袖珍式数字PH计

Pocket-size Digital Acidimeter

本文分析了新颖化学敏感半导体传感器——Si_3N_4绝缘栅场效应管,对H^+离子的敏感机理。提出了袖珍式数字酸度计的设计原则和方法,并对进一步改进PH传感器进行了讨论。

Ion_sensitive Field_Effect Transistor (ISFET) is a new integr- ated device. This device functions as an ion_sensitive transducer. It is the fr- uit of the combination of the technology of the semiconductor and electrical chemistry. Further more, ISFET' S have Potential advantages over conventional ion selctive electrodes in their rapid response, small size, and low output im- pedance. This ISFET is smilar to the conventional MOSFET except that the metal gate electrode is removed in order that the gate insulator can play the role of an ion selective electrod. It is sensitive to various kinds of ions, such as H^+, K^+ and Na^+ etc. The magnitude of pH value is determined by the densith of H ion. The report presented here will give a detailed analysis of the principle of how Si_3N_4 insulator gate TSFET senses H^+ ion. Also, the full explation is given in this report of how to use the Chinese_built CMOS LSI CH7106 de- vice and other devices to make up proket_size 3(1/2) digit LCD acidimeter. As to the measuring principle of the circuit and its typical usage, the report will provide you with the detailed information, Moreover, the discussion about how to further improve the sensors, to increase its precision and to simplify the ciruit,also can be found in this paper. Comparing this ISFET with the conventional pH glass electrdes acidimeter on the market,you would find the digital acidimeter has got a lot of merits. And its advantages are as follows: small in size(including a small sensor); pleasant to the eye; simple in construction; conveient in use, quick to respo- nse; reliable in measuring.