# US 5,705,070 A · Micromachined filters

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- Number: US 5,705,070 A
- Document ID: US5705070A
- Status: Granted
- Kind: A
- Application number: 08/445,403
- Filed: 1995-05-19
- Granted: 1998-01-06
- Earliest claimed: 1993-10-04
- Assignees: Research International, Inc.
- Inventors: Elric W. Saaski; Dale M. Lawrence
- Web page: https://patentgrep.com/patent/US5705070A

## CPC

- B01D 71/025: {Aluminium oxide}
- A61M 5/16881: {Regulating valves}
- B01D 61/18: Apparatus therefor
- B01D 67/0058: {by selective elimination of components, e.g. by leaching}
- B01D 67/0065: {by anodic oxidation}
- B01D 69/02: characterised by their properties
- B01D 71/0213: {Silicon}
- F04B 43/043: {Micropumps}
- F15C 5/00: Manufacture of fluid circuit elements; Manufacture of assemblages of such elements {integrated circuits}
- 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)}
- F16K 99/0015: {Diaphragm or membrane valves}
- F16K 99/0026: {Valves using channel deformation}
- F16K 99/0057: {the fluid being the circulating fluid itself, e.g. check valves}
- 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)}
- A61M 5/14276: {specially adapted for implantation}
- A61M 2205/0244: Micromachined materials, e.g. made from silicon wafers, microelectromechanical systems [MEMS] or comprising nanotechnology
- A61M 2205/0294: Piezoelectric materials
- F16K 99/0034: {Operating means specially adapted for microvalves}
- F16K 2099/0074: {using photolithography, e.g. etching}
- F16K 2099/0076: {using electrical discharge machining [EDM], milling or drilling}
- F16K 2099/0078: {using moulding or stamping}
- F16K 2099/0088: {Implanted devices}
- Y10S 366/03: Micromixers: variable geometry from the pathway influences mixing/agitation of non-laminar fluid flow
- Y10T 29/49409: Valve seat forming
- Y10T 29/49412: with assembly, disassembly or composite article making
- Y10T 29/49417: including molding or casting
- Y10T 29/49419: including machining or drilling
- Y10T 29/49826: Assembling or joining
- Y10T 137/0491: Valve or valve element assembling, disassembling, or replacing
- Y10T 137/2607: With pressure reducing inlet valve
- Y10T 137/7788: Pressures across fixed choke
- Y10T 137/7791: Pressures across flow line valve
- Y10T 137/7792: Movable deflector or choke
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- A61M: DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY (introducing media into or onto the bodies of animals A61D7/00; means for inserting tampons A61F13/26; devices for administering food or medicines orally A61J; containers for collecting, storing or administering blood or medical fluids A61J1/05); DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY (surgery A61B; chemical aspects of surgical articles A61L); DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR {(Electrotherapy, e.g. producing anaesthesia by the use of alternating or intermittent currents A61N1/36021)}
- F04B: POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS (machines for liquids, or pumps, of rotary-piston or oscillating-piston type F04C; non-positive-displacement pumps F04D; pumping of fluid by direct contact of another fluid or by using inertia of fluid to be pumped F04F)
- F15C: FLUID-CIRCUIT ELEMENTS PREDOMINANTLY USED FOR COMPUTING OR CONTROL PURPOSES (transducers F15B5/00, {F15B21/00}; fluid dynamics in general F15D; computer comprising fluid elements G06D, G06G; {electric control by means of electro-hydraulic or electro-pneumatic amplifiers G05B7/02})
- F16K: VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING {(devices for emptying and evacuating the excess liquid in valves or conduits F16L55/07)}
- G05D: SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## 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

### Claim 1

A micromachined filter comprising a substrate, a non-porous membrane, and a filter element means for removing particles of at least a predetermined size from an unfiltered fluid from an unfiltered fluid source; wherein at least a portion of said filter element means is located between said substrate and said non-porous membrane; wherein said substrate comprises a mounting portion; wherein said non-porous membrane comprises a mounting portion; wherein said substrate,'s and said non-porous membrane's mounting portions are secured together; wherein said micromachined filter further comprises an inlet port means for receiving said unfiltered fluid from said unfiltered fluid source, and for conveying said unfiltered fluid to said filter element means; and wherein said micromachined filter further comprises an outlet port means for conveying a filtered fluid from said filter element means and for permitting said filtered fluid to exit from said micromachined filter.

### Claim 2 (depends on 1)

The micromachined filter according to claim 1, wherein said substrate's and said non-porous membrane's mounting portions are anodically bonded to each other.

### Claim 3 (depends on 1)

The micromachined filter according to claim 1, wherein at least one of said non-porous membrane and said substrate comprises at least one exposed portion which is exposed to at least one of said unfiltered fluid and said filtered fluid during operation of said micromachined filter; wherein said micromachined filter further comprises a corrosion-resistant layer on at least part of said at least one exposed portion; and wherein said corrosion-resistant layer is anodically bonded to said at least one exposed portion.

### Claim 4 (depends on 3)

The micromachined filter according to claim 3, wherein said corrosion-resistant layer comprises an oxide of a transition metal selected from the group consisting essentially of titanium and zirconium.

### Claim 5 (depends on 3)

The micromachined filter according to claim 3, wherein at least part of said corrosion-resistant layer is located in a location selected to enable said corrosion-resistant layer to serve the dual functions of: (a) helping to prevent corrosion of at least part of said at least one exposed portion, and of (b) helping to prevent at least one part of said substrate from being accidentally anodically bonded to a corresponding respective part of said non-porous membrane.

### Claim 6 (depends on 3)

The micromachined filter according to claim 3, wherein said corrosion-resistant layer comprises an oxide of a transition metal.

### Claim 7 (depends on 1)

The micromachined filter according to claim 1, wherein said filter element means comprises an array of filter slots micromachined into said substrate.

### Claim 8 (depends on 7)

The micromachined filter according to claim 7, wherein said array of filter slots form an at least substantially closed figure.

### Claim 9 (depends on 8)

The micromachined filter according to claim 8, wherein said inlet port means comprises an inlet cavity for distributing said unfiltered fluid to said array of filter slots; wherein said inlet cavity at least substantially surrounds said array of filter slots; wherein said outlet port means comprises an outlet cavity for collecting said filtered fluid from said array of filter slots; and wherein said array of filter slots at least substantially surrounds said outlet cavity.

### Claim 10 (depends on 1)

The micromachined filter according to claim 1, wherein said filter element means comprises a slab filter element; wherein said inlet port means comprises an inlet port in said non-porous membrane; wherein said outlet port means comprises an outlet cavity in said substrate; and wherein, during operation of said micromachined filter, said unfiltered fluid flows from said non-porous membrane's inlet port to said slab filter element, and wherein said filtered fluid flows from said slab filter element to said substrate's outlet cavity.

### Claim 11 (depends on 10)

The micromachined filter according to claim 10, wherein at least a portion of said slab filter element is located between said non-porous membrane's inlet port and said substrate's outlet cavity.

### Claim 12 (depends on 11)

The micromachined filter according to claim 11, wherein at least one of said substrate and said non-porous membrane further comprises a filter element entrance means for permitting said slab filter element to be inserted between said non-porous membrane's inlet port and said substrate's outlet cavity.

### Claim 13 (depends on 10)

The micromachined filter according to claim 10, wherein said slab filter element comprises an exposed filter element area which is exposed to said unfiltered fluid; wherein said non-porous membrane's inlet port has an area which is at least about equal to said exposed filter element area; and wherein said substrate's outlet cavity has an area which is at least about equal to said exposed filter element area.

### Claim 14

A micromachined filter comprising a substrate, a non-porous membrane, and a slab filter element for removing particles of at least a predetermined size from an unfiltered fluid from an unfiltered fluid source; wherein said substrate comprises a mounting portion; wherein said non-porous membrane comprises a mounting portion; wherein said substrate's and said non-porous membrane's mounting portions are secured together; wherein said micromachined filter further comprises an inlet port means for receiving said unfiltered fluid from said unfiltered fluid source; wherein said micromachined filter further comprises an outlet port means for conveying a filtered fluid from said slab filter element and for permitting said filtered fluid to exit from said micromachined filter; wherein said inlet port means comprises said slab filter element; wherein said outlet port means comprises an outlet port in said non-porous membrane and an outlet cavity in said substrate; wherein at least a portion of said non-porous membrane is located between said slab filter element and said substrate; and wherein, during operation of said micromachined filter, said filtered fluid flows sequentially from said slab filter element, through said non-porous membrane's outlet port, and through said substrate's outlet cavity.