Stretchable two-dimensional pressure sensor

• US 8,316,719 B2
• Filed: 11/12/2010
• Issued: 11/27/2012
• Est. Priority Date: 11/12/2010
• Status: Active Grant

• Current Assignee: President and Fellows of Harvard College (Harvard Corporation)
• Original Assignee: President and Fellows of Harvard College (Harvard Corporation)
• Inventors: Wood, Robert J., Majidi, Carmel S., Bérard, Phillippe, Park, Yong-Lae
• Primary Examiner(s): ALLEN, ANDRE J
• Application Number:
  US12/945,014
• Publication Number:
  US 20120118066A1
• Time in Patent Office: 746 Days
• Field of Search: 73700-756
• US Class Current: 73/719
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 5/11 Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb for measuring pulse A61B5/02 ;A61B5/1038 takes precedence; motion detection to correct for motion artifacts in physiological signals A61B5/721
• CPC Class Codes: A61B 5/6892 Mats
• CPC Class Codes: G01L 1/02 by hydraulic or pneumatic means
• CPC Class Codes: G01L 1/205 using distributed sensing elements

Abstract

A pressure sensor for measuring the location and intensity of an applied pressure, including an elastomeric sheet; and a plurality of micro-channels embedded in the elastomeric sheet.

Claims

1. A pressure sensor for measuring the location and intensity of an applied pressure, comprising:

an elastomeric sheet; and

a plurality of micro-channels embedded in said elastomeric sheet;

wherein said micro-channels are filled with an electrically conductive material.

2. The pressure sensor of claim 1, wherein said micro-channels comprise two orthogonal sets of rows.

3. The pressure sensor of claim 1, wherein said elastomeric sheet is an elastic material with an elastic modulus of 10-1000 kiloPascals.

4. The pressure sensor of claim 1, wherein each of said micro-channels has a width greater than or equal to a depth.

5. The pressure sensor of claim 4, wherein said width and said depth are each between 1 and 1000 microns in length.

6. The pressure sensor of claim 5, wherein said micro-channels comprise two orthogonal sets of rows with a spacing between parallel rows in each set, and

wherein said spacing is between 1 micron and 10 millimeters.

7. A method of fabricating a pressure sensor comprising:

forming an elastomeric sheet having a plurality of micro-channels embedded therein; and

filling said micro-channels with a conductive material.

8. The method of claim 7, wherein said forming step comprises:

casting an elastomeric material in each of three molds to form a flat elastomeric sheet and two micro-channeled elastomeric sheets;

bonding the flat elastomeric sheet and the two micro-channeled elastomeric sheets.

9. The method of claim 8, wherein said filling step occurs between said casting step and said bonding step.

10. The method of claim 8, wherein said filling step occurs after said forming step.

11. A method of determining a location of pressure applied to a pressure sensor, comprising:

measuring at a first time the electric resistance of a conductive fluid filling each of a plurality of channels embedded in said pressure sensor;

measuring at a second time the electric resistance of said conductive fluid filling each of said plurality of channels embedded in said pressure sensor;

identifying the channels having the greatest change in electric resistance.

12. A method of determining an intensity of pressure applied to a pressure sensor, comprising:

measuring at a first time the electric resistance of a conductive fluid filling each of a plurality of channels embedded in said pressure sensor;

measuring at a second time the electric resistance of said conductive fluid filling each of said plurality of channels embedded in said pressure sensor;

determining a relative change in the electrical resistance of each of said channels.

13. A pressure sensor capable of indicating intensity and location of an applied pressure, comprising:

an elastomeric sheet defining a two dimensional surface;

a first plurality of micro-channels, embedded in said elastomeric sheet, extending along the two dimensional surface and a second plurality of micro-channels, embedded in said elastomeric sheet, extending along the two dimensional surface transverse to but not intersecting the first plurality of micro-channels;

an electrically conductive liquid filling at least one of the first plurality of micro-channels and at least one of the second plurality of micro-channels; and

wherein the first plurality of micro-channels do not intersect with the second plurality of micro-channels and the electrically conductive fluid filling at least one of the first plurality of micro-channels does not come in contact with the electrically conductive fluid filling at least one of the second plurality of micro-channels.

14. A pressure sensor according to claim 13 wherein a pressure applied to the two dimensional surface causes at least one of the first plurality of micro-channels and the second plurality of micro-channels to change in shape and cause a conductive liquid in the micro-channel to change in resistance.