MINIATURE PRESSURE SENSOR ASSEMBLY

• US 20080314136A1
• Filed: 08/28/2008
• Published: 12/25/2008
• Est. Priority Date: 10/18/2004
• Status: Active Grant

• Current Assignee: Precision Mechatronics Pty Ltd
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Silverbrook, Kia, Mallinson, Samuel George
• Granted Patent: US 7,980,139 B2
• Time in Patent Office: Days
• US Class Current: 73/146.8
• CPC Class Codes: B60C 23/0408 transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver

Abstract

A miniature pressure sensor assembly is provided for fitting within the valve stem of a vehicle tire. The pressure sensor assembly typically includes a reference device for temperature compensation and a measurement device for pressure measurement. Each device includes a substrate assembly defining a plurality of holes. A deflectable membrane is mounted to the substrate assembly to define a first chamber. A cap is mounted to the membrane to form a second chamber.

Claims

1. A pressure sensor assembly for fitting within the valve stem of a vehicle tire, the assembly comprising:

a substrate assembly defining a plurality of holes;

a deflectable membrane mounted to the substrate assembly to define a first chamber; and

a cap mounted to the membrane to form a second chamber.

2. A pressure sensor assembly as claimed in claim 1, which further includes:

another deflectable membrane mounted to the substrate assembly to define a third chamber; and

another cap mounted to the other membrane to form a fourth chamber.

3. A pressure sensor assembly as claimed in claim 1, wherein the membrane defines a plurality of holes through which the first and second chambers are interconnected.

4. A pressure sensor assembly as claimed in claim 1, wherein the first chamber is a sealed chamber and the cap defines a plurality of holes so that the second chamber is an open chamber.

5. A pressure sensor assembly as claimed in claim 1, wherein the pressure sensor assembly is a Microelectromechanical system (MEMS) formed using integration circuit fabrication techniques.

6. A pressure sensor assembly as claimed in claim 5, wherein the substrate assembly includes:

a silicon substrate layer;

a CMOS layer deposited on the silicon substrate layer;

a conductive layer deposited on the CMOS layer; and

a passivation layer deposited on the conductive layer;

wherein said plurality of holes pass through each layer.

7. A pressure sensor assembly as claimed in claim 6, wherein the membrane is conductive and the conductive layer and conductive membrane together form a pair of electrodes which can develop a capacitance between them.

8. A pressure sensor assembly as claimed in claim 1, wherein the membrane is formed from non-conductive material which is in contact with piezo material.