Stretchable electronic circuit

• US 8,907,376 B2
• Filed: 11/08/2012
• Issued: 12/09/2014
• Est. Priority Date: 03/20/2009
• Status: Expired due to Fees

• Current Assignee: University of Utah Research Foundation (State of Utah)
• Original Assignee: University of Utah Research Foundation (State of Utah)
• Inventors: Mascaro, Stephen, Mascaro, Debra, Abu-Khalaf, Jumana, Park, Jungwoo
• Primary Examiner(s): Pham, Thanh V
• Application Number:
  US13/672,362
• Publication Number:
  US 20140012106A1
• Time in Patent Office: 761 Days
• Field of Search: 257/177, 257/181, 257/688, 257/689, 257/226, 257/424, 257/427, 257/470, 257/E23.065, 257/E23.177
• US Class Current: 257/181
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/0295 using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: B29C 45/14639 for obtaining an insulating effect, e.g. for electrical components
• CPC Class Codes: H05K 1/0283 Stretchable printed circuits
• CPC Class Codes: H05K 1/183 Components mounted in and supported by recessed areas of the printed circuit board
• CPC Class Codes: H05K 2201/0133 Elastomeric or compliant polymer elastomeric conductor H05K2201/0314
• CPC Class Codes: H05K 2201/10106 Light emitting diode [LED]
• CPC Class Codes: H05K 2201/10121 Optical component, e.g. opto-electronic component
• CPC Class Codes: H05K 2201/10151 Sensor
• CPC Class Codes: H05K 2201/1034 Edge terminals, i.e. separate pieces of metal attached to the edge of the PCB tab H05K2201/0397
• CPC Class Codes: H05K 2201/2072 Anchoring, i.e. one structure gripping into another providing micro- or nanometer scale roughness on a metal surface H05K2203/0307
• CPC Class Codes: H05K 2203/0271 Mechanical force other than pressure, e.g. shearing or pulling
• CPC Class Codes: H05K 2203/128 Molten metals, e.g. casting thereof, or melting by heating and excluding molten solder spraying droplets of molten metal H05K2203/1344
• CPC Class Codes: H05K 2203/1327 Moulding over PCB locally or completely applying non-metallic protective coatings for encapsulating mounted components H05K3/284
• CPC Class Codes: H05K 3/143 Masks therefor H05K3/048 takes precedence
• CPC Class Codes: H05K 3/284 for encapsulating mounted components H05K1/185 takes precedence
• CPC Class Codes: H05K 3/3463 Solder compositions in relation to features of the printed circuit board or the mounting process

Abstract

A stretchable electronic circuit that includes a stretchable base substrate having a plurality of stretchable conductors formed onto a surface thereof, with both the stretchable base substrate and conductors being bendable together about two orthogonal axes. The stretchable circuit also includes a stretchable sensor layer attached to the base substrate with a cavity formed therein which has a contact point exposing one of the plurality of stretchable conductors. The stretchable electronic circuit further includes a surface mount device (SMD) package with a conductor contact protrusion installed into the cavity, and wherein a substantially constant electrical connection is established between the conductor contact protrusion and the stretchable conductor at the contact point by tensile forces interacting between the stretchable base substrate and the stretchable sensor layer.

Claims

1. A stretchable electronic circuit, comprising:

a stretchable base substrate having a plurality of stretchable conductors formed onto a surface thereof;

both the base substrate and conductors being bendable together about at least two orthogonal axes;

a stretchable sensor layer attached to the base substrate and having a surface mount device (SMD) cavity formed therein, the SMD cavity including at least one contact point exposing at least one of the plurality of stretchable conductors; and

an SMD package having a conductor contact protrusion installed into the SMD cavity, wherein tensile forces interacting between the stretchable base substrate and the stretchable sensor layer maintain a substantially constant electrical connection between the conductor contact protrusion and the stretchable conductor at the contact point.

2. The electronic circuit of claim 1, wherein the stretchable base substrate and stretchable sensor layer further comprise a biocompatible material.

3. The electronic circuit of claim 2, wherein the biocompatible material is a stretchable PDMS material.

4. The electronic circuit of claim 1, wherein the SMD package is selected from a group consisting of a light-emitting diode (LED) and a photodiode detector.

5. The electronic circuit of claim 1, further comprising:

a stretchable connector layer attached to the base substrate and having a connector well formed therein and adjacent to at least one of the plurality of stretchable conductors;

an external interface lead wire having one end installed with the connector well;

flowable conductive material filling the connector well and establishing a substantially constant electrical connection between the lead wire and the stretchable conductor; and

a stretchable cap layer over the connector well securing the lead wire to the stretchable electronic circuit and sealing the flowable conductive material within the connector well.

6. The electronic circuit of claim 5, wherein the lead wire includes an anchor to inhibit removal from the connector well.

7. The electronic circuit of claim 5, wherein the flowable conductive material is a liquid metal.

8. The electronic circuit of claim 7, wherein the liquid metal is at least one of EGaIn, GaInSn and Indalloy 60®

.

9. The electronic circuit of claim 5, wherein the flowable conductive material is a conductive polymer.

10. The electronic circuit of claim 5, wherein the SMD package further comprises a plurality of light-emitting diodes and photodiode detectors arrayed together, each diode and detector being connected through a connector well to an external interface lead wire and form a sensor system attachable to a curved surface of a human body.

11. The electronic circuit of claim 10, wherein the sensor system is configured to monitor a function of the human body selected from the group consisting of fingernail blood flow and perfusion, pulse-oximetry, photodynamic therapy and combinations thereof.

12. The electronic circuit of claim 1, wherein the plurality of stretchable conductors have a buckled non-strained configuration and a stretched configuration.

13. The electronic circuit of claim 1, wherein the sensor system is configured to monitor fingernail blood flow and perfusion using photoplethysmorgraphy.