Micromachined fluid handling devices

• US 5,839,467 A
• Filed: 01/16/1996
• Issued: 11/24/1998
• Est. Priority Date: 10/04/1993
• Status: Expired due to Term

• Current Assignee: Research International Incorporated
• Original Assignee: Research International Incorporated
• Inventors: Saaski, Elric W., Lawrence, Dale M.
• Primary Examiner(s): Hepperle, Stephen M.
• Application Number:
  US08/585,951
• Time in Patent Office: 1,043 Days
• Field of Search: 137/517, 137/501, 137/505.25, 137/503
• US Class Current: 137/501
• CPC Class Codes: A61M 2205/0244 Micromachined materials, e.g. made from silicon wafers, microelectromechanical systems [MEMS] or comprising nanotechnology
• CPC Class Codes: A61M 2205/0294 Piezoelectric materials
• CPC Class Codes: A61M 5/14276 specially adapted for implantation
• CPC Class Codes: A61M 5/16881 Regulating valves on-off valves, e.g. clamps A61M39/28
• CPC Class Codes: B01D 61/18 Apparatus therefor
• CPC Class Codes: B01D 67/0058 by selective elimination of components, e.g. by leaching
• CPC Class Codes: B01D 67/0065 by anodic oxidation
• CPC Class Codes: B01D 69/02 characterised by their properties
• CPC Class Codes: B01D 71/02 Inorganic material
• CPC Class Codes: B01D 71/0213 Silicon
• CPC Class Codes: B01D 71/025 Aluminium oxide
• CPC Class Codes: F04B 43/043 Micropumps
• CPC Class Codes: F15C 5/00 Manufacture of fluid circuit elements; Manufacture of assemblages of such elements integrated circuits
• CPC Class Codes: F16K 2099/0074 using photolithography, e.g. etching
• CPC Class Codes: F16K 2099/0076 using electrical discharge machining [EDM], milling or drilling
• CPC Class Codes: F16K 2099/0078 using moulding or stamping
• CPC Class Codes: F16K 2099/0088 Implanted devices
• CPC Class Codes: F16K 99/0001 Microvalves microdevices B81B1/00; manufacture or treatment of devices or systems in or on a substrate B81C1/00; microfluidic structures B01L3/5027; micropumps F04B19/006
• CPC Class Codes: F16K 99/0015 Diaphragm or membrane valves
• CPC Class Codes: F16K 99/0026 Valves using channel deformation
• CPC Class Codes: F16K 99/0034 : Operating means specially adapted for microvalves
• CPC Class Codes: F16K 99/0057 : the fluid being the circulating fluid itself, e.g. check valves
• CPC Class Codes: G05D 7/0694 : by action on throttling means or flow sources of very small size, e.g. microfluidics microvalves F16K99/0001; microstructural devices per se B81B
• CPC Class Codes: Y10S 366/03 : Micromixers: variable geometry from the pathway influences mixing/agitation of non-laminar fluid flow
• CPC Class Codes: Y10T 137/0491 : Valve or valve element assembling, disassembling, or replacing
• CPC Class Codes: Y10T 137/2607 : With pressure reducing inlet valve
• CPC Class Codes: Y10T 137/7788 : Pressures across fixed choke
• CPC Class Codes: Y10T 137/7791 : Pressures across flow line valve
• CPC Class Codes: Y10T 137/7792 : Movable deflector or choke
• CPC Class Codes: Y10T 29/49409 : Valve seat forming
• CPC Class Codes: Y10T 29/49412 : with assembly, disassembly or composite article making
• CPC Class Codes: Y10T 29/49417 : including molding or casting
• CPC Class Codes: Y10T 29/49419 : including machining or drilling
• CPC Class Codes: Y10T 29/49826 : Assembling or joining

Abstract

The fluid handling devices are capable of accurately handling substantially continuous fluid flow rates as low as about 0.01 cc/day. The devices are so miniaturized, corrosion-resistant and non-toxic that they are suitable for being implanted in the human body; and are capable of being mass produced at costs so low, by using micromachining techniques, such as etching, that they may be considered to be disposable. The devices are either passive devices which consume no electrical energy at all, or are active devices which consume very small amounts of electrical energy. The devices are reliable because they may have as few as only two parts, only one which is a moving part; and because they may handle fluids at very low pressures. The fluid handling devices include active piezoelectrically driven membrane pumps; and passive fluid flow regulators, on-off valves, flow switches and filters.

Claims

1. A fluid flow regulator for maintaining a fluid flow from a source of fluid within a predetermined fluid flow range, wherein said regulator comprises:

a substrate;

a regulator seat located on said substrate;

a membrane comprising at least one mounting portion secured to said substrate, and a flexure extending over said regulator seat, wherein said flexure has a top surface and a bottom surface;

a regulator gap located between said flexure'"'"'s bottom surface and a top surface of said regulator seat;

fluid inlet means for permitting a fluid to enter said regulator from said source of fluid and to enter said regulator gap; and

fluid outlet means for permitting said fluid to exit from said regulator gap and to exit from said regulator;

wherein said regulator does not comprise a coiled spring that is mounted in compression between said substrate and said flexure at a position surrounding said regulator seat;

wherein, during operation of said regulator, there is a driving pressure difference of said fluid between said fluid inlet means and said fluid outlet means;

wherein, in response to an increase in said driving pressure difference, said flexure bows towards said regulator seat an increased amount, to reduce the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said increase in said driving pressure difference; and

wherein, in response to a decrease in said driving pressure difference, said flexure bows towards said regulator seat a decreased amount, to increase the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said decrease in said driving pressure difference.

5. The fluid flow regulator according to claim 1, wherein said regulator has a predetermined driving pressure difference operating range;

wherein said regulator seat is integrally formed as part of said substrate; and

wherein at least one of said fluid inlet means, said regulator seat, and said flexure are selected and sized to enable said fluid flow regulator to have, over said predetermined driving pressure difference operating range, a maximum fluid flow in the range of from about 0.01 cc/day to about 20.00 cc/day.

7. The fluid flow regulator according to claim 1, wherein said regulator has a predetermined driving pressure difference operating range;

wherein said regulator seat is integrally formed as part of said substrate; and

wherein at least one of said fluid inlet means, said regulator seat, and said flexure are selected and sized to enable said fluid flow regulator to have, over said predetermined driving pressure difference operating range, a maximum fluid flow in the range of from about 0.1 cc/day to about 2 cc/day.

18. The fluid flow regulator according to claim 1, wherein said fluid inlet means comprise a fluid inlet port;

wherein said fluid outlet means comprise a fluid outlet port; and

wherein said regulator seat, said flexure, and said regulator gap are elongated and extend from said fluid inlet port to said fluid outlet port.

22. The fluid flow regulator according to claim 18, wherein said flexure has an inlet portion which is adjacent to said fluid inlet means, and wherein at least a portion of said flexure'"'"'s inlet portion is not restrained by said substrate from being deflected towards said regulator seat when said regulator is operating within said predetermined fluid flow range.

23. The fluid flow regulator according to claim 18, wherein said regulator has a predetermined maximum said driving pressure difference;

wherein said regulator seat has a contour; and

wherein said contour at least generally approximates a contour said flexure would assume in the event said flexure was unsupported by said regulator seat and was subjected to said predetermined maximum said driving pressure difference.

2. A fluid flow regulator for maintaining a fluid flow from a source of fluid within a predetermined fluid flow range, wherein said regulator comprises:

a substrate;

a regulator seat located on said substrate;

a membrane comprising at least one mounting portion secured to said substrate, and a flexure extending over said regulator seat, wherein said flexure has a top surface and a bottom surface;

a regulator gap located between said flexure'"'"'s bottom surface and a top surface of said regulator seat;

fluid inlet means for permitting a fluid to enter said regulator from said source of fluid and to enter said regulator gap; and

fluid outlet means for permitting said fluid to exit from said regulator gap and to exit from said regulator;

wherein said regulator does not comprise a coiled spring that is mounted in compression between said substrate and said flexure at a position surrounding said regulator seat;

wherein, during operation of said regulator, there is a driving pressure of said fluid at said fluid inlet means;

wherein, in response to an increase in said driving pressure, said flexure bows towards said regulator seat an increased amount, to reduce the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said increase in said driving pressure, wherein, in response to a decrease in said driving pressure said flexure bows towards said regulator seat a decreased amount, to increase the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said decrease in said driving pressure; and

wherein said flexure'"'"'s top surface is not exposed to said fluid during operation of said fluid flow regulator.

3. A fluid flow regulator for maintaining a fluid flow from a source of fluid within a predetermined fluid flow range, wherein said regulator comprises:

a substrate;

a regulator seat located on said substrate;

a membrane comprising at least one mounting portion secured to said substrate, and a flexure extending over said regulator seat, wherein said flexure has a top surface and a bottom surface;

a regulator gap located between said flexure'"'"'s bottom surface and a top surface of said regulator seat;

fluid inlet means for permitting a fluid to enter said regulator from said source of fluid and to enter said regulator gap; and

fluid outlet means for permitting said fluid to exit from said regulator gap and to exit from said regulator;

wherein, during operation of said regulator, there is a driving pressure difference of said fluid between said fluid inlet means and said fluid outlet means;

wherein, in response to an increase in said driving pressure difference, said flexure bows towards said regulator seat an increased amount, to reduce the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said increase in said driving pressure difference; and

wherein, in response to a decrease in said driving pressure difference, said flexure bows towards said regulator seat a decreased amount, to increase the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said decrease in said driving pressure difference;

wherein said source of fluid comprises a reservoir containing a reservoir supply of said fluid;

wherein said reservoir has an outlet;

wherein, during use, said regulator is adapted to be located within said reservoir, with said regulator'"'"'s fluid outlet means located over said reservoir'"'"'s outlet; and

wherein, during use, said regulator is adapted to be immersed in said reservoir supply of said fluid, with said reservoir supply of said fluid in direct contact with said flexure'"'"'s top surface, to eliminate any need for said regulator to have a cover for said flexure'"'"'s top surface.

4. A fluid flow regulator for maintaining a fluid flow from a source of fluid within a predetermined fluid flow range, wherein said regulator comprises:

a substrate;

a regulator seat located on said substrate;

a membrane comprising at least one mounting portion secured to said substrate, and a flexure extending over said regulator seat, wherein said flexure has a top surface and a bottom surface;

a regulator gap located between said flexure'"'"'s bottom surface and a top surface of said regulator seat;

fluid inlet means for permitting a fluid to enter said regulator from said source of fluid and to enter said regulator gap; and

fluid outlet means for permitting said fluid to exit from said regulator can and to exit from said regulator;

wherein, during operation of said regulator, there is a driving pressure difference of said fluid between said fluid inlet means and said fluid outlet means;

wherein, in response to an increase in said driving pressure difference, said flexure bows towards said regulator seat an increased amount, to reduce the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said increase in said driving pressure difference; and

wherein, in response to a decrease in said driving pressure difference, said flexure bows towards said regulator seat a decreased amount, to increase the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said decrease in said driving pressure difference;

wherein said fluid flow regulator comprises a micromachined fluid flow regulator;

wherein said membrane comprises a first layer that is etchable by a first etchant, and a second layer that is not etchable by said first etchant;

wherein said second layer has a thickness about equal to said flexure; and

wherein at least part of said first layer is micromachined away by said first etchant, to produce said flexure from said membrane.

6. A fluid flow regulator for maintaining a fluid flow from a source of fluid within a predetermined fluid flow range, wherein said regulator comprises:

a substrate;

a regulator seat located on said substrate;

a membrane comprising at least one mounting portion secured to said substrate, and a flexure extending over said regulator seat, wherein said flexure has a top surface and a bottom surface;

a regulator gap located between said flexure'"'"'s bottom surface and a top surface of said regulator seat;

fluid inlet means for permitting a fluid to enter said regulator from said source of fluid and to enter said regulator gap; and

fluid outlet means for permitting said fluid to exit from said regulator gap and to exit from said regulator;

wherein, during operation of said regulator, there is a driving pressure difference of said fluid between said fluid inlet means and said fluid outlet means;

wherein, in response to an increase in said driving pressure difference, said flexure bows towards said regulator seat an increased amount, to reduce the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said increase in said driving pressure difference; and

wherein, in response to a decrease in said driving pressure difference, said flexure bows towards said regulator seat a decreased amount, to increase the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said decrease in said driving pressure difference;

wherein said regulator has a predetermined driving pressure difference operating range; and

wherein, over said predetermined driving pressure difference operating range, said regulator has a maximum fluid flow in the range of from about 0.01 cc/day to about 20.00 cc/day;

wherein said regulator seat comprises a micromachined regulator seat which has been etched into said substrate;

wherein said fluid inlet means comprises a micromachined fluid inlet means;

wherein said micromachined fluid inlet means comprises at least one micromachined area of said substrate which been etched into said substrate; and

wherein said fluid inlet means further comprises at least one corresponding portion of said membrane which extends over said micromachined area.

8. A fluid flow regulator for maintaining a fluid flow from a source of fluid within a predetermined fluid flow range, wherein said regulator comprises:

a substrate;

a regulator seat located on said substrate;

a membrane comprising at least one mounting portion secured to said substrate, and a flexure extending over said regulator seat, wherein said flexure has a top surface and a bottom surface;

a regulator gap located between said flexure'"'"'s bottom surface and a top surface of said regulator seat;

fluid inlet means for permitting a fluid to enter said regulator from said source of fluid and to enter said regulator gap; and

fluid outlet means for permitting said fluid to exit from said regulator gap and to exit from said regulator;

wherein, during operation of said regulator, there is a driving pressure difference of said fluid between said fluid inlet means and said fluid outlet means;

wherein, in response to an increase in said driving pressure difference, said flexure bows towards said regulator seat an increased amount, to reduce the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said increase in said driving pressure difference; and

wherein, in response to a decrease in said driving pressure difference, said flexure bows towards said regulator seat a decreased amount, to increase the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said decrease in said driving pressure difference;

wherein said regulator has a predetermined driving pressure difference operating range; and

wherein, over said predetermined driving pressure difference operating range, said regulator has a maximum fluid flow in the range of from about 0.1 cc/day to about 2 cc/day;

wherein said fluid flow regulator comprises a micromachined fluid flow regulator;

wherein said regulator seat comprises a micromachined regulator seat which has been etched into said substrate;

wherein said fluid inlet means comprises a micromachined fluid inlet means;

wherein said micromachined fluid inlet means comprises at least one micromachined area of said substrate which been etched into said substrate; and

wherein said fluid inlet means further comprises at least one corresponding portion of said membrane which extends over said micromachined area.

9. A fluid flow regulator for maintaining a fluid flow from a source of fluid within a predetermined fluid flow range, wherein said regulator comprises;

a substrate;

a regulator seat located on said substrate;

a membrane comprising at least one mounting portion secured to said substrate, and a flexure extending over said regulator seat, wherein said flexure has a top surface and a bottom surface;

a regulator gap located between said flexure'"'"'s bottom surface and a top surface of said regulator seat;

fluid inlet means for permitting a fluid to enter said regulator from said source of fluid and to enter said regulator gap; and

fluid outlet means for permitting said fluid to exit from said regulator gap and to exit from said regulator;

wherein said regulator does not comprise a coiled spring that is mounted in compression between said substrate and said flexure at a position surrounding said regulator seat;

wherein, during operation of said regulator, there is a driving pressure difference of said fluid between said fluid inlet means and said fluid outlet means;

wherein, in response to an increase in said driving pressure difference, said flexure bows towards said regulator seat an increased amount, to reduce the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said increase in said driving pressure difference;

wherein, in response to a decrease in said driving pressure difference, said flexure bows towards said regulator seat a decreased amount, to increase the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said decrease in said driving pressure difference;

wherein said regulator has a predetermined driving pressure difference operating range;

wherein said regulator seat has a regulator seat radial width;

wherein said regulator gap has a regulator gap height;

wherein the ratio of said regulator seat radial width to said regulator gap height is about 200;

1 and wherein when said regulator is subjected to a driving pressure difference which is in excess of said predetermined driving pressure difference operating range, said regulator reduces said fluid flow to a value which is less than said predetermined fluid flow range, as a safety measure, to help prevent fluid flows in excess of said predetermined fluid flow range.

10. A fluid flow regulator for maintaining a fluid flow from a source of fluid within a predetermined fluid flow range, wherein said regulator comprises:

a substrate;

a regulator seat located on said substrate;

a membrane comprising at least one mounting portion secured to said substrate, and a flexure extending over said regulator seat, wherein said flexure has a top surface and a bottom surface;

a regulator gap located between said flexure'"'"'s bottom surface and a top surface of said regulator seat;

fluid inlet means for permitting a fluid to enter said regulator from said source of fluid and to enter said regulator gap; and

fluid outlet means for permitting said fluid to exit from said regulator gap and to exit from said regulator;

wherein said regulator does not comprise a coiled spring that is mounted in compression between said substrate and said flexure at a position surrounding said regulator seat;

wherein, during operation of said regulator, there is a driving pressure difference of said fluid between said fluid inlet means and said fluid outlet means;

wherein, in response to an increase in said driving pressure difference, said flexure bows towards said regulator seat an increased amount, to reduce the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said increase in said driving pressure difference;

wherein, in response to a decrease in said driving pressure difference, said flexure bows towards said regulator seat a decreased amount, to increase the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said decrease in said driving pressure difference;

wherein said regulator has a predetermined driving pressure difference operating range;

wherein when said regulator is subjected to a driving pressure difference which is in excess of said predetermined driving pressure difference operating range, at least a portion of said flexure is deflected against at least a portion of said regulator seat; and

wherein said portion of said regulator seat supports said portion of said flexure, as a safety measure, to help prevent said flexure from being ruptured by said driving pressure difference which is in excess of said predetermined driving pressure difference operating range.

11. A fluid flow regulator for maintaining a fluid flow from a source of fluid within a predetermined fluid flow range, wherein said regulator comprises:

a substrate;

a regulator seat located on said substrate;

a membrane comprising at least one mounting portion secured to said substrate, and a flexure extending over said regulator seat, wherein said flexure has a top surface and a bottom surface;

a regulator gap located between said flexure'"'"'s bottom surface and a top surface of said regulator seat;

fluid inlet means for permitting a fluid to enter said regulator from said source of fluid and to enter said regulator gap; and

fluid outlet means for permitting said fluid to exit from said regulator gap and to exit from said regulator;

wherein, during operation of said regulator, there is a driving pressure difference of said fluid between said fluid inlet means and said fluid outlet means;

wherein, in response to an increase in said driving pressure difference, said flexure bows towards said regulator seat an increased amount, to reduce the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said increase in said driving pressure difference; and

wherein, in response to a decrease in said driving pressure difference, said flexure bows towards said regulator seat a decreased amount, to increase the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said decrease in said driving pressure difference;

wherein said membrane'"'"'s mounting portion is anodically bonded to said substrate.

12. A fluid flow regulator for maintaining a fluid flow from a source of fluid within a predetermined fluid flow range, wherein said regulator comprises:

a substrate;

a regulator seat located on said substrate;

a membrane comprising at least one mounting portion secured to said substrate, and a flexure extending over said regulator seat, wherein said flexure has a top surface and a bottom surface;

a regulator gap located between said flexure'"'"'s bottom surface and a top surface of said regulator seat;

fluid inlet means for permitting a fluid to enter said regulator from said source of fluid and to enter said regulator gap; and

fluid outlet means for permitting said fluid to exit from said regulator gap and to exit from said regulator;

wherein, during operation of said regulator, there is a driving pressure difference of said fluid between said fluid inlet means and said fluid outlet means;

wherein, in response to an increase in said driving pressure difference, said flexure bows towards said regulator seat an increased amount, to reduce the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said increase in said driving pressure difference; and

wherein, in response to a decrease in said driving pressure difference, said flexure bows towards said regulator seat a decreased amount, to increase the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said decrease in said driving pressure difference;

wherein said regulator comprises at least one exposed portion which is exposed to said fluid during operation of said regulator;

wherein said regulator further comprises a corrosion-resistant layer on at least part of said exposed portion; and

wherein said corrosion resistant layer is anodically bonded to said exposed portion.

13. The fluid flow regulator according to claim 12, wherein said corrosion-resistant layer comprises an oxide of a transition metal selected from the group consisting of titanium and zirconium.

14. The fluid flow regulator according to claim 12, wherein said corrosion-resistant layer is located on at least part of said regulator seat'"'"'s top surface;

and wherein said corrosion-resistant layer on said regulator seat'"'"'s top surface serves the dual functions of helping to prevent corrosion of said regulator seat'"'"'s top surface, and helping to prevent said flexure'"'"'s bottom surface from being anodically bonded to said regulator seat'"'"'s top surface. said regulator seat and said regulator gap each have a length, a width, and a length to width ratio; and

wherein said length to width ratio of at least one of said regulator seat and said regulator gap is selected to be in the range of from about 5;

1 to 1000;

1.

15. A fluid flow regulator for maintaining a fluid flow from a source of fluid within a predetermined fluid flow range, wherein said regulator comprises:

a substrate;

a regulator seat located on said substrate;

a membrane comprising at least one mounting portion secured to said substrate, and a flexure extending over said regulator seat, wherein said flexure has a top surface and a bottom surface;

a regulator gap located between said flexure'"'"'s bottom surface and a top surface of said regulator seat;

fluid inlet means for permitting a fluid to enter said regulator from said source of fluid and to enter said regulator gap; and

fluid outlet means for permitting said fluid to exit from said regulator gap and to exit from said regulator;

wherein, during operation of said regulator, there is a driving pressure difference of said fluid between said fluid inlet means and said fluid outlet means;

wherein, in response to an increase in said driving pressure difference, said flexure bows towards said regulator seat an increased amount, to reduce the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said increase in said driving pressure difference; and

wherein, in response to a decrease in said driving pressure difference, said flexure bows towards said regulator seat a decreased amount, to increase the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said decrease in said driving pressure difference;

wherein said fluid inlet means comprises at least two inlet channels;

wherein at least one of said inlet channels is a sealed inlet channel, which is sealed to prevent any flow of said fluid through said sealed inlet channel; and

wherein said predetermined fluid flow range may be at least partially selected by selecting how many of said inlet channels is a sealed inlet channel.

16. A fluid flow regulator for maintaining a fluid flow from a source of fluid within a predetermined fluid flow range, wherein said regulator comprises:

a substrate;

a regulator seat located on said substrate;

a membrane comprising at least one mounting portion secured to said substrate, and a flexure extending over said regulator seat, wherein said flexure has a top surface and a bottom surface;

a regulator gap located between said flexure'"'"'s bottom surface and a top surface of said regulator seat;

fluid inlet means for permitting a fluid to enter said regulator from said source of fluid and to enter said regulator gap; and

fluid outlet means for permitting said fluid to exit from said regulator gap and to exit from said regulator;

wherein, during operation of said regulator, there is a driving pressure difference of said fluid between said fluid inlet means and said fluid outlet means;

wherein, in response to an increase in said driving pressure difference, said flexure bows towards said regulator seat an increased amount, to reduce the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said increase in said driving pressure difference; and

wherein, in response to a decrease in said driving pressure difference, said flexure bows towards said regulator seat a decreased amount, to increase the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said decrease in said driving pressure difference;

wherein said fluid inlet means comprise an inlet channel;

wherein at least a portion of said inlet channel follows a course; and

wherein said course comprises a course selected from the group consisting of circular, spiral and sinuous.

17. A fluid flow regulator for maintaining a fluid flow from a source of fluid within a predetermined fluid flow range, wherein said regulator comprises:

a substrate;

a regulator seat located on said substrate;

a membrane comprising at least one mounting portion secured to said substrate, and a flexure extending over said regulator seat, wherein said flexure has a top surface and a bottom surface;

a regulator gap located between said flexure'"'"'s bottom surface and a top surface of said regulator seat;

fluid inlet means for permitting a fluid to enter said regulator from said source of fluid and to enter said regulator gap; and

fluid outlet means for permitting said fluid to exit from said regulator gap and to exit from said regulator;

wherein said regulator does not comprise a coiled spring that is mounted in compression between said substrate and said flexure at a position surrounding said regulator seat;

wherein, during operation of said regulator, there is a driving pressure difference of said fluid between said fluid inlet means and said fluid outlet means;

wherein, in response to an increase in said driving pressure difference, said flexure bows towards said regulator seat an increased amount, to reduce the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said increase in said driving pressure difference;

wherein, in response to a decrease in said driving pressure difference, said flexure bows towards said regulator seat a decreased amount, to increase the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said decrease in said driving pressure difference;

wherein said fluid outlet means comprises a laser drilled outlet port;

wherein said laser drilled outlet port is automatically given a curved, non-cylindrical, venturi-like configuration by said laser when it is drilled by said laser, for better fluid flow through said outlet port;

wherein said outlet port has an outlet port inlet and an outlet port outlet;

wherein at said outlet port has a length measured between said outlet port inlet and said outlet port outlet; and

wherein at least a majority of said outlet port'"'"'s length comprises said curved, non-cylindrical, venturi-like configuration.

19. A fluid flow regulator for maintaining a fluid flow from a source of fluid within a predetermined fluid flow range, wherein said regulator comprises:

a substrate;

a regulator seat located on said substrate;

a membrane comprising at least one mounting portion secured to said substrate, and a flexure extending over said regulator seat, wherein said flexure has a top surface and a bottom surface;

a regulator gap located between said flexure'"'"'s bottom surface and a top surface of said regulator seat;

fluid inlet means for permitting a fluid to enter said regulator from said source of fluid and to enter said regulator gap; and

fluid outlet means for permitting said fluid to exit from said regulator gap and to exit from said regulator;

wherein, during operation of said regulator, there is a driving pressure difference of said fluid between said fluid inlet means and said fluid outlet means;

wherein, in response to an increase in said driving pressure difference, said flexure bows towards said regulator seat an increased amount, to reduce the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said increase in said driving pressure difference; and

wherein, in response to a decrease in said driving pressure difference, said flexure bows towards said regulator seat a decreased amount, to increase the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said decrease in said driving pressure difference;

wherein said regulator seat, said flexure, and said regulator gap are elongated and extend from said fluid inlet means to said fluid outlet means;

wherein at least a portion of said regulator seat, said flexure and said regulator gap follow a course from said fluid inlet means to said fluid outlet means, and wherein said course comprises a course selected from the group consisting of circular, spiral and sinuous.

20. A fluid flow regulator for maintaining a fluid flow from a source of fluid within a predetermined fluid flow range, wherein said regulator comprises:

a substrate;

a regulator seat located on said substrate;

a membrane comprising at least one mounting portion secured to said substrate, and a flexure extending over said regulator seat, wherein said flexure has a top surface and a bottom surface;

a regulator gap located between said flexure'"'"'s bottom surface and a top surface of said regulator seat;

fluid inlet means for permitting a fluid to enter said regulator from said source of fluid and to enter said regulator gap; and

fluid outlet means for permitting said fluid to exit from said regulator gap and to exit from said regulator;

wherein, during operation of said regulator, there is a driving pressure difference of said fluid between said fluid inlet means and said fluid outlet means;

wherein, in response to an increase in said driving pressure difference, said flexure bows towards said regulator seat an increased amount, to reduce the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said increase in said driving pressure difference; and

wherein, in response to a decrease in said driving pressure difference, said flexure bows towards said regulator seat a decreased amount, to increase the size of said regulator gap and to tend to hold said fluid flow within said predetermined fluid flow range, despite said decrease in said driving pressure difference;

wherein said regulator seat, said flexure, and said regulator gap are elongated and extend from said fluid inlet means to said fluid outlet means;

wherein said regulator gap has a height measured between said regulator seat and said flexure, a length, a width, and a length to width ratio; and

wherein said length to width ratio of said regulator gap is selected to be in the range of from about 5;

1 to 1000;

1.

21. The fluid flow regulator according to claim 20, wherein said length to width ratio of at least one of said regulator seat and said regulator gap is about 20:

1.

24. A flow switch for selectively controlling a fluid flow from a source of fluid, wherein said flow switch comprises:

a substrate, a single membrane, and a switch gap;

wherein said substrate comprises a mounting portion, an inlet switch seat, and outlet port means for permitting said fluid to flow from said inlet switch seat and out of said flow switch;

wherein said membrane comprises a mounting portion, a resilient flexure which extends over at least a portion of said inlet switch seat, and an inlet port means in said single membrane;

wherein said inlet port means in said single membrane is located over said inlet switch seat, and is for providing a fluid path from a source of said fluid to said inlet switch seat;

wherein, at all times during operation of said flow switch when said fluid is flowing from said outlet port, all of said fluid that flows from said outlet port is supplied only by said inlet sort means in said single membrane;

wherein said switch gap is located between said flexure and said switch seat;

wherein said membrane and said substrate are secured together at their respective said mounting portions;

wherein, when a positive driving pressure difference of said fluid across said flow switch, which is less than a predetermined driving pressure difference switch point, is applied to a top surface of said flexure and to said inlet port means, said fluid flows continuously into said flow switch through said inlet port means, flows continuously radially outwardly across a top surface of said inlet switch seat through said switch gap; and

flows continuously out of said flow switch through said outlet port means;

wherein, at said predetermined driving pressure difference switch point, said flexure automatically collapses against said inlet switch seat, to automatically close said switch gap, switch off said flow switch, and stop said fluid flow through said flow switch; and

wherein, at a driving pressure difference across said flow switch which is less than said driving pressure difference switch point, said resilient flexure automatically moves away from said inlet switch seat, to automatically open said switch gap, switch said flow switch back on, and permit said fluid to flow continuously through said flow switch once again.

28. The flow switch according to claim 24, wherein said flow switch has a predetermined driving pressure difference switch point;

wherein at least one of said membrane, said flexure, said inlet port means in said membrane, and said inlet switch seat are selected and sized to enable said flow switch to have, at pressures less than said predetermined driving pressure difference switch point, a fluid flow in the range of from about 0.01 cc/day to about 20.00 cc/day.

29. The flow switch according to claim 24, wherein said flow switch has a predetermined driving pressure difference switch point;

wherein at least one of said membrane, said flexure, said inlet port means in said membrane, and said inlet switch seat are selected and sized to enable said flow switch to have, at pressures less than said predetermined driving pressure difference switch point, a fluid flow of about fluid flow in the range of from about 0.1 cc/day to about 2 cc/day.

35. The flow switch according to claim 24, wherein said outlet port means comprises a laser drilled outlet port;

and wherein said laser drilled outlet port is automatically given a venturi-like configuration by said laser when it is drilled by said laser, for better fluid flow through said outlet port.

25. A flow switch for selectively controlling a fluid flow from a source of fluid, wherein said flow switch comprises:

a substrate, a membrane, and a switch gap;

wherein said substrate comprises a mounting portion, an inlet switch seat, and outlet port means for permitting said fluid to flow from said inlet switch seat and out of said flow switch;

wherein said membrane comprises a mounting portion, a resilient flexure which extends over at least a portion of said inlet switch seat, and an inlet port means, which is located over said inlet switch seat, for providing a fluid path from a source of said fluid to said inlet switch seat;

wherein said switch gap is located between said flexure and said switch seat;

wherein said membrane and said substrate are secured together at their respective said mounting portions;

wherein, when a positive driving pressure difference of said fluid across said flow switch, which is less than a predetermined driving pressure difference switch point, is applied to a top surface of said flexure and to said inlet port means, said fluid flows continuously into said flow switch through said inlet port means, flows continuously radially outwardly across a top surface of said inlet switch seat through said switch gap; and

flows continuously out of said flow switch through said outlet port means;

wherein, at said predetermined driving pressure difference switch point, said flexure automatically collapses against said inlet switch seat, to automatically close said switch gap, switch off said flow switch, and stop said fluid flow through said flow switch; and

wherein, at a driving pressure difference across said flow switch which is less than said driving pressure difference switch point, said resilient flexure automatically moves away from said inlet switch seat, to automatically open said switch gap, switch said flow switch back on, and permit said fluid to flow continuously through said flow switch once again;

wherein said source of fluid comprises a reservoir containing a reservoir supply of said fluid;

wherein said reservoir has an outlet;

wherein, during use, said flow switch is adapted to be located within said reservoir, with said flow switch'"'"'s outlet port means located over said reservoir'"'"'s outlet; and

wherein, during use, said flow switch is adapted to be immersed in said reservoir supply of said fluid, with said reservoir supply of said fluid in direct contact with said flexure'"'"'s top surface, to eliminate any need for said flow switch to have a cover for said flexure'"'"'s top surface.

26. A flow switch for selectively controlling a fluid flow from a source of fluid, wherein said flow switch comprises:

a substrate, a membrane, and a switch gap;

wherein said substrate comprises a mounting portion, an inlet switch seat, and outlet port means for permitting said fluid to flow from said inlet switch seat and out of said flow switch;

wherein said membrane comprises a mounting portion, a resilient flexure which extends over at least a portion of said inlet switch seat, and an inlet port means, which is located over said inlet switch seat, for providing a fluid path from a source of said fluid to said inlet switch seat;

wherein said switch gap is located between said flexure and said switch seat;

wherein said membrane and said substrate are secured together at their respective said mounting portions;

wherein, when a positive driving pressure difference of said fluid across said flow switch, which is less than a predetermined driving pressure difference switch point, is applied to a top surface of said flexure and to said inlet port means, said fluid flows continuously into said flow switch through said inlet port means, flows continuously radially outwardly across a top surface of said inlet switch seat through said switch gap; and

flows continuously out of said flow switch through said outlet port means;

wherein, at said predetermined driving pressure difference switch point, said flexure automatically collapses against said inlet switch seat, to automatically close said switch gap, switch off said flow switch, and stop said fluid flow through said flow switch; and

wherein, at a driving pressure difference across said flow switch which is less than said driving pressure difference switch point, said resilient flexure automatically moves away from said inlet switch seat, to automatically open said switch gap, switch said flow switch back on, and permit said fluid to flow continuously through said flow switch once again;

wherein said flow switch comprises a micromachined flow switch;

wherein said membrane comprises a first layer that is etchable by a first etchant, and a second layer that is not etchable by said first etchant;

wherein said second layer has a thickness about equal to said flexure; and

wherein at least part of said first layer is micromachined away by said first etchant, to produce said flexure from said membrane.

27. The flow switch according to claim 26, wherein both of said membrane'"'"'s first and second layers are etchable by a second etchant;

and wherein at least part of at least one of said first and second layers is micromachined away by said second etchant, to produce said inlet port means in said membrane.

30. A flow switch for selectively controlling a fluid flow from a source of fluid, wherein said flow switch comprises:

a substrate, a membrane, and a switch gap;

wherein said substrate comprises a mounting portion, an inlet switch seat, and outlet port means for permitting said fluid to flow from said inlet switch seat and out of said flow switch;

wherein said membrane comprises a mounting portion, a resilient flexure which extends over at least a portion of said inlet switch seat, and an inlet port means, which is located over said inlet switch seat, for providing a fluid path from a source of said fluid to said inlet switch seat;

wherein said switch gap is located between said flexure and said switch seat;

wherein said membrane and said substrate are secured together at their respective said mounting portions;

wherein, when a positive driving pressure difference of said fluid across said flow switch, which is less than a predetermined driving pressure difference switch point, is applied to a top surface of said flexure and to said inlet port means, said fluid flows continuously into said flow switch through said inlet port means, flows continuously radially outwardly across a top surface of said inlet switch seat through said switch gap; and

flows continuously out of said flow switch through said outlet port means;

wherein, at said predetermined driving pressure difference switch point, said flexure automatically collapses against said inlet switch seat, to automatically close said switch gap, switch off said flow switch, and stop said fluid flow through said flow switch; and

wherein, at a driving pressure difference across said flow switch which is less than said driving pressure difference switch point, said resilient flexure automatically moves away from said inlet switch seat, to automatically open said switch gap, switch said flow switch back on, and permit said fluid to flow continuously through said flow switch once again;

wherein said flow switch comprises a micromachined flow switch;

wherein said outlet port means comprises a outlet cavity in said substrate;

wherein said inlet switch seat is a micromachined inlet switch seat;

wherein said outlet cavity is a micromachined outlet cavity; and

wherein at least one of said micromachined inlet switch seat and said micromachined outlet cavity have been etched into said substrate.

31. A flow switch for selectively controlling a fluid flow from a source of fluid, wherein said flow switch comprises:

a substrate, a membrane, and a switch gap;

wherein said substrate comprises a mounting portion, an inlet switch seat, and outlet port means for permitting said fluid to flow from said inlet switch seat and out of said flow switch;

wherein said membrane comprises a mounting portion, a resilient flexure which extends over at least a portion of said inlet switch seat, and an inlet port means, which is located over said inlet switch seat, for providing a fluid path from a source of said fluid to said inlet switch seat;

wherein said switch gap is located between said flexure and said switch seat;

wherein said membrane and said substrate are secured together at their respective said mounting portions;

wherein, when a positive driving pressure difference of said fluid across said flow switch, which is less than a predetermined driving pressure difference switch point, is applied to a top surface of said flexure and to said inlet port means, said fluid flows continuously into said flow switch through said inlet port means, flows continuously radially outwardly across a top surface of said inlet switch seat through said switch gap; and

flows continuously out of said flow switch through said outlet port means;

wherein, at said predetermined driving pressure difference switch point, said flexure automatically collapses against said inlet switch seat, to automatically close said switch gap, switch off said flow switch, and stop said fluid flow through said flow switch; and

wherein, at a driving pressure difference across said flow switch which is less than said driving pressure difference switch point, said resilient flexure automatically moves away from said inlet switch seat, to automatically open said switch gap, switch said flow switch back on, and permit said fluid to flow continuously through said flow switch once again;

wherein said substrate'"'"'s and membrane'"'"'s mounting portions are anodically bonded to each other.

32. A flow switch for selectively controlling a fluid flow from a source of fluid, wherein said flow switch comprises:

a substrate, a membrane, and a switch gap;

wherein said substrate comprises a mounting portion, an inlet switch seat, and outlet port means for permitting said fluid to flow from said inlet switch seat and out of said flow switch;

wherein said membrane comprises a mounting portion, a resilient flexure which extends over at least a portion of said inlet switch seat, and an inlet port means, which is located over said inlet switch seat, for providing a fluid path from a source of said fluid to said inlet switch seat;

wherein said switch gap is located between said flexure and said switch seat;

wherein said membrane and said substrate are secured together at their respective said mounting portions;

wherein, when a positive driving pressure difference of said fluid across said flow switch, which is less than a predetermined driving pressure difference switch point, is applied to a top surface of said flexure and to said inlet port means, said fluid flows continuously into said flow switch through said inlet port means, flows continuously radially outwardly across a top surface of said inlet switch seat through said switch gap; and

flows continuously out of said flow switch through said outlet port means;

wherein, at said predetermined driving pressure difference switch point, said flexure automatically collapses against said inlet switch seat, to automatically close said switch gap, switch off said flow switch, and stop said fluid flow through said flow switch; and

wherein, at a driving pressure difference across said flow switch which is less than said driving pressure difference switch point, said resilient flexure automatically moves away from said inlet switch seat, to automatically open said switch gap, switch said flow switch back on, and permit said fluid to flow continuously through said flow switch once again;

wherein said flow switch comprises at least one exposed portion which is exposed to said fluid during operation of said flow switch;

wherein said flow switch further comprises a corrosion-resistant layer on at least part of said exposed portion; and

wherein said corrosion-resistant layer is anodically bonded to said exposed portion.

33. The flow switch according to claim 32, wherein said corrosion-resistant layer comprises an oxide of a transition metal selected from the group consisting of titanium and zirconium.

34. The flow switch according to claim 32, wherein said corrosion-resistant layer is located on at least part of said inlet switch seat'"'"'s top surface;

and wherein said corrosion-resistant layer on said inlet switch seat'"'"'s top surface serves the dual functions of helping to prevent corrosion of said inlet switch seat'"'"'s top surface, and helping to prevent a bottom surface of said flexure from being anodically bonded to said inlet switch seat'"'"'s top surface.