Magnetic stimulus of isfet-based sensor to enable trimming and self-compensation of sensor measurement errors

Patent metadata

Field	Value
Publication number	US-2016349209-A1
Application number	US-201615233392-A
Country	US
Kind code	A1
Filing date	Aug 10, 2016
Priority date	Mar 27, 2014
Publication date	Dec 1, 2016
Grant date	—

Abstract

An ion sensor apparatus comprises at least one ion sensitive field effect transistor (ISFET) device configured to be exposed to a liquid, a reference electrode configured to contact the liquid to which the ISFET device is exposed, and at least one magnet configured to intermittently expose the ISFET device to a magnetic field. A processor is operatively connected to the ISFET device and the reference electrode. The processor modulates the magnetic field to produce a corresponding modulated output in resistance of the ISFET device, and modulation of a reported output value of the ion sensor apparatus.

First claim

What is claimed is:

1 . An ion sensor apparatus, comprising
at least one ion sensitive field effect transistor (ISFET) device configured to be exposed to a liquid; a reference electrode configured to contact the liquid to which the ISFET device is exposed; at least one magnet configured to intermittently expose the ISFET device to a magnetic field; and a processor operatively connected to the ISFET device and the reference electrode; wherein the processor modulates the magnetic field to produce a corresponding modulated output in resistance of the ISFET device, and modulation of a reported output value of the ion sensor apparatus.

2 . The sensor apparatus of claim 1 , wherein the at least one magnet comprises an electromagnet.

3 . The sensor apparatus of claim 2 , wherein the electromagnet is selectively activated by the processor to intermittently expose the ISFET device to the magnetic field produced by the electromagnet.

4 . The sensor apparatus of claim 1 , wherein the at least one magnet comprises a permanent magnet.

5 . The sensor apparatus of claim 4 , further comprising a magnetic shield that is configured to intermittently expose the ISFET device to the magnetic field produced by the permanent magnet.

6 . The sensor apparatus of claim 1 , further comprising a magnetic field sensor adjacent to the magnet and configured to measure the magnitude or state of the magnetic field.

7 . The sensor apparatus of claim 1 , further comprising a counter electrode configured to contact the liquid to which the ISFET device is exposed, wherein the processor is operatively connected to the counter electrode.

8 . The sensor apparatus of claim 1 , further comprising at least one temperature sensor and a pressure sensor, wherein the temperature sensor and the pressure sensor are configured to contact the liquid to which the ISFET device is exposed.

9 . The sensor apparatus of claim 1 , further comprising a flow tube configured to receive the liquid, wherein the ISFET device is disposed within the flow tube.

10 . The sensor apparatus of claim 9 , further comprising a flow valve that controls the flow of the liquid into the flow tube.

11 . The sensor apparatus of claim 1 , wherein the ISFET device comprises:
a semiconductor substrate having a top surface; a source and a drain located in opposing side portions of the semiconductor substrate; a pair of electrical Hall contacts each located in opposing side portions of the semiconductor substrate that are adjacent to the side portions where the source and drain are located; and a gate channel, which is sensitive to ions in the liquid, located in a top central portion of the semiconductor substrate between the source and the drain, and between the pair of electrical Hall contacts; wherein the source, the drain, and the electrical Hall contacts are separate from each other and located below the top surface of the semiconductor substrate.

12 . The sensor apparatus of claim 1 , wherein the reported output value is a pH measurement of the liquid.

13 . A semiconductor device, comprising:
a semiconductor substrate having a top surface; a plurality of contacts located in opposing side portions of the semiconductor substrate; and an ion sensitive channel located in a top central portion of the semiconductor substrate between the contacts; wherein the contacts are separate from each other and located below the top surface of the semiconductor substrate.

14 . The semiconductor device of claim 13 , further comprising one or more rotary switches that selectively couple the contacts to one or more voltage sources, such that the contacts are electrically configured for taking a pH measurement or a Hall effect potential measurement when the semiconductor device is employed in an ion sensor apparatus.

Assignees

• Honeywell Int Inc

Inventors

• Horkheimer Donald

Classifications

• G01N27/4168

  Oxidation-reduction potential, e.g. for chlorination of water (water analysis G01N33/18) · CPC title

• G01N27/4148 Primary

  Integrated circuits therefor, e.g. fabricated by CMOS processing · CPC title

• G01N27/4165

  for pH meters · CPC title

• G01N27/4167

  pH (electrodes therefor G01N27/302, G01N27/36) · CPC title

• G01N27/414 Primary

  Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS · CPC title