Sensor apparatus using an electrochemical cell

A method for sensing mechanical quantities such as force, stress, strain, pressure and acceleration is disclosed. This technology is based on a change in the electrochemically generated voltage (electromotive force) with application of force, stress, strain, pressure or acceleration. The change in the voltage is due to a change in the internal resistance of the electrochemical cell with a change in the relative position or orientation of the electrodes (anode and cathode) in the cell. The signal to be detected (e.g. force, stress, strain, pressure or acceleration) is applied to one of the electrodes to cause a change in the relative position or orientation between the electrodes. Various materials, solid, semisolid, gel, paste or liquid can be utilized as the electrolyte. The electrolyte must be an ion conductor. The examples of solid electrolytes include specific polymer conductors, polymer composites, ion conducting glasses and ceramics. The electrodes are made of conductors such as metals with dissimilar electro negativities. Significantly enhanced sensitivities, up to three orders of magnitude higher than that of comparable commercial sensors, are obtained. The materials are substantially less expensive than commercially used materials for mechanical sensors. An apparatus for sensing such mechanical quantities using materials such as doped 1,4 cis-polyisopropene and nafion. The 1,4 cis-polyisopropene may be doped with lithium perchlorate or iodine. The output voltage signal increases with an increase of the sensing area for a given stress. The device can be used as an intruder alarm, among other applications.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of the device structure of a sensor involving a solid electrolyte;

FIG. 2 is a schematic of a sensor with electrodes deposited in a side-by-side structure;

FIG. 3 is a graph of the sensor output characteristics for different magnitudes of applied forces. The configuration of this sensor is as given in FIG.

1. The output voltages were recorded on an oscilloscope and no amplifier was required. A maximum change in voltage of about 15 mV was observed for a force of about 0.8.

1. An apparatus for sensing mechanical quantities such as force, stress, strain, pressure, and acceleration, comprising:

2. The apparatus of claim 1 in which the 1,4 cis-polyisoprene is doped with lithium perchlorate.

3. The apparatus of claim 1 in which the 1,4 cis-polyisoprene is doped with iodine.

4. A method for sensing mechanical quantities such as force, stress, strain, pressure and acceleration comprising:

5. The method of claim 4 in which the electrolyte is polyethylene oxide doped with lithium perchlorate.

6. The method of claim 4 in which the electrolyte is nafion.

7. The method of claim 4 in which the electrolyte is a doped polyaniline.

8. The method of claim 4 in which the electrolyte is 1,4 cis-polyisopropene in the crosslinked form doped with lithium perchloride.

9. The method of claim 4 in which the electrolyte is 1,4 cis-polyisopropene doped with iodine.

10. A method for sensing mechanical quantities such as force, stress, strain, pressure, and acceleration comprising:

11. An apparatus for sensing mechanical quantities such as force, stress, strain, pressure, and acceleration, comprising:

12. An apparatus for sensing mechanical quantities such as force, stress, strain, pressure, and acceleration, comprising:

13. The apparatus of claim 12 wherein the sensing area of the apparatus is greater than 10 cm

2.