Supersensitive linear pressure transducer

• US 9,408,555 B2
• Filed: 06/30/2011
• Issued: 08/09/2016
• Est. Priority Date: 06/30/2010
• Status: Active Grant

• Current Assignee: Indiana University Research & Technology Corporation (Indiana University), Purdue Research Foundation (The Trustees of Purdue University (d/b/a Purdue University))
• Original Assignee: Indiana University Research & Technology Corporation (Indiana University), Purdue Research Foundation (The Trustees of Purdue University (d/b/a Purdue University))
• Inventors: Akingba, A. George, Clark, Jason V.
• Primary Examiner(s): Fitzgerald, John
• Assistant Examiner(s): Roberts, Herbert K
• Application Number:
  US13/807,431
• Publication Number:
  US 20130109990A1
• Time in Patent Office: 1,867 Days
• US Class Current: 1/1
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 2562/028 Microscale sensors, e.g. electromechanical sensors [MEMS]
• CPC Class Codes: A61B 5/03 Detecting, measuring or recording fluid pressure within the body other than blood pressure, e.g. cerebral pressure; Measuring pressure in body tissues or organs A61B5/205 takes precedence
• CPC Class Codes: A61B 5/08 Detecting, measuring or recording devices for evaluating the respiratory organs A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/113 occurring during breathing
• CPC Class Codes: A61B 5/6846 specially adapted to be brought in contact with an internal body part, i.e. invasive
• CPC Class Codes: A61B 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• CPC Class Codes: A61B 5/6867 specially adapted to be attached or implanted in a specific body part A61B5/6847 takes precedence
• CPC Class Codes: A61M 2016/0021 with a proportional output signal, e.g. from a thermistor
• CPC Class Codes: A61M 2016/0027 pressure meter
• CPC Class Codes: A61M 2205/04 implanted
• CPC Class Codes: A61M 2205/3317 Electromagnetic, inductive or dielectric measuring means
• CPC Class Codes: A61M 2205/332 Force measuring means
• CPC Class Codes: G01L 9/0072 using variations in capacitance
• CPC Class Codes: H04R 19/00 Electrostatic transducers
• CPC Class Codes: H04R 2201/003 Mems transducers or their use of the electrostatic type H04R19/005

Abstract

Apparatus and methods for a MEMS-fabricated variable capacitor. In one embodiment the capacitor is a comb drive comprising a plurality of plates interdigitated with a corresponding blades. As the plates move relative to the blades, the capacitance of the sensor changes. The capacitor is sufficiently sensitive to measure respiratory pressure in an animal.

Claims

1. A microfabricated variable capacitor, comprising:

a stator including a plurality of electrically conductive plates each spaced apart from one another, each said pair of adjacent plates forming a channel between, each of said plates being in a first common electrical communication;

a rotor including a plurality of electrically conductive blades, said rotor being suspended relative to said stator such that each of said blades is received within a corresponding one of said channels and each said blade includes an area that overlaps with an area of an adjacent said plate, each of said blades being in a second common electrical communication;

a flexible diaphragm; and

a suspension system for flexibly coupling said rotor and said diaphragm, said system configured and adapted to apply a load from the diaphragm to the stator in one direction and unable to substantially apply a load from the diaphragm to the stator in another direction;

wherein the capacitance between the first electrical communication and the second electrical communication varies in correspondence to the overlapping areas between each said blade and an adjacent plate.

2. The capacitor of claim 1 wherein said suspension system couples to said rotor such that no net torque is exerted on the suspension system by the rotor.

3. The capacitor of claim 1 wherein said plates are planar and said blades are planar.

4. The capacitor of claim 1 wherein said plates are circular about an axis and said blades are circular about the same axis.

5. The capacitor of claim 1 wherein said rotor includes a centrally located hub, and said blades are cantileveredly supported from said hub.

6. The capacitor of claim 5 which further comprises a cantilever arm supporting said blades, one end of said arm being coupled to said hub, each said blade extending from said arm in a direction transverse to the direction from the hub to the other end of said arm.