Micromachined fluidic apparatus

• US 6,477,901 B1
• Filed: 12/21/1999
• Issued: 11/12/2002
• Est. Priority Date: 12/21/1999
• Status: Expired due to Term

• Current Assignee: Integrated Sensing Systems Incorporated
• Original Assignee: Integrated Sensing Systems Incorporated
• Inventors: Tsai, Chialun, Tadigadapa, Srinivas, Najafi, Nader, Zhang, Yafan
• Primary Examiner(s): Fuller, Benjamin R.
• Assistant Examiner(s): THOMPSON, JEWEL VERGIE
• Application Number:
  US09/468,628
• Time in Patent Office: 1,057 Days
• Field of Search: 738/623.52, 731/182, 732/042.6, 731/94, 732/042.5, 732/042.3, 738/623.55, 738/613.56, 738/613.57, 738/610.4, 738/613.54
• US Class Current: 73/861.352
• CPC Class Codes: G01F 1/8404 details of flowmeter manufacturing methods
• CPC Class Codes: G01F 1/8445 micromachined flowmeters
• CPC Class Codes: G01F 1/8472 having curved measuring conduits, i.e. whereby the measuring conduits' curved center line lies within a plane G01F1/8481 takes precedence
• CPC Class Codes: G01N 11/16 by measuring damping effect upon oscillatory body
• CPC Class Codes: G01N 2009/006 vibrating tube, tuning fork
• CPC Class Codes: G01N 9/002 using variation of the resonant frequency of an element vibrating in contact with the material submitted to analysis G01N9/34 takes precedence
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/49428 Gas and water specific plumbing component making
• CPC Class Codes: Y10T 29/49995 Shaping one-piece blank by removing material

Abstract

Micromachine fluidic apparatus incorporates a free-standing tube section and electrodes to actuate or control the movement of the tube section, or to sense the movement of the tube section, or both. Electronic circuitry, which may be disposed on the same substrate as the fluidic portion of the apparatus, is used in conjunction with the tube and electrodes in conjunction with a variety of different applications, including fluid flow measurement, fluid density measurement, fluid viscosity measurement, fluid transport, separation and/or mixing. According to a particular embodiment, the free-standing section of the tube is resonated for fluid flow and density measurements according to the Coriolis effect. Capacitive/electrostatic actuation techniques are used to control or resonate the free-standing section of the tube, and to detect variations in tube movement. Different methods of fabricating micromachine fluidic apparatus are also disclosed, including the use of fusion bonding of non-conducting substrates, high-aspect ratio etching techniques, and anisotropic etching and refill techniques, preferably utilizing chevron-shaped slit openings to fabricate microtube sections.

Claims

1. Micromachined fluidic apparatus, comprising:

a substrate;

a micromachined tube on or within the substrate, the tube comprising a fluid inlet, a fluid outlet, and a free-standing portion between the fluid inlet and fluid outlet the free-standing portion being spaced apart from the substrate and separated from the substrate by a gap;

means for vibrating the free-standing portion of the tube as a fluid flows through the tube from the fluid inlet to the fluid outlet; and

means for sensing movement of the free-standing portion of the tube.

2. The micromachined fluidic apparatus of claim 1, wherein the vibrating means comprises:

a first electrode defined on the free-standing portion of the tube;

a second electrode defined on the substrate in opposed, facing relation to the first electrode; and

electronic circuitry interconnected to the first and second electrodes.

3. The micromachined fluidic apparatus of claim 1, wherein the sensing means comprises:

a first electrode defined on the free-standing portion of the tube;

a second electrode defined on the substrate in opposed, facing relation to the first electrode; and

electronic circuitry interconnected to the first and second electrodes.

4. The micromachined fluidic apparatus of claim 1, further comprising an electrically insulating between the tube and the substrate.

5. The micromachined fluidic apparatus of claim 4, wherein the electrically insulating layer is silicon dioxide or silicon nitride.

6. The micromachined fluidic apparatus of claim 1, wherein the tube is attached to the substrate using anodic bonding, fusion bonding, eutectic bonding, thermal bonding, glass-frit bonding, compression bonding, thermal-compression bonding, or a combination thereof.

7. The micromachined fluidic apparatus of claim 1, wherein the substrate has a first surface and an oppositely-disposed second surface, the tube is disposed at the first surface, and the fluid inlet and the fluid outlet are located at at least one of the first and second surfaces.

8. The micromachined fluidic apparatus of claim 1, wherein at least portions of the vibrating means and the sensing means are supported on the substrate.

9. The micromachined fluidic apparatus of claim 1, further comprising a hermetically sealed cap bonded to the substrate so as to define a hermetically-sealed enclosure containing at least the free-standing portion of the tube.

10. The micromachined fluidic apparatus of claim 9, wherein the cap is constructed of glass, ceramic, metal, alloy, plastic, silicon, silicon including at least one insulating layer, or combinations thereof.

11. The micromachined fluidic apparatus of claim 9, wherein the hermetically-sealed cavity is evacuated.

12. The micromachined fluidic apparatus of claim 9, further comprising a getter material within the hermetically-sealed cavity, the getter material maintaining a vacuum within the hermetically-sealed cavity.

13. The micromachined fluidic apparatus of claim 1, wherein at least one of the vibrating means and the sensing means operates electrostatically or capacitively.

14. The micromachined fluidic apparatus of claim 1, further comprising means in communication with the vibrating means and the sensing means for measuring flow rate, viscosity or density of a fluid flowing through the tube.

15. The micromachined fluidic apparatus of claim 1, wherein the tube is part of a fluid switch or fluid circuit.

16. The micromachined fluidic apparatus of claim 1, wherein the vibrating means is operable to cause the free-standing portion of the tube to resonate.

17. The micromachined fluidic apparatus of claim 16, wherein the free-standing portion of the tube is resonated by an electrostatic/capacitive force, electromagnetic force, thermally based actuation force, piezoelectric force, or mechanical vibration generated by the vibrating means.

18. The micromachined fluidic apparatus of claim 1, wherein the sensing means operates using capacitive, resistive, piezoresistive, piezoelectric, magnetic, optical or tunneling techniques.

19. The micromachined fluidic apparatus of claim 1, wherein the vibrating means and the sensing means cooperate to measure fluid mass flow based upon the Coriolis effect, fluid density, or both.

20. The micromachined fluidic apparatus of claim 19, wherein:

the free-standing portion of the tube comprises first and second corner portions and a midportion therebetween;

the vibrating means comprises an actuation electrode on the midportion;

the sensing means comprises sensing electrodes located at the corner portions; and

the sensing electrodes are operable to detect twisting of the free-standing portion of the tube as a result of fluid flow through the tube in conjunction with the Coriolis effect.

21. The micromachined fluidic apparatus of claim 1, wherein the tube is a first tube in a fluid circuit that comprising at least a second micromachined tube connected in series with the first tube, the second micromachined tube comprising a fluid inlet, a fluid outlet, and a free-standing portion between the fluid inlet and fluid outlet.

22. A micromachined fluidic apparatus comprising:

a substrate;

a micromachined tube supported by the substrate, the tube comprising a fluid inlet, a fluid outlet, and a free-standing portion between the fluid inlet and fluid outlet, the free-standing portion being spaced apart from the substrate and comprising first and second lateral portions separated by a midportion therebetween;

a first actuation electrode on the midportion and a second actuation electrode on the substrate, the first actuation electrode being separated from the second actuation electrode by a gap, the first and second actuation electrodes being operable to cause the free-standing portion of the tube to vibrate; and

first sensing electrodes on the first and second lateral portions and second sensing electrodes on the substrate, each of the first sensing electrodes being separated from a corresponding one of the second sensing electrodes by a gap, the first and second sensing electrodes being operable to detect twisting of the free-standing portion of the