PH meter and sensor thereof

Abstract

A pH sensor is disclosed, including conductive glass, a SnO2 film formed on the conductive glass, and a field effect transistor (FET) with a gate coupled to the SnO2 film. When the SnO2 film contacts a liquid with a predetermined voltage, voltage between the liquid and the SnO2 film varies according to pH of the liquid, thereby changing channel current of the FET. The pH of the liquid can thus be determined according to the channel current.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

FIG. 1 is an architectural diagram of a chemical sensing platform in accordance with an embodiment of the invention;

FIG. 2 is a schematic diagram of a sensing and amplification device in accordance with an embodiment of the invention; and

FIG. 3 shows response relation of a sensing and amplification of FIG. 2 with temperature of a liquid.

Claims

1. A pH sensor, comprising: conductive glass;a SnO2 film formed on the conductive glass; anda field effect transistor with a gate coupled to the SnO2 film;wherein the SnO2 film contacts a liquid with a predetermined voltage to generate a voltage difference therebetween, the pH sensor determining pH of the liquid according to a linear relationship between channel current of the field effect transistor and the voltage difference.

2. The pH sensor of claim 1, further comprising a conductive wire with one end connecting the SnO2 film and the other end connecting the gate of the field effect transistor; with the field effect transistor connected to the SnO2 film via the conductive wire without immersion in the liquid.

3. The pH sensor of claim 2, further comprising an insulating material covering the conductive glass and the conductive wire, exposing the SnO2 to contact the liquid.

4. A chemical sensing platform for detecting pH of a liquid, comprising: a reference electrode in the liquid, providing a stable voltage; andat least one pH sensor, comprising: conductive glass;a SnO2 film formed on the conductive glass; anda field effect transistor with a gate coupled to the SnO2 film;wherein the SnO2 film contacts a liquid with a predetermined voltage to generate a voltage difference between the liquid and the SnO2 film, the pH sensor determining pH of the liquid according to a linear relationship between channel current of the field effect transistor and the voltage difference.

5. The chemical platform of claim 4, wherein the pH sensor further comprises a conductive wire with one end connecting the SnO2 film and the other end connecting the gate of the field effect transistor; with the field effect transistor connected to the SnO2 film via the conductive wire without immersion in the liquid.

6. The chemical platform of claim 5, wherein the pH sensor further comprises an insulating material covering the conductive glass and the conductive wire, exposing the SnO2 to contact the liquid.

7. The chemical platform of claim 4, further comprising a light-isolating device to accommodate the liquid and prevent influence of light on measurement.

8. The chemical platform of claim 4, further comprising a temperature control system to maintain environmental temperature.

9. The chemical platform of claim 8, wherein the temperature control system comprises: a temperature detection device measuring the measuring environment temperature; anda heating/cooling device adjusting the environmental temperature to a desired temperature.

10. The chemical platform of claim 4, wherein the reference electrode is a Ag/AgCl reference electrode.

11. The chemical platform of claim 4, wherein the field effect transistor is a field effect transistor of an input of an operational amplifier.

12. The chemical platform of claim 4, further obtaining a linear relationship between pH of more than two liquids of standard pH and output voltages of the operational amplifier at a fixed temperature, before calculating the pH of a liquid according to output voltage of the operational amplifier at the fixed temperature when the SnO2 film contacts the liquid.

13. The chemical platform of claim 4, further comprising a push-button interface for users to set measurement parameters.

14. The chemical platform of claim 4, further comprising a remote control interface for users to set measurement parameters.

15. The chemical platform of claim 4, further comprising a display interface to display the measurement results.