Integrated circuit-integrated flexible shear-stress sensor skin and method of fabricating the same

• US 6,825,539 B2
• Filed: 03/31/2003
• Issued: 11/30/2004
• Est. Priority Date: 04/01/2002
• Status: Expired due to Fees

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Tai, Yu-Chong, Xu, Yong
• Primary Examiner(s): TSAI, H JEY
• Application Number:
  US10/403,732
• Publication Number:
  US 20030199116A1
• Time in Patent Office: 610 Days
• Field of Search: 257/414-420
• US Class Current: 257/417
• CPC Class Codes: A61B 2562/028 Microscale sensors, e.g. electromechanical sensors [MEMS]
• CPC Class Codes: A61B 2562/164 the sensor is mounted in or on a conformable substrate or carrier
• CPC Class Codes: B81C 1/00246 Monolithic integration, i.e. micromechanical structure and electronic processing unit are integrated on the same substrate
• CPC Class Codes: B81C 2203/0735 Post-CMOS, i.e. forming the micromechanical structure after the CMOS circuit
• CPC Class Codes: G01L 9/0055 bonded on a diaphragm
• CPC Class Codes: G01M 9/065 dealing with flow

Abstract

An IC-integrated, flexible, shear-stress sensor skin is made by providing a wafer with integrated circuits and sensor elements which are fabricated in the wafer, disposing a first polymer layer on the wafer and sensor elements to provide mechanical support for the sensor elements, defining a cavity below the sensor elements to provide thermal isolation, while the sensor element remains supported by the first polymer layer, and isolating the sensor elements into a plurality of islands defined in the wafer, so that the islands, with at least one sensor element on at least one of the islands, and the integrated circuits form the IC-integrated, flexible, shear-stress sensor skin. The invention is an IC-integrated, flexible, sensor skin made according to the method.

Claims

1. A monolithic IC-integrated, flexible, shear-stress sensor skin comprising:

a flexible supporting skin;

a wafer defined into a plurality of islands carried by the flexible supporting skin;

at least one integrated circuit fabricated in or on the wafer carried by the flexible supporting skin;

an integrated electrical coupling connected to the integrated circuit;

at least one integrated sensor element fabricated in or on each island during the same fabrication process as the integrated circuit, carried by the flexible supporting skin and coupled to the integrated circuit through the integrated electrical coupling;

a first polymer layer disposed on the wafer and on the sensor element, the first polymer layer providing mechanical support for the sensor element and islands; and

a cavity defined in the island below each sensor element to provide thermal isolation from the island, while the sensor element remains supported by the first polymer layer,

whereby the islands, each with at least one sensor element, and the integrated circuit coupled thereto form the IC-integrated, flexible, shear-stress sensor skin.

2. The sensor of claim 1 where the first polymer layer comprises two polymer layers forming a compound layer, wherein at least one of the two layers is chosen of a material suited for use with the sensor elements.

3. The sensor of claim 2 where the two polymers layers comprise a first of the two polymer layers to form a mechanical support for the islands and a second of the two polymer layers to form a diaphragm support for the sensor elements.

4. The sensor of claim 3 where a first of the two polymer layers and a second of the two polymer layers comprises a Parylene C layer as the first of the two polymer layers forming a mechanical support for the islands and a Parylene N layer as the second of the two polymer layers forming a diaphragm support for the sensor elements.

5. The sensor of claim 1 where the first polymer layer is disposed on a first side of the wafer and further comprising a second polymer layer on an opposing second side of the wafer to encapsulate the islands between the first and second polymer layers.

6. The sensor of claim 1 where the plurality of islands defined in the wafer are defined by deep reactive ion etching regions of the wafer containing at least one sensor element.

9. The sensor of claim 4 where the second polymer layer comprises a Parylene C layer disposed as the second polymer layer on the opposing side.

7. An IC-integrated, flexible, shear-stress sensor skin comprising:

a wafer defined into a plurality of islands;

at least one integrated circuit fabricated in or on the wafer;

at least one sensor element fabricated in or on each island and coupled to the integrated circuit;

a polymer layer disposed on the wafer and on the sensor element, the polymer layer providing mechanical support for the sensor element and islands; and

a cavity defined in the island below each sensor element to provide thermal isolation from the island, while the sensor element remains supported by the polymer layer,

where the integrated circuits comprise biasing or signal conditioning circuits adapted for the sensor elements among the integrated circuits provided in the wafer.

8. The sensor of claim 7 where the integrated circuit comprises a multiplexer for selectively accessing a plurality of the sensor elements on the skin.

10. A monolithic IC-integrated, flexible sensor skin comprising:

a flexible supporting skin;

a wafer defined into a plurality of islands and carried by the flexible supporting skin;

at least one integrated circuit fabricated in or on the wafer carried by the flexible supporting skin;

an integrated electrical coupling connected to the integrated circuit;

at least one integrated sensor element fabricated in or on at least one island during the same fabrication process as the integrated circuit, carried by the flexible supporting skin, and coupled to the integrated circuit through the integrated electrical coupling;

whereby the islands with at least one sensor element, and the integrated circuit coupled thereto form the IC-integrated, flexible sensor skin.

11. The IC-integrated, flexible sensor skin of claim 10 where the integrated circuit includes at least one gate and where the sensor element is fabricated in an integrated process with the gate of the integrated circuit.

12. The IC-integrated, flexible sensor skin of claim 10 where the skin is placed into contact with biological tissue and where the sensor element and integrated circuit in combination monitors a physiological parameter.