Dual-function active matrix sensor array

Patent metadata

Field	Value
Publication number	US-9949683-B2
Application number	US-201514977910-A
Country	US
Kind code	B2
Filing date	Dec 22, 2015
Priority date	Dec 22, 2015
Publication date	Apr 24, 2018
Grant date	Apr 24, 2018

Abstract

A method is provided for making multiple environmental measurements using a single sensing element. Each sensing element (sensel) includes a thin-film transistor (TFT) and a passive element. Typically, a plurality of sensels is provided arranged into an array. In response to an electrical stimulus, an electrical measurement is supplied that is responsive to a change in TFT electrical characteristic correlated to a first environmental condition, as well as a change in a characteristic of the passive element correlated to a second environmental condition. When the sensels are formed in an array, a plurality of electrical measurements is supplied corresponding plurality of locations on a monitored surface. Some exemplary environmental conditions include temperature, pressure, moisture, chemicals, oxygen, solution pH, salinity, and shear. The method determines the first environmental condition independent of the second environmental condition, while determining the second environmental condition independent of the first environmental condition.

First claim

I claim:

1. A dual-function active matrix sensor array comprising:
a substrate with a top surface;
a plurality of sensing elements (sensels) formed in an array overlying the substrate top surface, each sensel comprising:
a thin-film transistor (TFT) having a channel resistance or source-to-drain resistance (R DS ) responsive to a first environmental condition;
a passive element having an AC impedance responsive to a second environmental condition, different than the first environment condition; and,

a measurement device selectively connectable to each sensel in the array to simultaneously determine first environmental condition measurements and second environmental condition measurements, wherein:
the measurement device supplies an AC signal having a predetermined first amplitude and predetermined first phase, and makes a first environmental condition determination and a second environmental condition determination in response to detecting a change in the AC signal amplitude with respect to the AC signal first amplitude, and a change in AC signal phase with respect to the AC signal first phase.

2. The sensor array of claim 1 further comprising:
a DC voltage source;
a gate driver switching network to selectively connect a gate electrode of each sensel TFT to the DC voltage source.

3. The sensor array of claim 2 further comprising:
a data driver switching array to selectively connect a drain electrode or source electrode of each sensel TFT to the measurement device, simultaneous with the gate driver switching network connecting the gate of the corresponding TFT to the DC voltage source.

4. The sensor array of claim 1 wherein the passive element is selected from the group consisting of a capacitor, parallel-plate, co-planar interdigitated electrode, metal-oxide-semiconductor (MOS) capacitor, and an inductor.

5. The sensor array of claim 1 wherein the first and second environmental conditions are selected from a group consisting of temperature, pressure, moisture, chemicals, oxygen, solution pH, salinity, and shear.

6. The sensor array of claim 1 wherein the measurement device has a user output to supply a map of first and second environmental conditions, cross-referenced to sensel locations in the array.

7. The sensor array of claim 1 wherein the measurement device detects a first AC signal amplitude change and a first AC signal phase change and determines the first environmental conditions independent of second environmental condition measurements, and determines the second environmental conditions independent of first environmental condition measurements.

8. The sensor array of claim 1 wherein each sensel TFT R DS is responsive to temperature as the first environmental condition.

9. The sensor array of claim 1 wherein each sensel TFT comprising a gate dielectric sensitive to a moisture first environmental condition, with the R DS responsive to changes in the moisture content of the gate dielectric.

10. The sensor array of claim 1 wherein the passive element is a capacitor comprising a dielectric sensitive to a second environmental condition selected from the group consisting of pressure, moisture, chemicals, solution pH, oxygen, salinity, and shear, with a capacitance responsive to the second environmental condition.

11. The sensor array of claim 1 wherein each sensel TFT comprising a gate dielectric sensitive to a force or pressure first environmental condition, with the R DS responsive to changes in the force or pressure applied upon the gate dielectric region of the TFT.

12. The sensor array of claim 1 wherein the measurement device supplies an AC signal at a plurality of frequencies, each AC signal frequency having a predetermined amplitude and phase, and makes a first environmental condition determination and a second environmental condition determination in response to detecting a change in the plurality of AC signals.

13. A method for making multiple environmental measurements using a single sensing element, the method comprising:
providing a sensing element (sensel) including a thin-film transistor (TFT) and a passive element, the sensel TFT having a gate electrode, a drain electrode, and a source electrode;
accepting a first electrical stimulus, wherein accepting the first electrical stimulus includes:
accepting a DC voltage at the gate electrode of the sensel TFT; and,
simultaneously accepting an AC signal at the drain electrode or source electrode of the sensel TFT;

in response to the first electrical stimulus, supplying a first electrical measurement responsive to:
a change in TFT electrical characteristic correlated to a first environmental condition; and,
a change in a characteristic of the passive element correlated to a second environmental condition.

14. The method of claim 13 wherein accepting the AC signal include accepting an AC signal with a first amplitude and a first phase; and,
wherein supplying the first electrical measurement includes supplying the AC signal with a second amplitude, different than the first amplitude, and a second phase, different than the first phase.

15. The method of claim 14 wherein accepting the AC signal includes accepting a plurality of AC signals at different frequencies, each AC signal frequency having a predetermined amplitude and predetermined phase.

16. The method of claim 13 wherein supplying the first electrical measurement includes supplying the first electrical measurement in response first and second environmental conditions selected from a group consisting of temperature, pressure, moisture, chemicals, oxygen, solution pH, salinity, and shear.

17. The method of claim 13 further comprising:
in response to supplying the first electrical measurement, determining the first environmental condition independent of the second environmental condition; and,
in response to supplying the first electrical measurement, determining the second environmental condition independent of the first environmental condition.

18. The method of claim 13 wherein supplying the first electrical measurement in response to the TFT characteristics includes the TFT characteristics being channel resistance or source-to-drain resistance (R DS ).

19. The method of claim 18 wherein the TFT R DS is responsive to temperature as the first environmental condition.

20. The method of claim 18 wherein providing the sensel includes providing a TFT with a gate dielectric sensitive to a moisture first environmental condition, with the R DS responsive to changes in the moisture content of the gate dielectric.

21. The method of claim 13 wherein providing the sensel passive element includes providing a sensel with a capacitor having a dielectric sensitive to a second environmental condition selected from the group consisting of pressure, moisture, chemicals, solution pH, oxygen, salinity, and shear, with a capacitance responsive to the second environmental condition.

22. The method of claim 13 wherein providing the sensel includes providing a TFT comprising a gate dielectric sensitive to a force or pressure first environmental condition, with the R DS responsive to changes in the force or pressure applied upon the gate dielectric region of the TFT.

23. The method of claim 13 wherein providing the sensel including the TFT and a passive element includes providing a plurality of sensels arranged in an addressable array;
the method further comprising:
arranging the array of sensels over a surface; and

Assignees

• Sharp Laboratories Of America Sla Inc
• Sharp Laboratories America Inc

Inventors

• Afentakis Themistokles

Classifications

• A61B2562/0247

  Pressure sensors · CPC title

• A61B2562/029

  Humidity sensors · CPC title

• A61B2562/0261

  Strain gauges · CPC title

• A61B5/447 Primary

  specially adapted for aiding the prevention of ulcer or pressure sore development, i.e. before the ulcer or sore has developed · CPC title

• A61B5/6892

  Mats · CPC title