Porous silicon structures with high surface area/specific pore size

• US 5,882,496 A
• Filed: 02/27/1997
• Issued: 03/16/1999
• Est. Priority Date: 02/27/1997
• Status: Expired due to Fees

• Current Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Raley, Norman F., Northrup, M. Allen, Yu, Conrad M.
• Primary Examiner(s): Valentine, Donald R.
• Application Number:
  US08/807,152
• Time in Patent Office: 747 Days
• Field of Search: 210/502.1, 210/506, 96/11 SP, 96/11, 55/523, 204/601, 204/605
• US Class Current: 204/601
• CPC Class Codes: B01D 2325/04 Characteristic thickness
• CPC Class Codes: B01D 39/2006 the material being particulate
• CPC Class Codes: B01D 57/02 by electrophoresis treatment of water, waste water, sewage or sludge by electrophoresis C02F1/469; electrophoretic production of compounds or non-metals C25B7/00; investigating or analysing materials by using electrophoresis G01N27/26
• CPC Class Codes: B01D 67/0044 by chemical reaction
• CPC Class Codes: B01D 71/0213 Silicon
• CPC Class Codes: B01J 19/0093 Microreactors, e.g. miniaturised or microfabricated reactors laboratory containers with capillary fluid transport in microfabricated channels or chambers B01L3/5027
• CPC Class Codes: B01J 2219/00828 Silicon wafers or plates
• CPC Class Codes: B01J 2219/00873 Heat exchange
• CPC Class Codes: B01J 2219/00905 Separation
• CPC Class Codes: B01J 2219/00912 by electrophoresis
• CPC Class Codes: B01L 2300/0645 Electrodes
• CPC Class Codes: B01L 2300/0681 Filter
• CPC Class Codes: B01L 2300/1827 using resistive heater
• CPC Class Codes: B01L 2400/0421 electrophoretic flow
• CPC Class Codes: B01L 2400/0442 thermal energy, e.g. vaporisation, bubble jet
• CPC Class Codes: B01L 2400/0688 surface tension valves, capillary stop, capillary break
• CPC Class Codes: B01L 3/502707 characterised by the manufacture of the container or its components by shaping or joining plastic parts B29C59/00, B29C65/00; by laminating B32B37/00; manufacture of microstructural devices in general B81C
• CPC Class Codes: B01L 3/50273 characterised by the means or forces applied to move the fluids micropumps F04B19/006, of the membrane type F04B43/043
• CPC Class Codes: B01L 3/502738 characterised by integrated valves microvalves F16K99/0001
• CPC Class Codes: G01N 27/44743 Introducing samples
• CPC Class Codes: G01N 27/44791 : Microapparatus sample containers with integrated microfluidic structures B01L3/5027
• CPC Class Codes: Y10S 977/832 : having specified property, e.g. lattice-constant, thermal expansion coefficient
• CPC Class Codes: Y10S 977/888 : Shaping or removal of materials, e.g. etching

Abstract

Fabrication and use of porous silicon structures to increase surface area of heated reaction chambers, electrophoresis devices, and thermopneumatic sensor-actuators, chemical preconcentrates, and filtering or control flow devices. In particular, such high surface area or specific pore size porous silicon structures will be useful in significantly augmenting the adsorption, vaporization, desorption, condensation and flow of liquids and gasses in applications that use such processes on a miniature scale. Examples that will benefit from a high surface area, porous silicon structure include sample preconcentrators that are designed to adsorb and subsequently desorb specific chemical species from a sample background; chemical reaction chambers with enhanced surface reaction rates; and sensor-actuator chamber devices with increased pressure for thermopneumatic actuation of integrated membranes. Examples that benefit from specific pore sized porous silicon are chemical/biological filters and thermally-activated flow devices with active or adjacent surfaces such as electrodes or heaters.

Claims

1. In a device through which fluid or gas is adapted to pass, the improvement comprising:

at least one porous silicon member having pores in the range of less than about 1 μ

m,

said porous silicon member defining a section of a crystalline silicon member.

2. The improvement of claim 1, wherein said porous silicon member pores are in the range of about 10 nm to about 1 μ

m.

3. The improvement of claim 1, wherein said porous silicon member has a thickness of about 50 μ

m.

4. The improvement of claim 1, additionally including a coating of material on said porous silicon member.

5. The improvement of claim 4, wherein said coating is composed of material which undergoes desorption-upon heating and adsorption upon cooling.

6. The improvement of claim 5, additionally including means for heating and cooling the porous silicon member.

7. The improvement of claim 1, wherein said porous silicon member contains absorbed amounts of gas or fluid.

8. The improvement of claim 1, additionally including means for heating said porous silicon member.

9. The improvement of claim 1, wherein said porous silicon member is positioned in a chamber and contains a desorbable material, and additionally including means for heating said porous silicon member causing desorption of said material creating an increase in pressure in said chamber.

10. The improvement of claim 9, wherein said chamber is constructed to include a thin section, and increase in pressure in said chamber causes deflection of said thin section.

11. The improvement of claim 1, wherein said porous silicon member defines an interface between two-analysis devices, and additionally including means for heating said porous silicon member for controlling flow between said two analysis devices.

12. The improvement of claim 11, wherein said two analysis devices comprise a PCR and an electrophoresis device.

13. The improvement of claim 12, wherein at least one of said analysis devices includes a plurality of spaced porous silicon members.

14. The improvement of claim 13, wherein the plurality of spaced porous silicon members is provided with a heater means or positive/negative electrode means.

15. The improvement of claim 11, wherein said porous silicon member is located in one of said analysis devices which is constructed of two plates bonded together and constructed to form at least one electrophoresis channel therein.

16. The improvement of claim 1, wherein said porous silicon member is formed by processing a section of the crystalline silicon member to produce pores therein in a range of about 5 nm to about 100 nm.

17. The improvement of claim 1, wherein said porous silicon member defines at least one wall surface of a chemical reactor thereby providing a greater surface area in said chemical reactor.

18. The improvement of claim 1, wherein said porous silicon member is located in a crystalline silicon member and provided with thin film electrodes to produce electromotive force through pores of said porous silicon which are utilized as electrophoresis channels.

19. A porous silicon member defining a section of a crystalline silicon member and having pores in the range of about 1-10 nm to about 1 μ

m.

20. The porous silicon member of claim 19, constructed by processing said section of said crystalline silicon member.

21. The porous silicon member of claim 19, wherein said pores contain adsorbed or coated materials, said porous silicon member being provided with heating means.

22. The porous silicon member of claim 19, additionally including a heater means therefore, whereupon change in temperature changes flow of a material through said porous silicon member.

23. The porous silicon member of claim 19, in combination with devices selected from the group consisting of a microfabricated chemical reactor, a micro-valve, a micro chemical preconcentrator, a dual analysis system, an actuator, and filter system, and an electrophoresis system.