Reference pH sensor, preparation and application thereof

• US 7,727,370 B2
• Filed: 03/03/2009
• Issued: 06/01/2010
• Est. Priority Date: 01/04/2006
• Status: Expired due to Fees

• Current Assignee: National Yunlin University of Science and Technology
• Original Assignee: National Yunlin University of Science and Technology
• Inventors: Tzeng, Diing-Jia, Chou, Jung-Chuan
• Primary Examiner(s): Mulpuri; Savitri
• Application Number:
  US12/397,231
• Publication Number:
  US 20090170207A1
• Time in Patent Office: 455 Days
• Field of Search: 204/433, 204/416, 204/192.17, 257/253, 257/414, 257/40, 438 48- 49, 438/99
• US Class Current: 204/433
• CPC Class Codes: G01N 27/414 Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS
• CPC Class Codes: Y10T 436/12 Condition responsive control

Abstract

A reference pH sensor, the preparation and application thereof. The reference pH sensor is an extended gate field effect transistor (EGFET) structure and comprises a metal oxide semiconductor field effect transistor (MOSFET) on a semiconductor substrate, a sensing unit comprising a substrate, a solid-state conductive sensing layer on the substrate, and a polypyrrole layer on the solid-state conductive sensing layer, and a metal wire connecting the MOSFET and the sensing unit.

Claims

1. A system of measuring pH value in a solution, comprising a first pH sensor which is an extended gate field effect transistor structure, comprising:

a first metal oxide semiconductor field effect transistor (MOSFET);

a first extended gate as a first sensing unit, comprising a first substrate, and a first solid-state conductive layer thereon; and

a first conductive wire connecting the first MOSFET and the first sensing unit.

a second pH sensor as a reference pH sensor supplying stable voltage, comprising;

a second metal oxide semiconductor field effect transistor (MOSFET);

a second extended gate as a second sensing unit, comprising a second substrate, a second solid-state conductive layer thereon, and a polypyrrole layer on the second solid-state conductive layer; and

a second conductive wire connecting the second MOSFET and the second sensing unit;

a semiconductor characteristic instrument connecting the first pH sensor and the second pH sensor respectively;

a temperature controller comprising a temperature control center, a thermocouple, and a heater, wherein the temperature control center connects the thermocouple and the heater, respectively; and

a light-isolation container isolating the sensing unit of the second pH sensor from photosensitive effect;

wherein measurement of pH value of a solution comprising;

pouring a solution into the light-isolation container;

immersing the sensing unit of the first and the second pH sensors, and the thermocouple in the solution;

adjusting temperature of the solution by the heater controlled by the temperature control center after detecting temperature variation in the solution by the thermocouple;

transmitting measurement data from the first and the second pH sensors to the semiconductor characteristic instrument; and

reading out current-voltage (I-V) values of the solution by the semiconductor characteristic instrument to obtain pH value of the solution.

2. The system as claimed in claim 1, wherein the first and the second MOSFETs are n-type.

3. The system as claimed in claim 1, wherein the first and the second substrates are silicon.

4. The system as claimed in claim 1, wherein the first and the second solid-state conductive layers are ruthenium oxide.

5. The system as claimed in claim 1, wherein the first and the second sensing units further comprises an insulating layer covered on the sensing units.

6. The system as claimed in claim 5, wherein the insulating layer is epoxy resin.

7. The system as claimed in claim 1, wherein the semiconductor characteristic instrument is Keithley 236.

8. The system as claimed in claim 1, wherein the light-isolation container is a dark box.