STRETCHABLE IONICS FOR TRANSPARENT SENSORS AND ACTUATORS

• US 20160025669A1
• Filed: 04/10/2014
• Published: 01/28/2016
• Est. Priority Date: 04/10/2013
• Status: Active Grant

• Current Assignee: President and Fellows of Harvard College (Harvard Corporation)
• Original Assignee: President and Fellows of Harvard College (Harvard Corporation)
• Inventors: SUO, Zhigang, WHITESIDES, George M., SUN, Jeong Yun, KEPLINGER, Christoph Matthias
• Granted Patent: US 10,302,586 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01N 27/02 by investigating impedance
• CPC Class Codes: G01N 27/305 optically transparent or photoresponsive electrodes
• CPC Class Codes: G01N 27/3335 the membrane containing at least one organic component G01N27/3271 takes precedence; aspects concerning the enzyme reagent in enzyme electrodes C12Q1/001
• CPC Class Codes: H01G 9/022 Electrolytes; Absorbents

Abstract

A class of devices enabled by ionic conductors is highly stretchable, fully transparent to light of all colors, biocompatible or biodegradable, and capable of operation at frequencies beyond 10 kilohertz and voltages above 10 kilovolts. These devices enabled by ionic conductors can be used as large strain actuators, full-range loudspeakers, as strain or pressure sensors and as stretchable interconnects. The electromechanical transduction is achieved without electrochemical reaction. When large stretchability and high optical transmittance are required, the ionic conductors have lower sheet resistance than all existing electronic conductors.

Claims

1. An electrode comprising:

an ionic electrode;

at least an external signal and

a dielectric layer,

wherein the ionic electrode is capacitively coupled with the external signal by the dielectric layer.

2. The electrode of claim 1, further comprising an ionic electrolyte;

wherein the ionic electrolyte comprises an elastomer or electroactive polymer and an electrolyte dispersed throughout the elastomer or electroactive polymer to provide a transparent electrolyte.

3. The electrode of claim 2, wherein the electrolyte layer elastomer comprises a hydrogel or a lyogel.

4. The electrode of claim 1, wherein the electrolyte comprises an aqueous salt solution.

5. The electrode of claim 4, wherein aqueous salt solution comprises a deliquescent salt.

6. The electrode of claim 4, wherein the aqueous salt solution has a salt concentration in the range of fully saturated to isotonic in physiological systems such as cells.

7. The electrode of claim 1, wherein the electrolyte comprises an ionic liquid.

8. The electrode of claim 7, wherein the ionic liquid forms a liquid layer.

9. The electrode of claim 8, wherein the liquid layer is confined within boundaries to prevent flow.

10. The electrode of claim 7, wherein an elastomer is swollen with the ionic liquid to provide an elastomeric ionic electrode.

11. The electrode of claim 1, wherein the electrolyte further comprises a humectant.

12. The electrode of claim 1, wherein electrolyte solution has a minimum resistivity of 0.02 Ohm-meter.

13. The electrode of claim 1, wherein the electrolyte has a transmittance of greater than 95%.

14. The electrode of claim 1, further comprising electrical connectors in electrical contact with the transparent electrolyte for connection to an electronic circuit.

15. The electrode of claim 1, wherein the dielectric is transparent.

16. The electrode of claim 15, wherein the dielectric is an elastomer.

17. The electrode of claim 15, wherein the dielectric is biodegradable or biocompatible.

18. The electrode of claim 15, wherein the dielectric is an electroactive polymer, such as a piezoelectric polymer.

19. The electrode of claim 1, wherein the electrode is stretchable.

20. The electrode of claim 1, wherein the electrode is biodegradable or biocompatible.

21. The electrode of claim 1, wherein the transparent electrode is encapsulated to reduce loss of electrolyte.

22. The electrode of claim 1, wherein the electrode is configured as a stretchable wire or interconnect for use in circuits.

23. A transparent transducer, comprising:

a dielectric layer comprising an elastomer;

a plurality of transparent electrolyte layers disposed on opposing faces of the dielectric layer, wherein the electrolyte layer comprises an elastomer and an electrolyte dispersed throughout the elastomer; and

at least an electrical connector in electrical contact with the transparent electrolyte layers.

24. The transparent transducer of claim 23, wherein the electrical connectors are for connection to a voltage source.

25. The transparent transducer of claim 23, wherein the electrolyte layer elastomer comprises a hydrogel or a lyogel.

26. The transparent transducer of claim 23, wherein the electrolyte comprises an aqueous salt solution.

27. The transparent transducer of claim 26, wherein aqueous salt solution comprises a deliquescent salt.

28. The transparent transducer of claim 26, wherein the aqueous salt solution has a salt concentration in the range of fully saturated to isotonic in physiological systems such as cells.

29. The transparent transducer of claim 23, wherein the electrolyte comprises an ionic liquid.

30. The transparent transducer of claim 23, wherein the electrolyte further comprises a humectant.

31. The transparent transducer of claim 23, wherein electrolyte solution has a minimum resistivity of 0.02 Ohm-meter.

32. The transparent transducer of claim 23, wherein the transparent electrolyte has a transmittance of greater than 95%.

33. The transparent transducer of claim 23, wherein the boundary of the transparent transducer is constrained.

34. The transparent transducer of claim 23, wherein the boundary of the dielectric layer is unconstrained.

35. The transparent transducer of claim 23, wherein the transducer comprises a plurality of dielectric layers, each dielectric layer having a plurality of transparent electrolyte layers disposed on opposing faces of the dielectric layers.

36. The transparent transducer of any one of claim 35, wherein the dielectric layer and electrolyte layers are patterned.

37. The transparent transducer of claim 23, further comprising upper and lower layers that serve as vapor barriers.

38. The transparent transducer of claim 23, wherein the transducer operates at a frequency of up to 20 kHz, or 20 Hz to 20 kHz, or 20 kHz to 1 MHz, or 1 MHz to 100 MHz, or 100 MHz to 1 GHz and/or 1 GHz to 10 GHz.

39. The transparent transducer of claim 23, wherein the transduced is configured for use as a loudspeaker.

40. A transparent sensor comprising:

the transducer of claim 23; and

wherein the electrical connectors on the electrolyte layers are configured for electrical connection to a capacitance meter.

41. The transparent sensor of claim 40, wherein the sensor is configured for use as a strain sensor.

42. The transparent sensor of claim 40, wherein the sensor is configured for use as a pressure sensor.

43. A transparent sensor according to claim 40, wherein a plurality of sensors are arranged in an array.

44. A transparent sensing screen, comprising a plurality of sensors according to claim 40 arranged in an array or other pattern, said screen afixable to a surface for providing information regarding location and/or pressure on the surface.

45. A method of measuring a mechanical stimulus comprising:

providing a sensor according to claim 40; and

recording a capacitance, wherein the capacitance correlates to a mechanical stimulus applied to the sensor.

46. The method of claim 45, wherein the mechanical stimulus is strain.

47. The method of claim 45, wherein the mechanical stimulus is pressure.