Foam pressure sensor

• US 10,378,983 B2
• Filed: 07/13/2015
• Issued: 08/13/2019
• Est. Priority Date: 07/14/2014
• Status: Active Grant

• Current Assignee: Rogers Corporation (Rogers Communications Inc.)
• Original Assignee: Rogers Corporation (Rogers Communications Inc.)
• Inventors: Shere, Aniruddha, Sprentall, Karl E.
• Primary Examiner(s): Allen, Andre J
• Application Number:
  US15/326,148
• Publication Number:
  US 20170199095A1
• Time in Patent Office: 1,492 Days
• Field of Search: 73700-756
• CPC Class Codes: G01L 9/0005 using variations in capacitance G01L9/0072 takes precedence
• CPC Class Codes: G01L 9/12 by making use of variations in capacitance , i.e. electric circuits therefor

Abstract

A pressure sensor includes a first plate (102), a second plate (104) and a foam (106) disposed between the first and second plate. The foam is a polyurethane foam having an average cell size of about 50 to 250 urn and a density of between 5 to 30 lbs/ft3.

Claims

1. A hybrid sensor comprising:

a first plate;

a second plate;

a foam disposed between the first and second plate;

wherein the first plate, the second plate and the foam are disposed relative to each other forming a foam capacitor;

a conductor clad piezoelectric film is disposed on a surface of one of the first or second plates forming a piezoelectric sensor;

wherein the piezoelectric sensor has a bandwidth, defined by an intrinsic RC time constant of the piezoelectric sensor, that is larger than a bandwidth of the foam capacitor, providing a hybrid sensor having a high bandwidth impact sensor via the piezoelectric sensor, and a lower bandwidth pressure sensor via the foam capacitor.

2. The hybrid sensor of claim 1, wherein the foam has a density between 6 to 25 lbs/ft³.

3. The hybrid sensor of claim 1, wherein the foam has a compression set of less than about 10%.

4. The hybrid sensor of claim 1, wherein the foam has a force-deflection of between about 1-9 psi (7-63 kPa).

5. The hybrid sensor of claim 1, wherein the plates are metallic.

6. The hybrid sensor of claim 1, wherein the foam is a polyurethane foam having an average cell size of about 50 to 250 μ

m and a density of between 5 to 30 lbs/ft³.

7. The hybrid sensor of claim 1, wherein the first plate, the second plate, and the foam, form a foam capacitor, and wherein the foam capacitor and the conductor clad piezoelectric film are electrically connected to provide a common ground between them.

8. The hybrid sensor of claim 7, wherein the conductor clad piezoelectric film is connected between an analog to digital converter and the common ground.

9. The hybrid sensor of claim 7, wherein the foam capacitor is connected between a capacitance sensor and the common ground.