OPTICAL SENSOR FOR MEASURING A FORCE DISTRIBUTION

• US 20100253650A1
• Filed: 09/09/2008
• Published: 10/07/2010
• Est. Priority Date: 09/10/2007
• Status: Active Grant

• Current Assignee: Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno
• Original Assignee: Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno
• Inventors: Schoo, Harmannus Franciscus Maria, Dietzel, Andreas Heinrich, Koetse, Marinus Marc
• Granted Patent: US 8,749,522 B2
• Time in Patent Office: Days
• US Class Current: 345/175
• CPC Class Codes: G01L 1/241 by photoelastic stress analysis
• CPC Class Codes: G01L 1/247 using distributed sensing elements, e.g. microcapsules along a single optical fibre G01L1/242

Abstract

According to one aspect, the invention provides an optical sensor for measuring a force distribution, comprising a substrate; one or more light emitting sources and one or more detectors provided on the substrate, the detectors responsive to the light emitted by the sources; wherein a deformable opto-mechanical layer is provided on said substrate with light responsive properties depending on a deformation of the opto-mechanical layer.

The design of the sensor and particularly the use of optical components in a deformable layer make it possible to measure the contact force accurately. The sensor is scalable and adaptable to complex shapes. In one embodiment also a direction of the contact force can be determined.

Claims

1. An optical sensor for measuring a force distribution, comprising:

a substrate;

one or more light emitting sources and one or more light receiving detectors provided on the substrate, the detectors being responsive to the light emitted by the sources;

characterized in that a deformable opto-mechanical layer is provided on said substrate with light responsive properties depending on a deformation of the opto-mechanical layer.

2. A sensor according to claim 1, wherein the light emitting sources are organic light emitting diodes (OLED'"'"'s) or polymer light emitting diodes (PLED'"'"'s).

3. A sensor according to claim 1, wherein the light receiving detectors are organic photo diodes (OPD'"'"'s) or polymer photo diodes (PPD'"'"'s).

4. A sensor according to claim 1, wherein the light emitting sources and light receiving detectors are provided on the substrate by means of physical vapor deposition.

5. A sensor according to claim 1, wherein the light comprises various wavelengths.

6. A sensor according to claim 1, wherein the opto-mechanical layer comprises optical cavities;

each optical cavity spanning one or more light emitting sources and one or more light receiving detectors;

the light responsive properties within an optical cavity depend on the deformation of the optical cavity.

7. A sensor according to claim 1, wherein the light emitting sources are provided with lenses to focus the emitted light, whereby the detectors are arranged to detect the focused light.

8. A sensor according to claim 1, wherein the walls of the cavities are provided with a light reflecting pattern, whereby the detectors are arranged to detect the light pattern.

9. A sensor according to claim 8, wherein the non-reflective parts of the walls of the optical cavities possess light absorbing properties, thus preventing optical crosstalk.

10. A sensor according to claim 1, wherein protrusions are attached to the opto-mechanical layer;

each cavity connected to one or more protrusions;

the protrusions adjusted in size and shape to transfer a directional force to a cavity deformation.

11. A sensor according to claim 1, wherein the opto-mechanical layer comprises PDMS (polydimethylsiloxane).

12. A sensor according to claim 1 where the opto-mechanical layer comprises a deformable Bragg reflector.

13. A flow sensor comprising a sensor according to claim 10, wherein the protrusions are provided on the surface of the sensor;

to be contacted with a fluid, transferring the movement of the fluid to the opto-mechanical layer.

14. A sensor according to claim 1, wherein the substrate is of a flexible or stretchable nature.

15. A sensor according to claim 14, wherein the substrate comprises polyethylenes or polyimides.

16. An acoustic sensor comprising a fluid sensor according to claim 13.

17. A smart skin comprising a sensor according to claim 1.

18. A touch screen comprising a sensor according to claim 1.

19. A device comprising an array of sensors according to claim 1.