 and cavitation bubbles 104 in accordance with one
embodiment of the present invention. A work piece 132 is placed in a
container 134 filled with fluid 130. Components 108, 116, 118, 120,
124, and 138 make up the focussed laser device for creating the
target bubble 102. Components 106, 110, 112, 114, 122, and 136 make
up the focussed laser device for creating the cavitation working
bubble 104. The lasers 106 and 108 may be chosen from among the
group of CO2, Nd-YAG, dye, or excimer types. Other focussed energy
devices such as x-ray and electrical discharge electrodes may also
be used to create bubbles 104 and 106, as is well known to those
skilled in the art. Alternatively, target bubbles 102 may be created
by sparging gas though nozzles and orifices, and allowing them to
rise through the fluid proximate to the working bubble. Radiation
produced by laser 108 is collimated by lens components 116 and 120
and focussed distance 128 by lens 124. The intense laser radiation
focussed into a small control volume vaporizes the liquid in that
volume and creates the cavitation target bubble 102. In like manner,
laser 106 and lens components 110, 114, and 122 create the
cavitation working bubble 104 at a distance 126. Re-entrant
micro-jet 140 is formed upon the collapse of the working cavitation
bubble 104, and is attracted through target bubble 102 to work
surface 132. By altering the angular orientation of lasers 106 and
108, and the focal distances 126 and 128, the re-entrant micro-jet
can be positioned to impact anywhere on work surface 132. By
altering the distance of the working bubble 104 to the work surface
132, the impact force of the jet may also be altered. To be
effective in directing the re-entrant micro-jet, the target bubble
should be approximately within six (maximum) working bubble
diameters of the working bubble. The fluid in tank 134 can be any
fluid that absorbs the laser radiation being utilized, but is
preferably water or solutions containing water. The fluid may be
re-circulated and filtered by additional pumps and components (not
shown) to maintain an appropriate optical clarity.
FIG. 2 is a schematic view of a collapsing, working cavitation
bubble 150 in relationship to a target bubble 152 in accordance with
one embodiment of the present invention. As previously stated,
distance 156 should be approximately less than six maximum working
bubble diameters. To attract the re-entrant micro-jet formed as
bubble 150 collapses, target bubble diameter 158 should be greater
than approximately 10% of the maximum working bubble diameter. The
projected path of the re-entrant micro-jet is shown by dashed line
154. Inwardly directed arrows 160 in bubble 150 illustrate the
beginning collapse of the outer bubble surface. Concave surface 162
is indicative of the direction toward which the jet will be
launched. Target bubble 152 may also be a cavitation bubble in an
expanding or contracting state, as long as its diameter meets the
minimum criteria stated above as working bubble 150 begins to
collapse.
FIGS. 3a-3e are schematic diagrams showing a sequence for directing
a re-entrant micro-jet toward a work surface through a target bubble
in close proximity to the working bubble in accordance with one
embodiment of the present invention.
FIG. 3a shows a target cavitation bubble 202 formed in close
proximity to a working cavitation bubble 200. Both bubbles are
initiated at approximately the same time, the arrows emanating from
the surface pointing outward illustrate an expanding condition for
each bubble. The target bubble 202 is placed between the working
bubble 200 and the work piece 204. In this example; the target
bubble 202 is within six working bubble diameters of the working
bubble 200, and is also within six target bubble diameters of the
working bubble 200. The working bubble 200 is greater than six
working bubble diameters from the work piece 204. As illustrated,
the target bubble 202 is smaller in diameter than the working bubble
200.
FIG. 3b shows the working bubble 206 and target bubble 208 at their
maximum expanded diameters, just before they collapse.
FIG. 3c shows both bubbles 210 and 212 beginning to collapse, as
illustrated by the inwardly directed arrows on their outer surface.
FIG. 3d shows the initial formation of the re-entrant micro-jets 216
and 218 by each of the bubbles 214 and 220, respectively. Due to
their close proximity, opposing jets are launched from each bubble
toward each other.
FIG. 3e shows the net effect of the re-entrant micro-jet 224
launched through the target bubble 220, 226 to the work surface 228.
Since the working bubble 222 was initiated as a larger bubble in
comparison to the target bubble, the re-entrant micro-jet launched
from it (222) is dominant, resulting in a jet directed toward the
work surface. However, the impact force imparted by jet 224 is
reduced by the opposing interaction of jet 218 (launched from the
target bubble 220, 226) on the initial jet 216. This phenomena may
be utilized to moderate and control the impact force imparted by jet
224 on the work surface 204. The closer bubbles 206 and 208 are in
maximum diameter, the lower the net force delivered to the work
piece 204.
FIGS. 4a-4e are schematic diagrams showing a sequence for directing
a re-entrant micro-jet toward a work surface through a target bubble
far from the working bubble in accordance with one embodiment of the
present invention.
FIG. 4a shows a target cavitation bubble 202 formed in moderate
proximity to a working cavitation bubble 200. Both bubbles are
initiated at approximately the same time, the arrows emanating from
the surface pointing outward illustrate an expanding condition for
each bubble. The target bubble 202 is placed between the working
bubble 200 and the work piece 204. The working bubble 200 is greater
than six working bubble diameters from the work piece 204. In this
example, the target bubble 202 is within six working bubble
diameters of the working bubble 200, but is greater than six target
bubble diameters from the working bubble 200. As illustrated, the
target bubble 202 is smaller in diameter than the working bubble
200.
FIG. 4b shows the working bubble 206 and target bubble 208 at their
maximum expanded diameters, just before they collapse.
FIG. 4c shows both bubbles 210 and 230 beginning to collapse, as
illustrated by the inwardly directed arrows on their outer surface.
FIG. 4d shows the initial formation of the re-entrant micro-jet 216
by bubble 214. Since target bubble 232 is further than six target
bubble diameters from bubble 214, it does not "sense" (fluid
mechanically) the presence of working bubble 214 and therefore will
not launch a jet in its direction. However, target bubble 230 is
within six working bubble diameters of bubble 214, attracting the
re-entrant micro-jet from collapsing working bubble 214.
FIG. 4e shows the net effect of the re-entrant micro-jet 224
launched through the target bubble 226 to the work surface 228. The
full force of the re-entrant micro-jet formed upon the collapse of
the working cavitation bubble is applied to the work surface 228.
FIGS. 5a-5e are schematic diagrams showing a sequence for directing
a re-entrant micro-jet toward a work surface at an angle in
accordance with one embodiment of the present invention.
FIG. 5a shows a target cavitation bubble 202 formed in moderate
proximity to a working cavitation bubble 200. Both bubbles are
initiated at approximately the same time, the arrows emanating from
the surface pointing outward illustrate an expanding condition for
each bubble. The target bubble 202 is placed between the working
bubble 200 and the work piece 204, situated to direct the re-entrant
micro-jet from the working bubble 200 at an angle to the surface of
204. The working bubble 200 is greater than six working bubble
diameters from the work piece 204. In this example, the target
bubble 202 is within six working bubble diameters of the working
bubble 200, but is greater than six target bubble diameters from the
working bubble 200. As illustrated, the target bubble 202 is smaller
in diameter than the working bubble 200.
FIG. 5b shows the working bubble 206 and target bubble 208 at their
maximum expanded diameters, just before they collapse.
FIG. 5c shows both bubbles 210 and 230 beginning to collapse.
FIG. 5d shows the initial formation of the re-entrant micro-jet 216
by bubble 214. Since target bubble 232 is further than six target
bubble diameters from bubble 214, it does not "sense" (fluid
mechanically) the presence of working bubble 214 and therefore will
not launch a jet in its direction. Target bubble 230 is within six
working bubble diameters of bubble 214, attracting the re-entrant
micro-jet from collapsing working bubble 214.
FIG. 5e shows the net effect of the re-entrant micro-jet 224
launched through the target bubble 226 to the work surface 234. The
full force of the re-entrant micro-jet formed upon the collapse of
the working cavitation bubble is applied to the work surface 234, at
an angle 236. In this manner the target bubble may be used to direct
the jet in any suitable angle with the work surface.
FIGS. 6a-6e are schematic diagrams showing a sequence for directing
a re-entrant micro-jet toward a work surface at an angle, for
working bubbles and target bubbles in close proximity to the working
surface in accordance with one embodiment of the present invention.
FIG. 6a shows a target cavitation bubble 202 formed in moderate
proximity to a working cavitation bubble 200. Both bubbles are
initiated at approximately the same time, the arrows emanating from
the surface pointing outward illustrate an expanding condition for
each bubble. The target bubble 202 is placed between the working
bubble 200 and the work piece 204, situated to direct the re-entrant
micro-jet from the working bubble 200 at an angle to the surface of
204. The working bubble 200 is less than six working bubble
diameters from the work piece 204. In this example, the target
bubble 202 is within six working bubble diameters of the working
bubble 200, but is greater than six target bubble diameters from the
working bubble 200. As illustrated, the target bubble 202 is smaller
in diameter than the working bubble 200.
FIG. 6b shows the working bubble 206 and target bubble 208 at their
maximum expanded diameters, just before they collapse.
FIG. 6c shows both bubbles 240 and 242 beginning to collapse.
FIG. 6d shows the initial formation of the re-entrant micro-jet 248
by bubble 244. Since target bubble 246 is further than six target
bubble diameters from bubble 244, it does not "sense" (fluid
mechanically) the presence of working bubble 244 and therefore will
not launch a jet in its direction. Since both the target bubble 246
and the working bubble 244 are within six working bubble diameters
of the surface of work piece 204, the re-entrant micro-jet from
collapsing working bubble 244 is launched in a direction between a
path normal to the work surface and a path through target bubble
246. In the absence of any target bubble, the re-entrant micro-jet
would be launched in a direction normal to the surface, but the
location of impact would be unpredictable.
FIG. 6e shows the net effect of the re-entrant micro-jet 252
launched near the target bubble 254 (but not through it) to the work
piece 204.
FIG. 7 is a schematic diagram of a working bubble 300 and a target
bubble 304 directing convergent re-entrant micro-jets 302, 308 to a
work surface 314 in accordance with one embodiment of the present
invention. In this case, distance 312 is less than six working
bubble diameters and distance 310 is less than six target bubble
diameters. For target bubbles 304 significantly smaller than working
bubbles 300, the re-entrant micro-jets emanating from the target
bubble will be directed toward the surface 314. It is possible to
adjust the spatial position of working bubble 300 in order to direct
its re-entrant micro-jet 302 to a position convergent with jet 308
from the target bubble 304, as was shown in FIGS. 6a-e. This
technique may be useful for amplifying the impact of the jets upon
the work surface, or providing-jets from two different angles to the
same location.
FIG. 8 is a schematic diagram 350 of three re-entrant micro-jets
being directed at a movable work piece in accordance with one
embodiment of the present invention. Three re-entrant micro-jets
370, 372, and 374 are directed at a movable section 354 of work
piece 352. Jet 370 is formed by the collapse of cavitation bubble
356 through target bubble 362. Jet 372 is formed by the collapse of
cavitation bubble 358 through target bubble 364. Jet 374 is formed
by the collapse of cavitation bubble 360 through target bubble 368.
Cavitation bubbles 356, 358, and 360 may be formed simultaneously or
in a sequence, depending on the sequence of forces required to
locate movable member 354 to its desired location 376. This process
may be applied, for example, by a surgeon who wants to precisely
locate a small section of tissue that has become detached from its
desired position. A folded retina is one such possibility. By
adjusting the distance of bubbles 356, 358, and 360 to work piece
354, and their maximum diameters, the forces imparted to tissue may
be carefully adjusted to a level sufficient to do the job without
imparting collateral damage to the structures being moved.
FIG. 9 is a cross sectional view 400 of a cylindrical pore 420 in
which the re-entrant micro-jet 408 from a working cavitation bubble
404 directed through a target bubble 406 are cutting a cavity 410 in
the side wall of the pore 402 in accordance with one embodiment of
the present invention. Cavitation bubble 404 and target bubble 406
are nucleated within cylindrical pore 402. Re-entrant micro-jet 408
directed toward the wall of pore 402 cuts a channel 410 while
impinging on surface 412. The depth of channel 410 will depend on
the number of times bubbles 404 and 406 are generated. For pore
diameters of 5 to 10 microns, re-entrant micro-jets on the order of
10 to 20 nanometers can be created, creating channels in the side
walls in the 20 to 30 nanometer range. In silicon substrates, this
could allow fabrication of trench capacitor structures of extremely
small dimension, utilizing a volume of the substrate not accessible
previously. The fabrication technology may enable true three
dimensional device fabrication strategies to produce nanometer
device geometry's without the use of lithography.
FIG. 10 is a top view looking into the cylindrical pore 402 of FIG.
9 in accordance with one embodiment of the present invention.
FIG. 11 is a cross sectional view of a cylindrical pore where the
re-entrant micro-jets from a working bubble directed through a
target bubble are cutting multiple cavities in accordance with one
embodiment of the present invention. Cavitation bubble 404 is shown
cutting multiple cavities 410a and 410b. This can be accomplished by
placing target bubble 406 in the appropriate direction.
FIG. 12 is a top view looking into the pore of FIG. 11 showing
multiple cavities formed at 90 degree angles in accordance with one
embodiment of the present invention. By positioning the target
bubble 406 on dotted circular path 414 at positions 418, 416, and
420 cavities 410b, 410c, and 410d can be fabricated, respectively.
Although four cavities are shown in this figure, many others at any
desired spacing can be fabricated as will be appreciated by those
skilled in the art.
FIG. 13 is a top view looking into the cylindrical pore of FIG. 11
wherein a continuous horizontal slot has been fabricated in
accordance with one embodiment of the present invention. When a
series of cavitation target bubbles 406 are moved in a continues
manner along path 414, a resulting horizontal slot at depth 412' can
be produced. By altering the depth that working bubble 404 and
target bubble 406 are situated in the pore 402, multiple horizontal
slots at varying depths can be fabricated as well. Due to the
intense power of the re-entrant micro-jets, the hardest materials
can be eroded with this technique, including crystalline silicon.
Multiple slots produced in a horizontal fashion could provide a
basis for very high surface area capacitors for advanced memory
devices.
FIG. 14 is a cross sectional view of a cylindrical pore 402 in where
the re-entrant micro-jets 408 from a working bubble 404 directed
through a target bubble 406 are cutting a cavity at an angle not
normal to the surface of the pore in accordance with one embodiment
of the present invention. In this case target bubble 406 is placed
in a horizontal plane above or below cavitation bubble 404. If the
position of bubbles 404 and 406are held constant, the re-entrant
micro-jet 408 will cut a cavity 422 at an angle to the vertical wall
of pore 402. By placing target bubble 406 at fixed depth intervals,
cavities at various angles of depth 426 can be produced. By
adjusting the depth of target bubble 406 in a continues manner, a
larger cutout following the outline 424 may be obtained. By applying
the techniques illustrated in the previous FIGS. 9-14, practically
any profile or shape can be fabricated in the walls of a pore.
FIG. 15 is a schematic view of a cavitation based process for
injecting solution components into liposomes in accordance with one
embodiment of the present invention. Liposomes are microscopic,
fluid-filled pouches whose walls are made of layers of phospholipids
identical to the phospholipids that make up cell membranes. The
fluid inside the pouch may contain soluble drugs designed to be
delivered to cells when the liposomes merge with the cell walls of a
targeted cell. One way to inject the drug into the interior of a
liposome is shown in via the apparatus 450 in this figure. A
container 452 contains a fluid solution 454, a liposome
manufacturing module 456 (which can also reside outside the walls of
container 452), and a nozzle 458 for delivering liposomes 460 to the
fluid 454. The liposomes may be manufactured with no drugs in their
interiors, some amount of the desired drug, or a mixture of
completely different drugs. The drugs to be injected are present in
the solution 454. In one example, a cavitation bubble 464 is
nucleated within five bubble diameters of a liposome 460b. The
liposome acts like a target bubble, attracting the re-entrant
micro-jet 472. Adjustment of the control volume and initial energy
dose will determine the size of the cavitation bubble, and therefore
the size of micro-jet 472. The collapsing cavitation bubble entrains
components of the solution 454, including the drugs to be injected,
and the micro-jet 472 delivers these components through the wall of
the liposome 460b. In a second example, a target bubble 468 is
nucleated in the proximity to a working bubble 462, in such a manner
as to direct a re-entrant micro-jet 470 into the interior of
liposome 460a. This method allows the working bubble 462 to be a
further distance from liposome 460a, allowing additional flexibility
in reducing dosage levels injected into the liposome, as well as
reducing the potentially damaging impact of a jet launched in close
proximity.
US7517430
Method and apparatus for the
controlled formation of cavitation bubbles
Inventor: LECLAIR MARK L [US]
EC: A61B18/26
IPC: A61B18/26 C23C16/00 H01B13/00
2009-04-1
The present invention discloses a method and apparatus for the
directed formation of a re-entrant micro-jet formed upon the
collapse of a cavitation bubble formed proximate to a work surface
placed in a fluid. A mask containing an orifice, placed between the
work surface and the cavitation bubble, is utilized to direct the
re-entrant micro-jet to the work surface. The cavitation bubble may
be formed in the desired location by focusing an energy flow
proximate to the mask. The energy flow may be obtained by radiation
from laser, x-ray, or electrical discharge sources.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to the formation and control of
individual micron size and submicron size cavitation bubbles for use
in nanofabrication operations. More particularly, embodiments of the
invention teach methods and apparatus for control of a re-entrant
micro-jet formed upon collapse of an individual or array of
cavitation bubbles and directing the impact of the micro-jet toward
a work surface with a high degree of precision.
2. Description of the Related Art
In general, the production of cavitation has been a phenomena many
have tried to avoid. Cavitation in a liquid is the formation,
growth, and collapse of gaseous and vapor bubbles due to the
reduction of pressure below the vapor pressure of the liquid at the
working temperature. Pump impellers, boat props, and similar
applications experience cavitation which can produce rapid damage
and erosion of surfaces. It has been well known for many years that
ultrasonic cleaning devices, which function by the creation of
cavitation bubbles, can produce significant surface damage to even
the hardest of materials. Studies by a number of authors have
revealed that one significant element in producing the damage caused
by cavitation occurs when a cavitation bubble collapses in the
vicinity of a surface, launching what is called a re-entrant
micro-jet toward the surface. This liquid jet can produce velocities
as high as 1500 m/s, and is capable of damaging the hardest
materials known.
Recently, a number of applications have been developed utilizing the
formation of cavitation bubbles through the use of laser light or
electrical discharge. Esch et al. (U.S. Pat. No. 6,139,543) and
Herbert et al. (U.S. Pat. No. 6,210,400) disclose the use of laser
light introduced into a catheter device for the purpose of creating
cavitation bubbles, whose expansion and collapse are utilized to
pump fluids in and out of the catheter. Hammer et al. (U.S. Pat. No.
5,738,676) discloses a laser surgical probe with a special lens
designed to produce the cavitation bubbles further from the end of
the fiber optics, to reduce the damage formed (presumably by the
re-entrant micro-jets launching into the lens on the end of the
cable). Such damage was also reported by Rol et al. in "Q Switched
Pulses and Optical Breakdown Generation Through Optical Fibers",
Laser and Light in Opthalmology, Vol. 3, No. 3, 1990. Palanker (U.S.
Pat. No. 6,135,998) describes a method for performing electrosurgery
using sub-microsecond, high power electrical pulses are applied to
an electrosurgical probe interface. The tool described by Palanker
provides a cutting force by both the plasma generated by the
electrical arc and shock waves produced by collapsing cavitation
bubbles.
In each of the prior art references cited above, there has been no
attempt to control the direction and impact of the powerful
micro-jets formed upon the collapse of the cavitation bubbles
created when highly focused energy is introduced into a liquid.
Without such control, concern of collateral damage cannot be
avoided, especially when such tools are used in the human body in a
medical application.
Recently as well, there has been a significant interest generated in
the field of nanotechnology, for methods needed to fabricate micron
and submicron devices and nanomachines. There are very few
fabrication tools available that can cut, drill, peen, deform, or
otherwise modify features of a surface on a submicron to nanometer
scale. Much of the technology developed by the semiconductor
industry requires the fabrication of structures utilizing
photolithographic processing. This technology is not as flexible as
may be required, and will have certain difficulties when applied to
biological nanotechnology systems. Advancing the state of the art
required by nanotechnology applications will require fabrication
technologies operating at least 1 to 2 orders of magnitude below
that capable in the semiconductor process arena.
The prior state of the art therefore has yet to provide a
fabrication technology capable of operating in the nanometer region
by harnessing the powerful phenomena of the re-entrant micro-jet
formed during the collapse of a precisely located cavitation bubble.
SUMMARY OF THE INVENTION
An apparatus for the controlled formation of cavitation bubbles in
accordance with the present invention includes a mask immersed in a
liquid proximate to a work surface, wherein the mask has a first
surface opposing and separate from the work surface, a second
surface opposing the first surface, and at least one aperture
extending from the first surface to the second surface. The
apparatus further includes an energy source capable of generating an
energy flow in the liquid sufficient to create at least one
cavitation bubble, the cavitation bubble being located opposite the
second surface proximate to the aperture, wherein a collapse of the
cavitation bubble creates a re-entrant micro-jet directed through
the aperture at the work surface.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a schematic view of a
cavitation initiation volume in accordance with one embodiment of
the present invention.
FIG. 1B is a schematic view of a
fully expanded cavitation bubble in accordance with one embodiment
of the present invention.
FIG. 1C is a schematic view of a
collapsing cavitation bubble in accordance with one embodiment of
the present invention.
FIG. 1D is a schematic view of the
initial formation of a re-entrant micro-jet induced by the
collapsing cavitation bubble in accordance with one embodiment of
the present invention.
FIG. 1E is a schematic view of a
re-entrant micro-jet directed through an aperture to a work
surface in accordance with one embodiment of the present
invention.
FIG. 2 is a schematic view of a
lens focused laser apparatus for producing cavitation induced
re-entrant micro-jets in accordance with another embodiment of the
present invention.
FIG. 3 is a schematic view of a
parabolic mirror focused laser apparatus for producing cavitation
induced re-entrant micro-jets in accordance with another
embodiment of the present invention.
FIG. 4 is a schematic view of a
lens focused x-ray source apparatus for producing cavitation
induced re-entrant micro-jets in accordance with another
embodiment of the present invention.
FIG. 5 is a schematic view of a
parabolic mirror focused x-ray source apparatus for producing
cavitation induced re-entrant micro-jets in accordance with
another embodiment of the present invention.
FIG. 6 is a schematic view of
spatial filter added to a lens focused laser apparatus for
producing cavitation induced re-entrant micro-jets in accordance
with another embodiment of the present invention.
FIG. 7 is a schematic view of an
electric discharge apparatus for producing cavitation induced
re-entrant micro-jets in accordance with another embodiment of the
present invention.
FIG. 8 is an apparatus for the
production of an array of cavitation induced re-entrant micro-jets
in accordance with another embodiment of the present invention.
FIG. 9 is a schematic view of an
apparatus for the welding of small particles in a cavitation
induced re-entrant micro-jet in accordance with another embodiment
of the present invention.
FIG. 10 is a table of
parameters for the application of various pulsed Gaussian TEMOO
lasers for a number of embodiments in accordance with the present
invention.
FIG. 11 is a table of parameters
for the application of an electric discharge for one embodiment in
accordance with the present invention.
DETAILED DESCRIPTION OF THE
PREFERRED EMBODIMENT(S)
The sequence illustrated in FIGS. 1A-E illustrate the formation of a
re-entrant micro-jet from the formation and collapse of a cavitation
bubble in accordance with the present invention.
FIG. 1A is a schematic view of a cavitation initiation volume in
accordance with one embodiment of the present invention. The energy
from a cavitation initiation device (not shown) is focused into a
volume 2 aligned over aperture 4, at a nominal distance 3 from
aperture mask 6 placed in proximity to a work piece surface 8. The
intense energy focused into the small focus volume 2 is absorbed by
the fluid 1, causing rapid boiling and expansion of vaporized
gasses. Arrows 10 represent the rapid movement of the gas liquid
boundary of the cavitation bubble formed in volume 2. Energy sources
may include, but are not limited to: lasers, x-ray sources,
ultrasound, electrical discharge, and positrons.
FIG. 1B is a schematic view of a fully expanded cavitation bubble in
accordance with one embodiment of the present invention. Cavitation
bubble 12, formed from the rapid expansion of vaporized fluid in
volume 2 and the momentum of liquid moving away from the center of
the focus volume 2, has reached its maximum diameter 5. Typically,
the maximum diameter 5 of the fully expanded cavitation bubble 12 is
approximately 10 to 50 times the diameter of the focus volume 2
shown in the previous FIG. 1A. Gas pressure inside fully expanded
cavitation bubble 12 may be as low as the vapor pressure of fluid 1
at it's bulk temperature. The pressure of the surrounding fluid 1,
typically at 1 atmosphere absolute or higher, creates a pressure
differential on the outer surface of the bubble 12, driving its
subsequent collapse. For fluids 1 such as water at 1 atmosphere and
25[deg.] C., the pressure differential can exceed 700 torr.
FIG. 1C is a schematic view of a collapsing cavitation bubble in
accordance with one embodiment of the present invention. Cavitation
bubble 14 has begun a rapid collapse illustrated by rapid inner
movement of its outer surface and arrows 16.
FIG. 1D is a schematic view of the initial formation of a re-entrant
micro-jet 20 induced by the collapsing cavitation bubble 16 in
accordance with one embodiment of the present invention. Re-entrant
micro-jet 20 is launched through aperture 4 toward work surface 8.
Aperture mask 6 serves to block subsequent shock waves produced by
collapsing cavitation bubble 16 from work surface 8, allowing only
the high velocity, focused re-entrant micro-jet to impact the
surface.
FIG. 1E is a schematic view of a re-entrant micro-jet directed
through an aperture to a work surface in accordance with one
embodiment of the present invention. The fully formed re-entrant
micro-jet 24 impacts the work surface 8 through aperture 4. The
re-entrant micro-jet 24 may impact the work surface with velocities
as high as 1500 meters/second, and is capable of removing material
from the hardest surfaces known, such as diamond. These jets may be
used to cut, machine, drill through, erode or deform features on the
work surface 8. The diameter of the jets are determined by the size
of the cavitation bubble 12 formed, which in turn is determined by
the dimensions of the focus volume 2 and the level of energy
introduced into said focus volume. As will be illustrated in
subsequent figures, the re-entrant micro-jet 24 diameters may vary
from about 1 micron to about 1 nanometer for focused laser and x-ray
energy sources. Electric discharge sources may produce re-entrant
micro-jet diameters on the order of 10 to 15 microns. The velocity
of the re-entrant micro-jet through the aperture is primarily
determined by the distance 3 of the focus volume 2 to the aperture
mask 6, and can vary from [1/2] the expanded bubble diameter 5 to
about 6 times the expanded bubble diameter 5, with the optimum
distance being approximately 3 expanded bubble diameters 5. The
impact force of the re-entrant micro-jet 24 on work surface 8 may be
adjusted by altering the distance 7 between the aperture mask 6 and
the work surface 8. At a given jet velocity (or fixed distance
between the focus volume 2 and aperture mask 6), the impact force
will vary inversely with the distance 7, in a range from
approximately zero to 6 expanded bubble diameters 12, but preferably
in a range from zero to 4 bubble diameters 12. The diameter of the
aperture 4 can be in a range from about 1% to 30% of the expanded
bubble diameter. The re-entrant micro-jet diameter is on the order
of about 0.2% of the expanded bubble diameter 12.
The aperture mask 6 and aperture 4 play an essential role in
directing and controlling the action of the re-entrant micro-jet 24.
Without the aperture mask, the collapse of the cavitation bubble
(12, 14, 16) would still launch a re-entrant micro-jet toward the
surface 8, but the location of impact and the force imparted would
be unpredictable, especially on a nanometer scale. In addition, the
aperture mask tends to keep shock waves created in the expansion and
contraction stages from damaging the surface 8. Accurate placement
of the aperture and the focus volume allow nanometer scale precision
cutting, punching, peening, drilling, or deforming operations on
sub-micron scale features of the work surface. Many prior art
applications are capable of accurate placement of the initial focus
volume, but do little or nothing to control the shock waves and
re-entrant micro-jet formed upon collapse of the cavitation bubble.
FIG. 2 is a schematic view of a lens focused laser apparatus for
producing cavitation induced re-entrant micro-jets in accordance
with another embodiment of the present invention. Sealed tank 30
contains liquid filled to a level 32. Various liquids can be used,
but high purity water (>100 k ohms resistivity) is preferred. The
beam from laser 34 is directed to lenses 40a and 40b to collimate
the beam, which is then focused by lens 48 at a focal distance 50.
Beam focus positioner 36 determines the location of the focus volume
2 relative to the aperture mask 6, at a distance 52. Work surface 8
is moved by precision XYZ stage 60, to adjust the distance from
aperture mask 6 to the work surface, as well as locate the specific
area on the work surface to be impacted by the jet 24. Recall from
previous FIGS. 1A-E, that the position of the focus volume
determines the location of the subsequent cavitation bubble 44 and
re-entrant micro-jet 24. Fluid inlet 56 and outlet 58 are utilized
to provide a constant flushing of the fluid in the tank 30, in part
to remove any debris produced by the machining occurring on the work
surface 8. This debris may negatively impact the absorption of
subsequent laser light pulses in the focus volume, as well as
potentially contaminate the surface with entrained particle matter
introduced into the re-entrant micro-jet. For similar reasons, it
may be desirable (although not essential) to filter the incoming
fluid stream 62 to remove any particulate contamination. Tank 30 is
equipped with a pressure transducer 38 to monitor and control the
back pressure. For a sealed tank as shown, this may be done simply
by raising the inlet pressure of incoming fluid stream 62 with
respect to the outlet pressure of outlet stream 64, by choking the
outlet flow until the tank ambient pressure is as desired, the
re-equilibrating the flows once again.
FIG. 3 is a schematic view of a parabolic mirror focused laser
apparatus for producing cavitation induced re-entrant micro-jets in
accordance with another embodiment of the present invention. As was
shown in FIG. 2, laser 34 directs a beam into collimator lenses 40a
and 40b. The collimated beam is directed onto a parabolic mirror 66,
which also contains the aperture 4. Parabolic mirror 66 focuses the
collimated laser beam to a focus volume at a distance 52 from the
aperture. In this embodiment, distance 52 is fixed by the curvature
parameters of the parabolic mirror 66, and therefore the velocity of
the re-entrant micro-jet 24 is also fixed. An XYZ stage 60
determines the distance 54 from the aperture to the work surface, as
well as the XY coordinates of the area to be worked on. All other
features are as described in FIG. 2.
FIG. 4 is a schematic view of a lens focused x-ray source apparatus
for producing cavitation induced re-entrant micro-jets in accordance
with another embodiment of the present invention. X-ray source 70
directs a beam into x-ray lens 72, which focuses and concentrates
the x-ray beam into a focus volume at a distance 52 from an aperture
mask 6. Aperture positioner 76 adjusts distance 52 to alter
re-entrant micro-jet velocity through the aperture 4. Dimension 54,
or the distance of the aperture mask to the work surface 8 is
adjusted by XYZ stage as has been previously described. All other
features are as described in FIG. 2.
FIG. 5 is a schematic view of a parabolic mirror focused x-ray
source apparatus for producing cavitation induced re-entrant
micro-jets in accordance with another embodiment of the present
invention. X-ray source 70 directs a beam onto parabolic x-ray
mirror 80 containing an aperture 4. The x-ray beam is focused into a
focus volume at a distance 52 from the aperture 4. The dimension 54
between the aperture mask 6 and work surface 8 is adjusted by the
XYZ stage 60. In this embodiment, distance 52 is fixed by the
curvature parameters of the parabolic mirror 80, and therefore the
velocity of the re-entrant micro-jet 24 is also fixed.
FIG. 6 is a schematic view of spatial filter added to a lens focused
laser apparatus for producing cavitation induced re-entrant
micro-jets in accordance with another embodiment of the present
invention. Spatial filter 86 can be optionally added to the
previously described embodiments to further clean up the laser beam
or x-ray beam to allow smaller focus volumes. The spatial filter 86
comprises a entrance lens 82, a pinhole 85, and an exit lens 83.
Exit lens 83 and lens 40 makes up part of the collimator lens pair
as shown in previous figures.
FIG. 7 is a schematic view of an electric discharge apparatus for
producing cavitation induced re-entrant micro-jets in accordance
with another embodiment of the present invention. A positive
electrode 88 and negative electrode 90 are immersed in fluid 32 and
positioned to generate an arc at a position a distance 52 above
aperture mask 6. Actuator 76 adjusts dimension 52 to position the
focus volume a known distance from the aperture mask 6. The arc is
created by rapid discharge of capacitor 96 through switch 94. Full
circuit details are not shown in FIG. 7, but are well known to those
skilled in the art. Capacitor 96 is a low inductance, high voltage
device as is used in pulse lasers and flash tubes. The rapid
discharge and subsequent transient arc create a cavitation bubble 44
as illustrated in FIGS. 1A-E.
FIG. 8 is an apparatus for the production of an array of cavitation
induced re-entrant micro-jets in accordance with another embodiment
of the present invention. Work surface 8 is placed parallel to an
aperture mask 6' containing a plurality of apertures. Cavitation
bubbles 44a, 44b (only two are shown for clarity) are formed
directly over each aperture in the array by any number of
techniques, as previously discussed, such that the re-entrant
micro-jets 24a, 24b formed following the collapse of the cavitation
bubbles are directed through the apertures 4a, 4b normal to the
surface 6' and impact work surface 8. The cavitation bubbles may be
formed simultaneously or sequentially, or in some other pattern
(such as every other aperture, every two apertures, etc.). If the
cavitation bubbles 44 are formed over each aperture simultaneously,
then the aperture spacing dimensions 100 and 102 must be determined
such that they are at least 6 expanded bubble diameters 12 long.
These dimensions may be shortened, for example, to 3 expanded bubble
diameters 12 if the cavitation bubbles are formed over every other
aperture, as long as there remains at least 6 fully expanded bubble
diameters between any two cavitation bubbles in the array being
formed simultaneously. For cavitation bubble spacing closer than the
6 expanded bubble diameters, there is some probability (increasing
with decreasing bubble spacing) that the re-entrant micro-jets
produced on collapse of the adjacent cavitation bubbles will be
directed toward each other, as opposed to being directed through the
apertures. This is undesirable. Alternatively, aperture mask 6' may
be moved relative to work surface 8 to place the impact location of
the various re-entrant micro-jets in any desired location on the
work surface.
The array of cavitation bubbles may be produced by a number of
techniques in accordance with the present invention. For example, an
array of lasers as illustrated in FIGS. 2, 3, and 6 may be employed.
Or a single laser having a fiber optic array employing multiple
collimators located over each aperture 4a, 4b may also be used.
Additionally, a single laser and collimator may be scanned over the
aperture array such that each "firing" of the pulse laser produces a
focus volume of light energy over the appropriate aperture position.
The same process may also be utilized with the x-ray source.
Additionally, the aperture location may be moved by XYZ stage 60
while holding the aperture mask 6' fixed over the work surface 8,
utilizing a single laser or x-ray source. For the case of the
electrical discharge, a multiple electrode array may be used, or the
array may be positioned under a single electrode pair via the XYZ
stage. An array of cavitation bubbles may also be produced by
ultrasound techniques. It is well known to those skilled in the art,
that many ultrasound transducers produce a three dimensional array
of cavitation bubbles in a tank of fluid corresponding to a standing
wave pattern of sound waves in the fluid. By creating and
positioning such a standing wave pattern over the aperture mask 6',
cavitation bubbles formed due to the ultrasound will collapse,
directing the previously described re-entrant micro-jets through the
apertures to the work surface. Not every cavitation bubble produced
in the standing wave field need be located over an aperture. Those
that are not will simply launch their respective jets against the
mask 6'. It is important that no cavitation bubbles are formed
between the mask 6' and the work surface 8. These bubble may damage
the surface since the impact of their jets would uncontrolled and
potentially misdirected. The properties of the ultrasound generated
cavitation bubbles should conform to previously determined
requirements as discussed in FIG. 1E.
FIG. 9 is a schematic view of an apparatus for the welding of small
particles in a cavitation induced re-entrant micro-jet in accordance
with another embodiment of the present invention. Introduction of
particulate matter 112 into the re-entrant micro-jet may result in
the welding of the particles to each other and/or to the work
surface 8. Small particles 108 stored in a container 106 are
released into solution via valve 110 in the vicinity of the focus
volume 2, where a cavitation bubble will be nucleated, as previously
described. Particles 108 may be stored in a dry form, but preferably
are mixed and suspended in a compatible fluid. Once in solution,
these particles 112 will accumulate at the gas liquid interface of
the cavitation bubble, and may be entrained into the re-entrant
micro-jet as the cavitation bubble collapses. The very high impact
forces of the micro-jet hitting the work surface causes the welding
of these particles to each other and the work surface 8. This
process may be used to build microstructures of various types of
materials on the work surface. One application of importance would
include the construction of photo resist masks for micro and nano
circuit fabrication. Since photo lithography is not required for
this process, the lower limits imposed by that process can be easily
exceeded. The fabrication of submicron and nano scale particles is
well known to those skilled in the art, as is the technology for
suspending such particles in a fluid. By translating work surface 8
under aperture 4 while sequentially forming a series of cavitation
bubbles 2, many types of submicron layer structures can be built.
The materials making up these structures can also vary considerably,
and may include polymers, metals, and inorganic ceramic materials.
Some of these materials may have superior etch, resist properties
that conventional organic films used today do not posses.
Additionally, cavitation welded films may not need curing and baking
as is required for conventional polymer photo resists.
FIG. 10 is a table of parameters for the application of various
pulsed Gaussian TEM00 lasers for a number of embodiments in
accordance with the present invention. In this table, the
relationships between various laser parameters (such as laser type,
spectrum of the emitted radiation and wavelength, collimated beam
radius, focus diameter, and cylindrical focus volume) and the
resulting cavitation bubble parameters (such as the cavitation
bubble diameter and the re-entrant microjet diameter) are shown. All
parameters are normalized to a collimated laser beam diameter of 10
mm. This dimension was chosen for convenience, and does not imply
that collimated laser beams of larger or smaller dimensions are not
applicable. In one example, a CO2 laser beam of 10 mm producing an
infra-red wavelength of 10.6 microns is focused to a 10.8 micron
diameter in the fluid. This focused beam results in a control volume
2.8*10<-9 >cm<3>, generating a cavitation bubble 520
microns in size at maximum diameter. After collapse, this cavitation
bubble produces a re-entrant micro-jet of 1200 nanometers in
diameter. In a second example, an excimer laser beam of 10 mm
producing an ultra-violet wavelength of 0.13 microns is focused to a
0.13 micron diameter in the fluid. This focused beam results in a
control volume 5.1*10<-15 >cm<3>, generating a
cavitation bubble 6.4 microns in size at maximum diameter. After
collapse, this cavitation bubble produces a re-entrant micro-jet of
14 nanometers in diameter. In yet a third example, an x-ray beam of
10 mm producing an x-ray wavelength of 0.01 microns is focused to a
0.01 micron diameter in the fluid. This focused beam results in a
control volume 2.3*10<-18 >cm<3>, generating a
cavitation bubble 0.49 microns in size at maximum diameter. After
collapse, this cavitation bubble produces a re-entrant micro-jet of
1.1 nanometer in diameter. As can been seen from the aforementioned
examples, re-entrant micro-jets ranging over 3 orders of magnitude
in diameter can be produced by changing the type of laser energy
used to create the cavitation bubble, and can produce the smallest
jets on the order of 1 nanometer in diameter.
FIG. 11 is a table of parameters for the application of an electric
discharge for one embodiment in accordance with the present
invention. For convenience, the data presented is based on the
discharge of a 1 micro Farad capacitor. Capacitor values greater or
smaller than this value are also equally applicable. In one example,
the 1 micro Farad capacitor is charged to 5000 volts and discharged
into the fluid generating a cavitation bubble 6 mm in diameter,
creating a re-entrant micro-jet of approximately 14 microns in
diameter. In a second example, the 1 micro Farad capacitor is
charged to 2000 volts and discharged into the fluid generating a
cavitation bubble 3 mm in diameter, creating a re-entrant micro-jet
of approximately 8 microns in diameter.
US5522553
Method and apparatus for producing
liquid suspensions of finely divided matter
Inventor: LECLAIR MARK L [US]
HIGGINS JOHN A [US]
Applicant: KADY INTERNATIONAL [US]
EC: B02C18/00W2 B02C18/06B
IPC: B02C18/06 (IPC1-7):B02C18/40
1996-06-04
