JP2003510552A - Fractal absorber for heat pipes with a wide range of thermal radiation absorption capacity - Google Patents

Abstract

(57) Abstract: A heat pipe (105) having nanoparticles (160).

Description

Detailed Description of the Invention

[0001]

[Related application]

This application is related to US provisional patent application No. 60 / 156,195 (title of invention: Nanopartic).
le Structures With Receptors for Raman Spectroscopy; Inventor: David I. K
reimer, Ph.D., Oleg A. Yevin, Ph.D., Thomas H. Nufert; Filing date: 1999
September 27), US Provisional Patent Application No. 60 / 156,145 (Title of Invention: Addr
essable Arrays Using Morphology Dependent Resonance for Analyte Detectio
n; Inventor: Oleg A. Yevin, Ph.D., David I. Kreimer, Ph.D .; Filing date: 19
September 27, 1999) and US Provisional Patent Application No. 60 / 156,471 (Title of Invention: Fractal Absorber for Hear Pipes with Broad Range Heat Radiation Absorp
tivity; Inventor: Oleg Yevin, Thomas H. Nufert and David I. Kreimer). The disclosure of each of these US provisional patent applications is hereby incorporated by reference.

[0002]

BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION The present invention relates to the manufacture of heat pipes with improved heat radiation absorption. In particular, the invention relates to the manufacture of heat pipes with surfaces for absorbing and radiating heat via radiative heat transfer. More particularly, the present invention relates to the manufacture of heat pipes having a surface coated with a nano-level particle (hereinafter "nanoparticle") structure for absorbing broadband electromagnetic radiation.

DESCRIPTION OF RELATED ART Many useful mechanical and electrical processes result in the dissipation or dissipation of energy in the form of heat. This heat is often undesirable. I mean,
This is because the temperature of the system rises. Heat pipes are used to transfer heat from one location to another to prevent the system from warming up. In addition, when using solar radiation as the energy source, raising the temperature of the solar radiation absorbing element is the first step in the energy conversion. In the next stage, the heat pipe
Often used to rapidly transfer heat from solar radiation absorbing elements to other elements in these systems.

In general, heat pipes transfer heat more quickly than solid copper rods of the same diameter. Heat pipes transfer heat with low losses and do not require the input of an additional energy source, such as a compressor. This ability to transfer heat without the need for energy input supports a wide range of technical applications for heat pipes. I. heat pipe

FIG. 1 illustrates the principle of operation of a typical heat pipe 100, which is a hollow metal tube 105 sealed at both ends, with a wick or capillary structural member 135 covering the inner surface of the tube. Covering. The tube is filled with a volatile fluid 140. When one end of the pipe 110 heats up as indicated by Q _in , the volatile fluid 140 evaporates at this end of the pipe. The vapor expands and moves to the other cold end 120 of the tube (
(Shown by the curved arrow), where condensation of the volatile fluid occurs and heat dissipation (Q _out ) occurs. The condensate returns by capillary action to the hot end of the pipe via wick path 135. Thus, the cycle of evaporation at the hot end where heat energy is absorbed from the ambient environment and condensation at the cold end releasing heat to the ambient environment forms the basis of heat transfer in the heat pipe. .

[0006] Typically, the outer tube is made of a material having a high thermal conductivity, such as copper. These materials absorb and / or dissipate heat under contact and convection heat transfer conditions. However, when a radiation-based heat transfer mechanism is involved, high heat transfer rates alone are not sufficient to achieve the desired high heat transfer efficiency, so other factors can be used to improve the efficiency of this method. Good. These requirements require (1) the outer surface of the pipe to absorb and / or emit electromagnetic radiation in a wide wavelength range, and (2) the efficiency of heat transfer between the bulk of the tube material and the outer surface. Need to be relevant. One method of manipulating the heat absorption and / or heat dissipation properties of a surface is by making the surface structure with micron-sized geometric holes and coating the pipe with a material with the desired emission spectrum, such as tungsten. (See US Pat. No. 5,932,029 to Stone, et al., The contents of which are incorporated herein by reference. ).

SUMMARY OF THE INVENTION It is thus an object of the present invention to develop a heat pipe with excellent performance of absorbing and emitting electromagnetic radiation in a wide spectral range due to the nanoparticle structure coating the outer surface. . Another object of the invention is to produce nanoparticle structures with a wide range of endothermic and / or heat dissipation properties. Yet another object of the present invention is to produce a nanoparticle structure with a specific range of heat absorption and / or heat dissipation properties. Another object of the invention is to develop a method for the attachment of nanoparticle structures to surfaces.

These and other objectives are met by the design and manufacture of heat pipes coated with a particulate structure that allows effective absorption and / or emission of electromagnetic radiation. In this specification, these heat pipes are referred to as "radiative heat pipes". In certain embodiments of the invention, the surface is modified by changing the size and the distance between nanoparticles by manipulating the properties of the fractal structure by photomodification, the shape of the particles, the material of the particles and ( Alternatively, a material capable of absorbing and / or emitting light in a desired spectral range is formed by changing the material of the heat conducting layer and / or the material of the heat pipe tube.

In another embodiment, a series of chemical reactions may be performed to form particles with specific spatial interrelationships, which are used to generate the particle structure. In one set of chemical reactions, the metal particles may be reacted with a molecular linker. These reactions can go to near completion when the affinity of the reactants is high enough and the ratio of the reactants is controlled. The products of these reactions include various suspensions of a characteristic sized particle structure predetermined by the length of the linker.

Another feature of the invention is the use of raised linkers of various lengths that maintain the characteristic size of the particle structure. Standard length linkers allow some control over particle structure generation and manipulation of particle structure properties. In the first binding reaction, the metal particles can be positioned at a certain distance from each other by using a relatively short fixed length linker molecule. In the subsequent reaction, the length of the linker may be increased to increase the length between the pair of particles. By using the set of products described herein, for example, broadband absorption and (
Alternatively, or in the case of the production of heat pipes with emission or, if desired, narrow band absorption and / or emission, the particle structure can be obtained in a controlled manner. The present invention will be described in connection with that particular embodiment. Other objects, features and advantages of the present invention will be apparent with reference to the specification and drawings.

Detailed Description of Embodiments Definitions The following terms are used herein. The term "fractal" as used herein means a structure composed of various elements and having a certain relationship (ie, scale invariance) between the observation scale and a large number of elements. By way of example, a continuous line is a one-dimensional object. Plane is 2
It is a three-dimensional object, and the volume is a three-dimensional object. However, the dimension is less than 1 if there are gaps in the line and it is not a continuous line. For example, if 1/2 of the line is missing, then the fractal dimension is 1/2. Similarly, if the points on the plane are missing, the fractal dimension of the plane is 1-2. If half of the points on the plane are missing, the fractal dimension is 1.5. Furthermore, if 1/2 of the solid line is missing, the fractal dimension is 2.5. In scale-invariant structure, the structure of the object is
It looks the same regardless of the size of the area observed. Fractal structures are thus a type of ordered structure that distinguishes it from random structures that are not regularly arranged.

[0012]   As used herein, the term "fractal associate" has at least about 1
Fractal Associate, consisting of 00 individual, interrelated particles
The lower limit is set by the size of each individual particle, which is the size of the fractal associate.
Limited size that determines scale invariance within the observed area, which is capped by the law
Means the structure of.   As used herein, the term "fractal dimension" refers to the following equation: N∝R ^D In this formula, R is the observation area, N is the number of particles, and D is
It is a fractal dimension. Thus, with a non-fractal solid, the viewing radius is doubled.
Then, the number of particles observed in the volume is 2³Double. However, to this
In the corresponding fractal, if the observation radius is doubled, the number of observed particles is
1/2³Less than double.

As used herein, the term “fractal particle associate” refers to the number of particles per unit area (dependent variable) or the number of particles per unit area varying non-linearly with an observational scale (independent variable). It means a large number of arranged particles. The term "linker", as used herein, is a molecular complex that is capable of binding to atoms, molecules, components or surfaces and that has two or more chemical groups that allow the particles to be linked together to form groups of particles. Means The simplest linker connects two particles to each other. A branched linker can connect multiple particles to each other. The term “ordered structure” as used herein means a structure that is not random.

As used herein, the term “particle structure” means a group of individual particles that are associated with each other in such a way that an electric field can be strengthened in response to incident electromagnetic radiation. Examples of particles include metals, metal-coated polymers and fullerenes. Also included within the meaning of the term "particle structure" is a composite having particles embedded on or within a film or dielectric surface. As used herein, the term "percolation time point" refers to a time point on a conductive surface or medium at which the surface exhibits an increase in conductance measured via the surface or bulk conductance of the medium. One way to measure surface or "sheet" conductance is to apply an electrical probe to the surface.

As used herein, the term “Raman signal” means a Raman spectrum or part of a Raman spectrum. The term "Raman spectrum singular value" as used herein means the value obtained as a result of the analysis of the Raman spectrum obtained for the analyte under the detection conditions. Raman spectrum singular values include, but are not limited to, Raman band frequencies, Raman band intensities, Raman band widths, bandwidth ratios, band intensity ratios and / or combinations thereof.

The term “Raman spectroscopy” as used herein refers to a technique for determining the relationship with the intensity of scattered electromagnetic radiation as a function of the frequency of the scattered electromagnetic radiation. As used herein, the term "Raman spectrum" means the relationship with the intensity of scattered electromagnetic radiation as a function of the frequency of the scattered electromagnetic radiation. As used herein, the term "random structure" means a structure that is neither ordered nor ordered and is not fractal. The random structure appears uniform regardless of the observation point and the scale, in which case the observation scale contains at least a few particles.

As used herein, the term “resonance” refers to incident, scattered and / or emitted electromagnetic radiation and electrons that can be excited by electromagnetic radiation and increase the strength of the electric field of the electromagnetic radiation. It means the interaction with the surface carrying. As used herein, the term "resonance domain" means the region within or near the grain structure where enhancement of the electric field of incident electromagnetic radiation occurs. The term "reduced diameter" as used herein refers to the relationship between particles within a mating structure that have the same ratio of particle diameters (reduction factor) regardless of the size of the particles. As used herein, the term "plane-enhanced Raman spectroscopy (SERS)" refers to a field of application of Raman spectroscopy in which the intensity of Raman scattering is enhanced in the presence of the enhanced surface.

As used herein, the term “plane enhanced resonance Raman spectroscopy (SERRS)” refers to
It refers to the field of application of Raman spectroscopy when the Raman signal of the analyte is enhanced in the presence of the enhancement surface (see definition of SERS) and the absorption band of the analyte overlaps the wavelength of the incident electromagnetic radiation.

Examples of the Invention The present invention involves the use of a particle structure in the absorptive and / or radiative portion of a heat pipe. The nanoparticle structure can be applied to the outer surface of the heat pipe, thereby effectively absorbing or releasing heat energy. By increasing the absorption efficiency by the outer surface of the heat pipe, the heat energy can be more easily transferred to the inside of the heat pipe, thus increasing the evaporation rate of the volatile fluid inside the heat pipe. The increased evaporation of the volatile fluid can increase the flow rate of the evaporated fluid and increase the heat flow from the absorbent portion of the heat pipe to the radiative portion of the heat pipe. Increasing the heat flow to the radiative section can increase the heat loss from that section of the pipe. In another embodiment of the present invention, the radiant portion of the heat pipe may also be coated with a particulate structure to increase heat loss from the radiant portion of the heat pipe. Structures desirable for use in accordance with the methods of the present invention include small particle structures (referred to herein as particle structures), and these particle structures include a subset of fractal associations. The grain structure may be characterized as having a physical or chemical structure that allows vibrations of electrons to be in resonance with the incoming and outgoing electromagnetic radiation.

I. Manufacture of Particle Structures Particle structures desired for use in accordance with the present invention may include any structure capable of absorbing or emitting electromagnetic signals over a wide wavelength range. The following description of the metal particle structure is not intended to limit the scope of the invention, but is for illustration purposes only. Other structures, including fractal structures, may also be desirable.

A. Manufacture of Metal Particles To make metal particles according to some embodiments of the present invention, Applicants may generally use methods known in the art. US Pat. No. 5,567,628 to Tarcha et al. Is hereby incorporated by reference. The metal colloid may consist of a noble metal, in particular elemental gold or silver, copper, platinum, palladium and other metals known to be broadband absorbing and emitting in the desired spectral range. Generally, to make a metal colloid, a dilute solution containing a metal salt is chemically reacted with a reducing agent. Examples of the reducing agent include ascorbate, citrate, borohydride, hydrogen gas and the like. Chemical reduction of metal salts can produce elemental metals in solution, which combine to form a colloidal solution containing relatively spherical metal particles.

Example 1 Preparation of Gold Colloid, Fractal Structure In one embodiment of the present invention, to make a solution of gold nuclei, a 0.01% solution of NaAuCl ₄ is made in water with vigorous stirring. Add 1 milliliter (ml) of 1% sodium citrate solution. After mixing for 1 minute, 0.075% NaBH ₄ and 1
1 ml of a solution containing% sodium citrate is added with vigorous stirring.
The reaction is allowed to proceed for 5 minutes, creating gold nuclei with an average diameter of about 2 nanometers. The solution containing the gold nuclei may be frozen at 4 ° C. until needed. This solution may be used as is, and a gold nucleus-containing solution 30μl 1% sodium citrate solution 0.4 ml, vigorously in a solution of 1% HAuCl ₄ 3H ₂ O diluted with H ₂ O in 100ml It may be used to produce larger size particles (eg, about 50 nanometer diameter particles) by rapid addition with stirring.
The mixture is boiled for 15 minutes and then cooled to room temperature. During cooling, the particles in the solution can form a fractal structure. The colloidal and / or fractal particle structure thus produced can be stored in a dark bottle.

Depositing reinforcing particles on the surface of a dielectric material, including glass, can produce a film capable of enhancing electromagnetic signals. Such films are as thin as about 10 nanometers. In particular, the electric field enhancement distribution on the surface of such films can be inhomogeneous. Such a strengthened region is a resonance region. Such regions may be particularly useful for positioning receptors for analyte binding, detection. Manufacture of reinforced structures in the case of films or grain structures embedded in dielectric materials
One way is to treat the surface until the "percolation point" appears. Methods for measuring sheet resistance and body resistance are well known in this technical field.

Example 2 Production of Metal Particles and Fractal Structures Using Laser Ablation In addition to the liquid phase synthesis described above, laser ablation is used to produce metal particles. A piece of metal foil with a low concentration of noble gas (for example, helium, neon, argon,
Place in chamber containing xenon or krypton). Exposure of metal foils to laser light or other heat sources causes evaporation of metal atoms, which
When suspended in the chamber, they spontaneously aggregate to form fractal structures or other particle structures as a result of random diffusion. These methods are well known in the art.

B. Production of Film Containing Particles To produce a substrate containing metal colloidal particles according to one embodiment of the present invention, colloidal metal particles are placed on a quartz slide as described in Example 1 or 2. It can be deposited on top. Other films incorporating random or non-fractal ordered structures can be made in a similar fashion.

Example 3 Production of Quartz Slide Containing Gold Fractal Structure A quartz slide (2.5 cm × 0.8 cm × 0.1 cm) was HC for several hours.
l: Clean in a mixture of HNO ₃ (3: 1). The slides were then washed with deionized H ₂ O (Millipore Corporation) to a resistance of about 18 MΩ, then CH ₃ OH.
Wash with. The slide is then immersed for 18 hours in a solution of aminopropyltrimethoxysilane diluted 1: 5 with CH ₃ OH. The slides are then thoroughly washed with CH ₃ OH (spectrophotometric grade) and deionized H ₂ O before immersion in the colloidal gold solution described above. During this time, gold colloid particles may precipitate and adhere to the surface of the quartz slide. After 24 hours, colloid derivatization is complete. Once attached, the binding of colloidal gold nanocomposites to the quartz surface is strong and nearly irreversible. During this procedure, the UV and / or visible light absorbance spectra of such guide slides are used to assess the quality and reproducibility of the derivatization procedure. The manufacturing process is monitored using an electron microscope to evaluate the density of the colloidal coating, the distribution of gold colloidal particles on the surface and the size of the gold colloidal particles.

C. Aggregation of Particles to Form Particle Structures According to other embodiments of the present invention, several methods can be used to form particle structures. It is known that metal colloids can be deposited on surfaces to form fractal structures with a fractal dimension of about 1.8 upon aggregation. Safono
v et al., Spectral Dependence of Selective Photomodification in Fractal
Aggregates of Colloidal Particles, Physical Review Letters 80 (5), 1102-1
All 105 (1998) are incorporated herein by reference. FIG. 1 shows one particle structure suitable for use with the method of the present invention. The particles are arranged in a scale-invariant manner, which promotes the formation of resonant regions upon irradiation with laser light. In addition to fractal structures, non-fractal ordered and random structures can be generated. These different types of structures may have desirable properties for enhancing the signal associated with the detection of analytes using electromagnetic radiation.

To create a non-fractal ordered structure, chemical linkers with sequentially different lengths can be used, for example, as described in more detail below. In addition, linkers of the same size can be used to generate ordered structures that may be useful for certain applications. In some embodiments of the invention, particles can be attached to each other to form a structure having resonant properties. Generally, it may be desirable for the particles to be spherical, ellipsoidal or rod-shaped. For elliptical particles, it may be desirable for the particles to have a long axis (x), another axis (y) and a third axis (z). In general, x is
It may be desirable to have from about 0.05 times the wavelength (λ) of the incident electromagnetic radiation to be used to about 1. In the case of a rod, x is less than about 4λ, or less than about 3λ, or less than about 2λ, less than about 1λ in other embodiments, and less than about 1 / 2λ in another embodiment. May be desirable. The ends of the rod may be flat, tapered, rectangular, or have other shapes that can facilitate resonance.

In the case of a two-particle structure, the x-dimension is such that the particle pair is less than about 4λ, or less than about 2λ, in other embodiments less than about 1λ, and in another embodiment less than about 1 / 2λ. May be desirable to have. For two-dimensional structures, particles, rods, rod + particle pairs can be used together. The arrangement of these elements may be randomly distributed or may have a distribution density that depends on the observation scale in a non-linear manner.

In other embodiments, the rods may be end-to-end interconnected to form an elongated structure that may enhance resonant properties. For three-dimensional structures, ordered nested particles or chemical particle arrays can be used in combination with fractal structures or ordered nested arrays of chemical linkers.

In another embodiment of tertiary structure, a suspension of particles may be desirable. In some of these embodiments, the airborne particles can have dimensions in the range of about 1/2 to about 1 millimeter (mm).

Using the principles of the present invention, researchers or developers are not meant to be limiting,
Absorption rate of electromagnetic radiation by particle elements, properties of selected surfaces, number of resonance regions, resonance characteristics, wavelength of electromagnetic radiation indicating resonance enhancement, porosity of particle structure and total structure of particle structure (but not intended to be limiting, Many needs can be met, including the choice of structure (including fractal dimensions).

1. Photoaggregation Photoaggregation can be used to produce particle structures with properties that may be desirable for use in broadband electromagnetic radiation absorbers. Irradiation of fractal metal nanocomposites with laser pulses with energies above a certain threshold allows for selective photomodification, a process that can form "dichroic holes" in the absorption spectrum near the laser wavelength ( Safonov et al.
, Physical Review Letters 80 (5): 1102-1105 (1998) are incorporated herein by reference). Polymers doped with both silver and gold colloids, metal aggregates,
For films produced by laser evaporation of metal targets, selective photomodification of geometric structures can be observed.

One theory for the formation of selective photomodification is that the localization of photoexcitation in fractal structures is common in random nanocomposites. According to this theory, the localization of selective photomodification in fractals can occur due to the scale-invariant distribution of highly polarisable particles (monomers). As a result, small groups of particles with different localized configurations can interact with incident light independently of each other and resonate at different frequencies to produce different regions (here, "optical modes"). Called). According to the same theory, the optical mode formed by the interaction between the monomers in the fractal is smaller than the optical wavelength of the incident light,
It is then localized in regions that may be smaller than the size of the particles within the colloid. The frequencies of the optical modes can span a wider spectral range than the absorption bandwidth of the monomer associated with plasmon resonance at the surface. However, other theories can explain the effect of photomodification of fractal structure. Therefore, the present invention is not limited to any particular operability theory.

Photodenaturation of silver fractal aggregates can occur in areas as small as about 24 × 24 × 48 nm ³ (Safbnov et at, Physical Review Letters 80 (5): 1102-1 105 (
1998) is hereby incorporated by reference in its entirety). The energy absorbed by the fractal medium can be localized to a decreasing number of monomers with increasing laser wavelength. As the energy absorbed in the resonant region increases, the temperature at those locations can increase. Light with a wavelength of 550 nanometers with a power of 11 mJ / cm ² can be generated at a temperature of about 600 K (Safonov et al., Ph.
All of ysical Review Letters 80 (5): 1102-1105 (1998) are incorporated herein by reference). At this temperature (about half the melting point of silver), colloidal sintering occurs (Safo
nov at al, Id, all incorporated herein by reference), by which stable fractal nanocomposites can be formed.

As used in the present invention, photoaggregation is from about 400 nanometers to about 2000.
It can be achieved by exposing the metal colloid on the surface to a pulse of incident light having a wavelength in the nanometer range. In another embodiment, this wavelength is about 45
It can range from 0 nanometers to about 1079 nanometers. The intensity of the incident light is
It can range from about 5 mJ / cm ² to about 20 mJ / cm ² . In another example, the incident light may have a wavelength of 1079 nanometers with an intensity of 11 mJ / cm ² .

Fractal agglomerates that are particularly useful in the present invention can be made from metal particles having dimensions ranging from about 10 nanometers to about 100 nanometers in diameter, and in another embodiment about 50 nanometers in diameter. A typical fractal structure of the present invention is
The aggregate area, which can be composed of up to about 1000 particles and is typically used for large scale arrays, can have a size of about 100 μm × 100 μm. FIG. 2 shows a particle structure that is photoaggregated and suitable for use with the method of the present invention. The local fusion area of metal particles can be observed (in the circle).

II. Particle Structure In certain embodiments of the present invention, the particle structure of the present invention may have certain properties of fractal. A fractal is a structure that displays a self-similar pattern. Self-similarity means that the entire structure is scale-invariant in that it looks similar over a wide range of magnifications. Fractal-like structures are widespread everywhere, for example clouds. Fractal objects can also be created artificially. For example, when arranging a landscape of metal surfaces in a self-similar triangle or other shape, such a fractal object can serve as a so-called "fractal antenna". Such an antenna enables a wider radio wave transmission / reception range than an antenna having a more regular structure.

As a similar example, when metal particles having a diameter of about 1/10 of the wavelength of incident light are arranged on the surface in the form of a fractal-like structure, such a fractal surface absorbs light over a wide optical range. Can be displayed (SHalaev VM, et al. J. Nonlinear O
All of ptical Physics & Materials 7 (1): 13 1-152 (1998) are incorporated herein by reference). In this case, a fractal-like structure is obtained due to the fact that the number of particles per surface area decreases with increasing surface area scale. One theory that explains the absorbance of such fractal surfaces is the interference of oscillating dipole moments induced by electromagnetic waves in individual particles.

According to one theory, incident photons can induce an electric field across the particle, causing mobile electrons in the metal to move with the frequency of the incident electromagnetic field. Such a collective movement is called a "plasmon wave" here. According to one theory, collective vibrations of electrons are caused by strong dipolar and polypolar interactions of plasmon waves in metal particles in a fractal structure. Since almost all distances and orientations of metal particles can be present in such fractal systems, a large number of possible "resonant cavities" are formed in such structures. Here, the term "resonant cavity" means an arrangement of particles that provides a plurality of resonant states for the wavelength of incident light. Each such cavity absorbs and / or emits electromagnetic waves at a certain set of wavelengths. Since many different resonant cavities can exist within the nanoparticle structure, many different frequencies can be absorbed and / or emitted by this structure. Therefore, the combined ability of all these cavities to resonate within a wide range of wavelengths gives rise to the wide absorption band of such fractal structures.

Chemical reduction of metal colloidal solutions, laser ablation of surfaces, surface etching, film annealing are used, for example, to produce fractal-like structures (Kreimer et al., United States Provisional Patent Application,
titled "Nanoparticle Structures With Receptors for Raman Spectroscopy",
Inventors: David I. Kreimer, Ph.D., Oleg A Yevin, Ph.D, Thomas H. Nufert
, filing Date: September 27, 1999 and "SHalaev et. al. (199k), all incorporated herein by reference). Typically, a fractal-like structure is fa
It can be obtained by allowing the r-from-equilibrium system to achieve a low energy state. In such systems, fractal-like structures can form spontaneously. In addition to fractal structures, other types of particle structures can also result in the enhanced absorptive and / or emissive properties of the present invention. The production of a grain structure applicable to the surface of heat pipes is described below.

1. Chemically Induced Synthesis of Particle Structures In certain embodiments of the invention, nanoparticle structures can be produced by chemical methods. First, the metal particles can be manufactured according to the method described above, or the metal particles can be purchased from a commercial supplier (NanoGram Inc, Fremont, Calif.). The particles can then be linked together to form a primary structure, eg, a pair of particles. The primary structures can then be joined together to form secondary structures, eg, pairs of particle pairs. Finally, a tertiary fractal structure can be produced by bonding secondary structures together.

In another embodiment of the present invention, the fractal array of metal particles may be formed using chemical methods. Once the metal colloid particles are prepared, each particle can be attached to a linker molecule via a thiol or other type of suitable chemical bond. Linker molecules can then be attached to each other and connect adjacent colloidal particles to each other. The distance between the particles is a function of the total length of the linker molecule. Here, it may be desirable to choose a stoichiometric ratio of particles to linker molecules. Also, if too few linker molecules are used, the array of particles may be too loose or may not be formed at all. Conversely, if the linker molecule-to-particle ratio is too high, the array will either be too tight or will even tend to form crystalline structures (not random), which will tend to promote Raman resonances. It will be.

In general, it may be desirable to perform the ligation procedure sequentially. In that case, the first step involves adding linker molecules to the individual particles under conditions that do not allow cross-linking of the particles to each other. For example, such a linker may include an oligonucleotide having a reactive group on only one end. During this first step, the reactive end of the oligonucleotide may be attached to the metal particle, thereby forming the first particle-linker species and having the free end of the linker. The ratio of linker molecules to particles can be chosen depending on the number of linker molecules to be attached to the particles. The second linker may be attached to another group of particles in different reaction chambers. Thereby, a second linker particle species is generated, where again the linker may have free ends.

After these reactions proceed, different linker / particle species are mixed with each other,
Linkers can be attached to each other to form "particle pairs" that are linked by linker molecules. As an example, Figures 2a-2c illustrate a method of making the fractal structure of the present invention. In Figure 2a, metal particles 10 are formed using the method previously described. The short linker 20 has a chemically active end capable of binding to the metal particle 10. For example, the linker 20 has a sulfhydryl (“S
H ") group. Upon bonding, the metal particles 10 bond with the SH end of the linker 20 to form the particle pair 30.

FIG. 2b illustrates a process that can be used to form clusters of particle pairs. Particle pairs 30 react with intermediate length linkers 40 to form clusters 50. FIG. 2c illustrates a process that can be used to form the nanoscale fractal structure of the present invention. Clusters 50 react with long linkers 60 to form nanoscale fractal structures 70.

The linker molecule can be chosen to obtain any desired length. Typically, organic component polymers may also be useful. For example, conjugation can be performed with aryl dithiol or diisonitrile molecules. Alternatively, any active ingredient that can be used to attach the linker to the metal particles can be used. It may be desirable to use the above types of aryl linkers with nucleic acids or other types of linker molecules. The linker can have a central region with an ethylbenzene component, where n is a number between 1 and about 10,000.

Generally, the length ratio for each consecutive linker pair is from about 2 to about 20.
Can range. Alternatively, the ratio of the length of consecutive linker pairs is about 3 to.
It can range from about 10, and in other embodiments about 5. For example, for a tertiary manufacturing process involving linkers 1, 2, 3 (L1, L2, L3, respectively), it may be desirable for the ratio L1: L2: L3 to be in the range of about 1: 2: 4. Alternatively, the ratio may be about 1: 5: 25, and in another embodiment the ratio may be about 1: 20: 400. In other embodiments, the ratio of L1, L2 and the ratio of L2, L3 need not be the same. Therefore, in one embodiment, the ratio of L1: L2: L3 is 1: 3 :.
It could be 20, or 1:20:40. Under these conditions, structures with any desired porosity can be produced. In general, the size of the nanoscale structure should have an average dimension in the range of about 20 nanometers to about 10,000 nanometers. In another example, these dimensions can be in the range of about 50 nanometers to about 300 nanometers, and in other embodiments, in the range of about 100 to about 200 nanometers, and yet another embodiment. In an example, it can be about 150 nanometers.

For certain applications of the invention, it may be desirable to use nanoparticles with a variety of different diameters. Thus, in the same reaction, a nanoparticle structure can be produced starting with particles having a diameter of about 20 nanometers to about 10,000 nanometers. In addition, the shape of the particles may be modified to improve heat transfer. For example, rod-shaped particles are about 100: 1 to 2: 1, or about 50: 1 to about 5 :.
1, in other embodiments, it may have a length to diameter ratio of about 20: 1 to about 10: 1. In addition to applications in spectroscopy (SERS, surface plasmon resonance spectroscopy, fluorescence, surface-enhanced infrared absorption spectroscopy and other spectroscopic techniques), fractal-like structures made from metal particles can also be used as wide wavelength filters or antennas. Can be used.

In addition, such a system may be used in a wide variety of heat exchange methods and devices. For example, the material can be made from metal particles arranged in a fractal-like structure. These materials will have excellent heat absorption and release properties. These films can be used with heat pipes for heat removal and can be integrated with materials for use in building structures, engine cooling systems, microchip cooling, space engineering. In addition, the invention can be used in clothing materials for military purposes for night-vision infrared detection (night vision).

2. Manufacture of Nested Particle Related Materials Nested particle related materials can be manufactured by selecting colloidal solutions of metal gold particles having uniform sizes, diameters of 10 nanometers, 40 nanometers, and 240 nanometers, respectively. Multiple 10 nanometer gold particles with a linker (eg, DNA) can be attached thereto. When a plurality of 40 nanometer particles are produced, each has a respective linker, eg DNA, corresponding to the DNA linker of the 10 nanometer particles. A mixture of linker-derived 10,40 nanometer particles is placed in solution and allowed to react with each other. DNA linkers bind to each other to form a primary nested structure.

The secondary nested particle structure consists of a plurality of primary particles surrounding a particle that is larger (eg, 240 nanometers) than either of the first two particles. Better order nested particles can be obtained by heating the primary or secondary particle mixture to a temperature below about 100 ° C. and then cooling.

3. Fabrication of Surfaces with Non-Random Grain Structures To fabricate the heat pipes of the present invention, chemically induced or nested grain structures can be deposited on the heat conducting surface. The particle structure may desirably be attached to the surface using a conductive polymer. When the surface thus coated is exposed to electromagnetic radiation, some of the incident light can be absorbed by the grain structure and transmitted inside the heat pipe. The heat inside the pipe is then transferred to another location along the heat pipe (
(For example, a cooler environment exists), which can dissipate the heat of the heat pipe to the surrounding environment.

In certain other embodiments of the present invention, a suspension nested particle structure or other particle structure may be used. These structures can be deposited first and then polymers can be used to enhance the attachment of the particle structures and enhance the durability of surface covering.

III. Thermally Conductive Polymers Thermally and environmentally stable polymers, such as polyaniline-based or polypyrrole-based composites, are thermally conductive (see EFONIX patent).
Other composites capable of depositing metal particles on metal surfaces are also known (incorporated by reference in its entirety in US Pat. No. 5,925,467).

Example 4: Heat Pipe Embodying a Fractal Endotherm FIG. 3 shows a portion 110 of an embodiment 300 of the invention, in which a heat pipe 105 similar to that shown in FIG. , Partially covered with grain structure. The heat sink portion 110 includes a heat pipe 105, a core element 135 having a volatile fluid 130. A portion of the volatile fluid 140 is shown adjacent the wick 135. Heat pipe 105
Surrounding is embedded a layer of thermally conductive polymer 145 having metal particles 150. A region 160 surrounding the thermally conductive polymer layer 145 and comprising a nanoparticle structure
There is.

FIG. 4 illustrates the present invention 400 having a grain structure at the heat absorbing end 110 of the heat pipe.
Shows a specific example of. The heat pipe 105 has a core element 135 containing a volatile fluid 130. The exterior of the heat pipe is shown as having a layer of thermally conductive polymer 145, which is coated with regions of grain structure 160. Heat (Qi
n) is absorbed by the grain structure 160 at the heat absorber section 110 of the heat pipe and is transferred to the heat pipe 105 by the polymer layer 145. The heat vaporizes the volatile fluid 130 in the core region 135 to produce the vaporized fluid 140,
It flows to the discharge end 120 of the heat pipe. At the discharge end 120 of the heat pipe, the evaporated fluid 140 condenses and releases heat. The liquid flows into the core structure 135,
It is sucked back into the heat absorbing portion 110 of the heat pipe.

FIG. 5 shows an embodiment of the invention 500 having a grain structure at both the heat absorption end 110 and the emission end 120 of the heat pipe. The same features described above in connection with FIG. 4 apply to FIG. Furthermore, at the discharge end 120, the thermally conductive polymer 1
Forty-six layers surround the heat pipe 105. A layer of grain structure 161 is applied to the outer surface of thermally conductive polymer layer 146. The type of thermally conductive polymer 146 need not be the same as the thermally conductive polymer 145, and the particle structure 161 is
It does not have to be the same as zero. The heat transferred from the absorption end 110 of the heat pipe 500 can be carried to the discharge end 120. At the discharge end 120, the evaporating fluid 140 condenses and releases the heat “Qout”. This heat can flow to the nanoparticle structure 161 through the thermally conductive polymer layer 146, which can dissipate the nanoparticle structure 161.

In another embodiment of the invention, the particle structure may be directly attached to the surface of the heat pipe without an intervening layer of thermally conductive polymer. For example, photolithographic methods can be used to deposit the grain structure. Such a method is incorporated by reference in the United States Provisional Patent Application, titled
"Nanoparticle Structures With Receptors for Raman Spectroscopy". Invent
ors: David I. Kreimer, PhD., Oleg A. Yevin, Ph.D., Thomas H. Nufert. Fil
ing Date: September 27, 1999.

In addition, laser ablation can be used to produce particle structures directly on the heat pipe. All of these methods are incorporated herein by reference.
e United States Provisional Patent Application titled "Nanoparticle Stru
ctures With Receptors for Raman Spectroscopy ". Inventors: David I. Kreim
er, Ph.D., Oleg A. Yevin, Ph.D., Thomas H. Nufert. Filing Date: Septembe
r 27, 1999.

The construction is useful for the manufacture of improved heat pipes used to transfer heat from one point to another under radiative heat transfer conditions. Improved heat transfer is mechanical,
Equipment such as electrical equipment can be kept within the desired operating temperature range. Therefore, the nanoparticle structure of the present invention can be used for solar heating devices and can also protect the equipment from being overheated by thermal radiation including solar radiation.

[Brief description of drawings]

[Figure 1]   It is a figure which shows the example of a conventional heat pipe and the design of a heat transfer mechanism.

Figure 2a   FIG. 3 is a schematic diagram of a set of chemical reactions for producing the particle structure of the present invention.

Figure 2b   FIG. 3 is a schematic diagram of a set of chemical reactions for producing the particle structure of the present invention.

[Fig. 2c]   FIG. 3 is a schematic diagram of a set of chemical reactions for producing the particle structure of the present invention.

[Figure 3]   It is a figure which shows the detailed design of the radiation absorption edge part of the heat pipe of this invention.

FIG. 4 shows a heat pipe of the present invention designed to collect a wide spectral range of electromagnetic radiation, convert this energy into heat, and transfer this heat to the cold end of the pipe.

FIG. 5 is a diagram showing an example design of a heat pipe of the present invention capable of both absorbing heat and radiating heat via radiative heat transfer.

─────────────────────────────────────────────────── ─── Continued front page    (31) Priority claim number 60 / 156,471 (32) Priority date September 27, 1999 (September 27, 1999) (33) Priority claiming countries United States (US) (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE), OA (BF, BJ , CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, K E, LS, MW, MZ, SD, SL, SZ, TZ, UG , ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, BZ, C A, CH, CN, CR, CU, CZ, DE, DK, DZ , EE, ES, FI, GB, GD, GE, GH, GM, HU, ID, IL, IN, IS, JP, KE, KG, K P, KR, KZ, LC, LK, LR, LS, LT, LU , LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, PT, RO, RU, SD, S E, SG, SI, SK, SL, TJ, TM, TR, TT , TZ, UA, UG, UZ, VN, YU, ZA, ZW (72) Inventor Nuffert Thomas H             United States California             94596 Walnut Creek F               Oak Road 2633 (72) Inventor Climber David Eye             United States California             94703 Berkeley Dwight Way             1841

Claims (15)

[Claims] 1. A heat pipe, comprising: a pipe; and a particle structure provided on the pipe and having a preselected electromagnetic absorption band. 2. The heat pipe according to claim 1, further comprising a heat conductor provided between the pipe and the particle structure. 3. The heat pipe according to claim 1, further comprising a wick and a liquid that transfers heat from one end of the pipe to another end of the pipe. 4. The heat pipe according to claim 1, wherein the particle structure is a fractal structure. 5. The heat pipe according to claim 1, wherein the particle structure is a mating particle structure. 6. The heat pipe according to claim 1, wherein the particle structure comprises particles and a chemical linker. 7. The method according to claim 1, further comprising a plurality of grain structures.
The heat pipe according to any one of to 6. 8. The heat pipe according to claim 1, wherein the particle structure is attached to the pipe by a polymer. 9. The heat conductor is a polymer.
Heat pipe described. 10. The heat pipe according to claim 1, wherein the particle structure has a predetermined electromagnetic emission band. 11. The heat pipe according to claim 4, wherein the fractal structure has a predetermined electromagnetic absorption band. 12. The heat pipe according to claim 4, wherein the fractal structure has a predetermined electromagnetic emission band. 13. The heat pipe according to claim 4, further comprising a heat conductor provided between the pipe and the fractal structure. 14. The heat pipe according to claim 4, further comprising a wick and a liquid that transfers heat from one end of the pipe to another end of the pipe. 15. A method for transferring heat from a heat source to a heat sink, the method comprising: a pipe having a plurality of particle structures, a heat conductive layer provided between the plurality of particle structures, a wick, and a liquid for transferring heat. A method, comprising: providing, exposing a first end of the pipe to the heat source, and exposing a second end of the pipe to the heat sink.