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BACKGROUND OF THE INVENTION
The present invention relates to a micromechanical structure for purposes
of biotechnology, gene technology, cell research, pharmacology for healing
and research on sicknesses which have been uncurable to date, also for
agriculture research, to open up new sources of nutrition and energy and
to restore the environment, for purposes of medicine, for instance, blood
analysis but also of tissue and cells, for instance, antibody, antigen
immobilization for preparing monoclonal antibodies, for preparing
antibiotics, insulin and also for medications, sera, bacterial and other
substance investigations and comparison tests. There is always the problem
of safely controlled handling of the respective substance during and after
an investigation, reaction or the like, especially if the substances can
constitute a danger for the environment.
To meet the purposes mentioned above, particularly for fighting sickness
and hunger in the world, it is necessary to be able to safely handle, in
investigations, reactions, tests, comparison investigation and
investigation series with, in particular, dangerous substances, also if
the amounts of substance are ever so small.
SUMMARY OF THE INVENTION
It is an object of the present invention to facilitate or ensure clean,
safe storage and handling of substances which are dangerous or could
become so, be it prior to, during or after an investigation, reaction,
test or the like
The above and other objects of the invention are achieved by a
micromechanical structure with cavities, for investigating sample
substances for possible changes of physical and/or chemical properties
and/or bio-chemical properties, evaluation and documentation in a targeted
manner for the purposes of biotechnology, gene technology, cell and
immunity research and other medical, agricultural and environment
research, wherein the structure comprises at least one of the group of
semiconductive material (of the group III to V of the elements of the
periodic system), glass, ceramic, diamond or carbon and is made by a
masking technique, particularly by chemical etching techniques.
This microstructure has many advantages. It can be produced
cost-effectively in large quantities. It is suitable for the safe storage
for a multiplicity of substances such as samples for tests, for
treatments, for investigation, for comparisons, for reactions, etc. The
arrangement of suitable cavities relative to each other in the structure
in the manner of a matrix or an array permits simple process control and
the carrying-out of desired reactions, of desired small amounts of
substance as well as their targeted treatment and examination. The
structure with the cavities consists of inert material, i.e., it does not
change in the investigations and treatments; the cavities can be closed
off reliably and are not attacked by most toxic substances.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described in greater detail in the following detailed
description with reference to the drawings, in which:
FIG. 1 shows a structure with a single cavity and a definite surface
orientation of the crystalline material;
FIG. 2 shows a modification of FIG. 1;
FIG. 3 shows a structure of crystalline material;
FIG. 4 shows a structure as a modification of FIG. 3;
FIG. 5 shows a structure in a design modification of FIG. 1;
FIG. 6 shows a modification of FIG. 2 or 4, where a structured portion in
the center between portions different therefrom is arranged (sandwich
construction);
FIG. 7 shows a modification of FIG. 6 with devices additionally arranged in
the bottom plate and cover plate;
FIG. 8 shows a further modification of FIG. 6 or 7 with additional layers
or plates;
FIG. 9 shows a design with a measuring or pickup device;
FIG. 10 shows a structure with a measuring and pickup device as well,
optionally with memory;
FIG. 11 shows a device with a biosensor, especially a field-effect
transistor;
FIG. 12 shows a modification of the embodiment according to FIG. 1;
FIG. 13 shows a device for ascertaining given substances in fluids;
FIG. 14 shows a device for automatic examination with documentation of the
examination results;
FIG. 15 shows a heat exchanger, especially a plate cooler;
FIG. 16 is a top view of FIG. 15;
FIG. 17 is modification of FIG. 15; and
FIG. 18 is top view of FIG. 17.
DETAILED DESCRIPTION
As shown in FIG. 1, a structure 1 consists of walls with one and preferably
several cavities therein to contain small amounts of substance, and the
block is closed off with a cover 3. The block 1 and the cover 3 are made
of crystalline material such as semiconductor material. Likewise, for
closing off the container according to the invention, a counterpiece,
cover 3, is generated with a second mask which has humps 4 corresponding
to the depressions 2, since the masks are geometrically identical. The
mask technique permits high precision in production; it is known per se
from semiconductor technology.
With the mentioned technique it is an advantage to apply an anisotropic
etching method depending on the crystal orientation because thereby,
utilizing the self-limiting action of (111) crystal planes, depressions
with high geometric precision and very narrow tolerances can be realized.
The container in FIG. 1 can be produced on (100) silicon, where the
laterally limiting (111) planes make an angle of 54.7.degree. to the wafer
surface The invention is not limited to the abovementioned etching
technique. Other known kinds of making depressions in semiconductor or
similar crystalline materials can be applied such as laser beam drilling.
The cover 3 can be provided with a hump 4 which has the same 54.7.degree.
inclination to the crystal surface as the container block 1 in the area 2
and therefore seals perfectly tight. This is true also if the cover has a
multiplicity of humps and the block 1 a multiplicity of depressions 2. If
the fitting accuracy of the humps and depressions at the cover 3 and the
block 1, made by the etching method are not sufficient for specific
applications of particularly dangerous substances, a circular seal can be
used in addition. FIG. 5 shows an embodiment which in turn corresponds to
the 54.7.degree. inclination of the hump form of the cover and form a
closure with a further inclination. In addition, adhesives or other
joining techniques can be used for increasing the tightness. In
particular, a laser beam can also be used with a seam welding process at
the circular rim of the cover. A multiplicity of cavities 2 is not limited
as far as size, design and distribution in the block of the container.
The cavities 2 (and the humps 4) may, in particular, be square,
rectangular, circular, oval or diamond-shaped. They can be tapered or
expanded toward the body, see FIG. 1 and FIG. 2, or keep the same cross
section if drilled, for instance, with a laser beam (FIG. 4). They can
have also other cross sections or shapes (openings, canals).
An additional layer or plate 5 serves as a carrier or intermediate carrier
(removable) advantageously of the same material, for instance, silicon or
the like, as the body of the container, likewise providing a hermetically
tight closure.
The structure 1 worked out from a block material advantageously (for mass
production) forms a plane plate with through cavities 2 such as openings,
canals or the like of desired shape etched by wet chemistry,
advantageously from silicon, while the cover 3 and the bottom 5 consist of
material which can be joined preferably well to this material of the
structure 1, especially of material which can be sealed off hermetically
tight such as glass, silica, glass ceramic or synthetic silicon or silicon
metal compound material.
In FIG. 6, the bottom 5 is further covered, as shown in FIG. 6, with a
layer 7 which may be, for instance, a filter layer, a sedimentation layer,
an inert or catalytic or otherwise reacting layer of a material or only
absorbing material. A fiber fleece or a woven fleece with large pores and
a large open surface, a fiber layout, foam material or a similar permeable
structure can be used, depending on the application (collecting, storing,
reacting). This may involve a neutral carrier material or an active
carrier material which is used for the layer 7 and underneath valves for
further devices (see FIG. 8) can be used for the layer 7. The block 1 with
the cavities 2 contains them advantageously according to a raster measure
in an X-Y distribution over the surface of the preferred silicon crystal
as an array or in matrix form (see FIG. 3) so that they can be filled,
gassed, injected, thinned, depleted, suctioned off or the like, for
instance, by means of automatic devices, mixed or brought to reaction. The
supply or discharge organs are then program-controlled line by line until
the entire surface is scanned, as known per se, in automatic analyzers or
automatic handling devices or robots for medical or other research
purposes.
The material of block 1 must in any case be inert against the substance
which is to be examined, treated, thinned or mixed. Or is to be the
subject of a reaction or is to be tested for a particular result or the
lack thereof.
Depending on the purpose for which the invention is applied, the cavities
for examining or storing (storage containers) can be made larger
especially if the cavities 2 in block 1 are only part of sampling or
examination or reaction chambers-see FIG. 7. The matrix or array
arrangement in the X-Y direction is retained as described above and also
the essentially sandwich-like construction according to FIG. 6. In
addition, there is correlated in the cover plate 3 and the bottom plate 5,
with the respective cavity, a further fitting depression 8 or 9 which
substantially increases overall the chamber volume or the volume of cavity
2. Then the supply and removal of a medium can then take place also in the
plane of the drawing if, for instance, the same medium is to be supplied
to or removed from all chambers.
As a rule, substances like solids in a fluid are examined for the purposes
mentioned at the outset; gases in a liquid or gases or liquid in a solid
can be examined. This is true especially for immune reactions, for the
examination of enzymes or microorganisms. In examinations or analyses of
substance/mixtures, chemical or physical properties or their changes can
be ascertained with respect to one or more properties like flow, density,
surface or limit effects, especially features or particles, permeability,
friction and adhesion. In the simplest case, storage under certain
conditions such as pressure or vacuum can be examined over a definite time
or a reaction or a failure of a reaction to arrive. External influences
can be: radiation, heat treatment, application of reagents, the
measurement of the change of material properties under heat, cold, steam,
moisture or materials/particles supplied, through the application of
electrical/electrochemical or magnetic means, through the application of
sound, infrasound, ultrasound. In addition, calorimetric,
spectrophotometric or fluorometric investigations, for instance, using
reagent layers such as litmus paper can be carried out as layer 7. Heating
and/or cooling elements can be taken to the chambers in the form of
specifically annealed media in canals 10 and 11, for instance, through the
plates 3 and 5 or thermocouples, particularly Peltier elements can be
arranged at least partially in the vicinity of these cavities. Substances
can be provided with fluorescent markings, with radioactive markings or
with enzyme markings with carriers or without carriers, bound or
separable, organic or inorganic, with cells or cell fragments, gels or
others can be used for detecting microorganisms, bacteria, viruses and
others but also for detecting cancer, for determining individual
substances in the blood or for determining the pH values, of blood sugar,
of blood cholesterol or for detecting narcotics or others in the blood.
Suitable methods of analysis particularly biological/medical,
chemical/physical ones are known, especially for blood analysis, for the
analysis of sera, etc. Also examination methods or other body liquids such
as lymph liquid, urine, etc. are known, depending on whether small
particles, marked or unmarked, organic/inorganic, with or without carriers
of known type are used. Irradiation by means of X-rays but also
examinations by means of gamma rays, with visible infrared light or
ultraviolet light (optical methods) are recommended. Evaluating methods by
means of light guides are shown as examples in FIGS. 9 and 10. In the
investigation of the flow properties of substances or mixtures of
substances, it is advantageous to control, as is shown in FIG. 8, the
inflow, outflow or both (throughput) by means of microvalves 12 and 13 in
the cover or bottom 5 of block 1 with the micro properties 2. The micro
valves themselves are known per so (see, for instance, European Patent 0
250 948 A2). They are preferably arranged in the same array or in the same
matrix in the X-Y direction as the cavities 2 in the block 1 and thereby
yield a simple evaluation possibility for respective examinations. A layer
7, as in FIG. 6 can be arranged in the bottom 5. Underneath the bottom 5,
a further carrier or termination plate 14 can be arranged which can also
comprise a pickup device, for instance, photo cells in the same array
arrangement for passing on for evaluation to a micro processor (not shown
here). The lines for the supply and discharge of substances, reagents etc.
are not shown, neither are the radiation sources which advantageously
radiate in FIG. 8 from above, i.e., above the cover 3. Parts 3 and 5 can
also consist in FIG. 8 advantageously of glass, silica or silicon ceramic
or a composite silicon material and can be at least partially transparent
and have at least partially mirror surfaces. The cover or the bottom can
be replaced optionally by strips of foil of light-impervious material at
least in part; for instance, a plastic foil which brings about a
hermetically tight seal but can be pierced by a hollow needle can also be
cemented over the cover 3 if the latter contains the micro valves. Foils
or layers may be optically transparent or opaque; they can be realized as
heating layers 10 or heat sinks 11 or made for optical purposes
reflecting-nonreflecting, transparent, as filters, partially transparent
or similarly for certain wavelengths. Also carbon or diamond layers and/or
mask layers which cover the cavities at times or in part, can be used.
The microvalves can be addressed and driven in a manner known per se or be
designed as described in German Patent Application P 38 11 052.0-31. The
reaction in the cavities can then take place by movement, for instance,
piezoelectrically, magnetically, electrostatically or in similar ways.
There, a nutrient solution, a mutant, a reagent or similar substances
diluted or enriched can be dosed and the dwelling time can be controlled
by respective closing and opening of the microvalve. The heat or cooling
treatment can be carried out by means of Peltier elements, heat pipes,
Thomson-Joule coolers or similar means.
Silicon sensors are again preferred as sensors, arranged in the same array
in the lowermost layer, particularly for the examination of physical or
chemical properties such as black/white or gray value, contrast blurring,
transmission, transparency, reflection, conductivity, resistivity,
capacity, pressure, elongation, temperature volume, quantity, time, etc.
For evaluation, the measured values are passed on to a microprocessor or
microcomputer, now shown. The readout can be achieved in a manner known
per se if the evaluation takes place optically, for instance, in a manner
of the above application P 38 17 153.8-33.
The storage and documentation of the data of the measuring or test program
as well as the storage of, for instance, patient data or illness data, or
data of sera or pharmaceuticals can take place on the same chip (lowest
layer in FIGS. 8 to 10). The storage can be achieved either by means of an
optical memory, for instance, according to DE-OS 3 804 751 with amorphous
silicon as the storage medium (bubble memory) or as an integrated
semiconductor memory (DE-OS 38 17 153) or with a RAM component (P 37 01
295.9-52). As is shown in FIG. 9, it is possible in a simple manner to use
in the optical or optoelectronic evaluation, a light waveguide 15 which
passes through the micro chamber or cavity 2 in the block 1 or extends to
it.
In FIG. 9 the V-moat with its subareas 15a, 15b is changed at a 90.degree.
angle for showing subareas, but the light waveguide or optical fiber is
longitudinal within the same axis as the V-moat if it passes through the
cavity.
Preferably the light waveguide is arranged so that it can distribute light
into the cavity to evaluate changes in decoupled light under
test-influences, i.e. by measuring transmitted light intensity.
The light can be transmitted between (see FIG. 12) or through the optical
fiber or waveguide longitudinally (see FIG. 9) and/or transverse to its
axis (i.e. in an arrangement as shown in FIG. 10).
The light waveguide can be used as an information transmitter (bus) for
evaluation in a (micro-)processor or (micro-)computer as in German patent
36 19 778.
As can be seen in FIG. 9 too, the mantle of the optical fiber or waveguide
is partially destroyed or deterred in a region to get in contact with the
substance to be tested or a substrate therefore.
The mantle can be chemically etched off (if of glass) or mechanically
peeled off, by a tool (if the mantle is made of plastic).
Modifications of the embodiment according to FIG. 9 are possible in various
ways, particularly for the photoelectric or other optoelectric evaluation
not only by means of light waveguides. The light waveguides, preferably in
V-moats, are arranged fixed resting on their bottoms and not only
continuously but also cut off at an angle corresponding to the inclination
of the moat. The waveguide arrangement can be made parallel to the moat,
transversely to the moat from above or from below at a 90.degree. angle,
180.degree. or similarly. The light waveguides will bring light in and out
to the cavity and are connected for test evaluation (of the substance) to
photocells such as line sensors or arrays for the purpose of analog or
preferably digital readout. The readout can take place in lines and rows,
for instance, by means of scanners with the aid of a photoelectric line
sensor as described in DE-OS 3 804 200. Transmitters and receivers,
especially PIN diodes, can be integrated in the structural unit. The
V-angle of the moats are adjustable or variable as to slope (see DE-OS 3
613 181). Integrated optical waveguides and their design and application
are described in the journal Laser and Optoelectronik, No. 4, 1986, pages
323 to 336. On page 338 of the same journal, application of light
waveguide sensors in medicine are described.
In FIG. 10 is shown a block 1 with bottom 5 and cover 3 and with
microcavities 2 especially enlarged by recesses in the cover 3 and bottom
5, similar to FIG. 7, where however, above the microcavity 2 located in
the array arrangement, treatment openings, valves, supply and discharge
organs, windows, doping zones, etc. according to the chamber volume are
disposed in the cover 3, while in the bottom 5, for instance, an array of
photoelectric cells or a CCD array or a MOS field effect transistor is
arranged which is connected for readout and evaluation, for instance, via
the above mentioned optical or an electric bus to an evaluation unit,
especially with microprocessors, of the microcomputers. A light pen 16
scans the array line- and column-wise, for instance, in binary code
8.times.8 microcavities or cells, respectively, or 10.times.10 for direct
digital interrogation. Instead of the light pen 16, a piezoelectric, a
capacitive, a magnetic or an electric sensor can find application. The pen
16 is then suitable for applying a voltage, power or light irradiation or
something similar, through the windows 17 in the cover 3 into the chambers
2 of the block 1 for direct readout, for instance, via a CCD array in the
same arrangement as the microcavities or cells, indicated here by the CCD
cells 17'. Similarly, also a MOSFET or a RAM component can be arranged.
The readout can also be carried out with components or integrated optics,
especially contactless and two-dimensionally (see DE OS 3 605 018 or U.S.
Pat. No. 4,778,989). Instead of the light pen 16, an ion-selective
measuring electrode can also be used as a replaceable sensor element,
particularly for measuring the ion activities in liquids and at textile
surfaces. Such ion-selective measuring systems are known and are on the
market. They are based on a purely electrical evaluation system in
contrast to the embodiment of FIG. 9 which is used, for instance, for the
optical determination of the catalytic enzyme activity of a substance
sample where the change, due to the enzymic reaction of spectral
properties of an enzyme substrate or its reaction products per unit time
are picked up. The enzyme substrate is correlated with the exposed region
of a light waveguide, with which the sample substance to be measured is
brought into contact.
In the embodiment according to FIG. 10, an evaluation by means of a CCD
array is advisable, for instance, according to DE-OS 3 817 153 or by means
of semiconductors according to DE-OS 3 715 674 or by means of liquid
crystal elements such as described, for instance, in German Patent
3,602,796. With such elements, direct storage of a test or analysis result
is possible and can be interrogated in targeted fashion at any time, also
as to individual microcavities.
In FIGS. 11 and 12, optoelectronic/electronic sensors are shown which are
adapted to the properties to be examined and are generally known under the
term "biosensors". Such biosensors work generally with field-effects
transistors 18 in silicon technology. Produced together, the biosensor has
here a biological component on the surface which is connected to the gate
of a transistor. This biological component or the reaction or enzyme
substrate 19 must be able to carry out the respectively desired reaction.
Then, after the operating range is optimally adjusted, for instance, at R
by means of one or more voltage sources U1, U2, voltage can be applied to
a drain and source and corresponding changes in the event of ion activity.
The measurement can take place, according to FIG. 12, also
photoelectrically, integrated, by means of a light waveguide between the
transmitter and receivers such as diodes and lasers A biosensor of the
kind under discussion here is described in German Patent 3 634 573.
In FIG. 13, a sensor on a silicon wafer 20 is shown purely schematically,
where a sensor chip 21 is brought to reaction with a substance specimen,
for instance, a soil sample, a liquid sample, a food sample or a textile
sample with toxic substances contained therein, the percentage of which,
for instance, needs to be determined. The required amount of oxygen or the
oxygen content or something similar can also be determined. The sensor is
a conventional thermistor or a conductivity sensor. Also sound or
ultrasound or infrasound sensors are suitable if the sample is to be
subjected thereto. Miniature microphones are known for use therewith.
In FIG. 14, an embodiment of an automatic tester is shown. A microcomputer
or microprocessor takes over the control of the test procedure in
accordance with a predetermined test program. The program may contain
interchangeably external memories, for instance, in a P EPROM or an
erasable write-read memory. Patient data of the material to be tested, the
reagents, etc. are likewise stored from, upon and after the completion of
a test and the test results are likewise stored in the microcomputer or
microprocessor, especially in one for freely selectable intervention, and
the recording itself is documented, for instance, as a CCD picture, a heat
image or on magnetic tape piezoresistively, electrostatically or
ferroelectrically, etc.
In the embodiment according to FIG. 14, a film carrier 23 is shown on which
macrochips from a multiplicity of individual chips according to FIGS. 1 to
5 are cemented or are fastened detachably, wherein the film carrier has
transport perforations 24 in order to conduct the film with the
conventional film transports such as a Maltese Cross from roll to roll, is
controlled via a treatment time of the program, and from station to
station 25, i.e., here I-X. There, one or more substances are first
filled, according to a test program, into the microcavities of the chips
in station I; in station II, a reaction then takes place either with or
without treatment, and at the end of the reaction time measurement takes
place automatically and passage into the test station III, so that
optionally further tests can be carried out and the test results may be
correlated automatically with the individual cavities and optionally with
individual sample substances as well as patients. The self-documentation
and storage takes place in the microcomputer or microprocessor 22 for the
automatic test control and test application.
The invention further provides apparatus for a micromechanical heat
exchanger, especially a Joule-Thomson cooler.
According to the present state of the art, there are available on the
market various designs of miniaturized heat exchangers such as
Joule-Thomson coolers. They are all 8 distinguished by very high unit
costs.
A Joule-Thomson cooler available on the market (for instance, from the firm
Hymatik) has a very long metal helix which is wound on the surface of a
cone. The overall arrangement is contained in a Dewar housing where the
expanded gas flows back over a large area via the metal spiral between the
Dewar wall and the cone surface provided with cooling fins.
Another arrangement which was published by W. A. Little (AIP Proceedings
for Future Trends in Superconductive Electronics, page 421, University of
Virginia, Charlottesville, 1978), consists of several glass plates
cemented together, into which lateral cooling canals had been worked.
These coolers are not very effective since due to the poor thermal
conductivity of the glass, the efficiency of the heat exchanger is
limited.
The invention attacks the problem of providing a miniaturized heat
exchanger, especially a Joule-Thomson cooler which can be manufactured
cost-effectively and furnishes increased exchanger performance.
This problem is solved by the provision that in contrast to known designs,
the flow canals of a plate heat exchanger are arranged vertically in a
thin substrate. This substrate is enclosed (in sandwich fashion) by two
cover plates into which connecting canals are worked which close the
vertical canals of the substrate as seen in the cross section, to form a
meander. The individual cells of the heat exchanger are arranged in spiral
shape on the substrate (as seen from above). At the center of the
substrate there is an expansion chamber in which the main cooling output
is generated. The highly compressed gas meanders from the outside to the
inside on the heat exchanger spiral, expands in the second expansion
chamber and is then brought to the outside again counterflowwise via
canals with substantially expanded cross section, already precooling the
inflowing gas. So that the large radial temperature gradient over the
substrate can be maintained and to minimize the losses due to heat
conduction in the substrate and in the cover plates, vertical separation
canals are worked in between the individual arms of the spirals. The
overall arrangement is provided at top and bottom with two insulating
plates with heat conduction as small as possible (for instance, glass).
Glass cover plates can also be connected directly to the central plate (in
sandwich fashion).
The invention is suitable in particular for cooling infrared CCDs. As the
cooling medium, the highly compressed gas (for instance, nitrogen) is used
where the boiling point of the gas can be reached (in the central
expansion chamber of the gas) as the limit temperature.
The invention will be explained in the following, making reference to the
embodiment shown in the drawing, where
FIG. 15 shows a cross section through a heat exchanger as a Joule-Thomson
cooler in the vicinity of the high-pressure canals;
FIG. 16 shows a top view of an elementary heat exchanger cell of the
Joule-Thomson cooler in the area of the central silicon disc;
FIG. 17 shows a cross section through the Joule-Thomson cooler in the
vicinity of the low-pressure canals, and in
FIG. 18 shows an overall arrangement of the elementary heat exchanger cells
as well as of the expansion chamber at the center of the silicon disc.
In the following, one embodiment of the Joule-Thomson cooler will be
described. The overall arrangement consists of three machined silicon
discs 1, 1a, 1b which are connected to each other, and two cover plates,
for instance, of glass 3, 5 which in turn are connected to the silicon
discs according to FIG. 1.
FIG. 15 shows a cross section of the overall arrangement through the
smaller cooling canals 26. Into the upper and lower silicon discs,
depressions 27 are etched which close the canals of the central silicon
disc to form meanders. These depressions are likewise etched into (110)
silicon discs, their depths being limited automatically by the
crystallography. The etching is accomplished anisotropically by a batch
process.
Into the central silicon disc are worked vertical canals 26 which carry the
outflowing and returning gas and at the same time serve as heat exchangers
through the thin partitions. One elementary cell of this heat exchanger is
shown in FIG. 16. The inner smaller canals 26 carry the compressed
outflowing gas (for instance, typically to 50 to 100 bar). The outer large
canals 29 are connected to each other so that they form a canal with a
large cross section for the returning expanded gas. The partitions in the
outer region 28 merely have the purpose to take care of a heat exchange as
effective as possible and of mechanical stability. The more strongly
designed wall between the high and low pressure canals must take up the
entire pressure difference and at the same time make possible a good heat
transfer. In this embodiment, the specific geometry of the canals is due
to the crystalline structure of silicon, with vertical (111)--planes on
(110)--discs.
FIG. 17 shows a cross section through the outer region of the canals 29 for
the returning gas. There, the outer silicon discs 1a and 1b are etched
through completely in order to obtain a cross section as large as possible
for the meanders of the expanded gas.
The overall arrangement of the individual heat exchanger cells on the
central silicon disc is shown in FIG. 18. The cells are arranged side by
side and are brought in spiral fashion from the outer region into the
center of the disc. In the center of the disc there is an expansion
chamber 31, in which the cooling output is generated. On top of this
chamber a silicon chip or a similar semiconductor or ICs can be arranged,
for instance, directly. The individual spiral arms are thermally insulated
from each other by separation canals 32, 33.
The novel micromechanical Joule-Thomson cooler is distinguished from the
existing systems primarily due to the fact that it can be produced
substantially more cheaper by the known batch process methods of
micromechanics such as are used in the manufacture of semiconductor
components. Furthermore, due to the vertical arrangement of the cooling
canals and the frequent meanders, very high turbulence of the gas and
therefore high efficiency of the heat exchanger can be expected.
Furthermore, a semiconductor chip to be cooled can be integrated directly
into the system or overall arrangement so that the cold output is
generated directly at the chip without further partitions.
The invention is not limited to the use of a certain medium for the heat
exchange. In addition, the conduction of the media is not limited to the
embodiment shown. Heat pipes can also be used.
In the foregoing specification, the invention has been described with
reference to specific exemplary embodiments thereof. It will, however, be
evident that various modifications and changes may be made thereunto
without departing from the broader spirit and scope of the invention as
set forth in the appended claims. The specification and drawings are,
accordingly, to be regarded in an illustrative rather than in a
restrictive sense.
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