High-sensitivity self-feedback type alarm circuit for gas sensor

A gas sensor and alarm circuit technology, applied in the electronic field, can solve the problem of not having self-feedback function and so on

Active Publication Date: 2016-07-13
INST OF PROCESS ENG CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the load resistors or gas sensors in the above technologies are both electronic components at both ends, and do not have self-feedback function.
Although there is also a patent application for connecting the three-terminal electronic component of the field effect transistor in series with the gas sensor (CN204697045U), its function is to facilitate the adjustment of the transistor resistance and stabilize the voltage division of the circuit so that the resistance value of the gas sensor can be read digitally. No obvious self-feedback feature

Method used

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  • High-sensitivity self-feedback type alarm circuit for gas sensor
  • High-sensitivity self-feedback type alarm circuit for gas sensor
  • High-sensitivity self-feedback type alarm circuit for gas sensor

Examples

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Effect test

example 1

[0024] Example 1, n-type oxide semiconductor SnO 2 The gas sensor is connected in series with the p-type field effect transistor, and one end of the sensor is connected to the positive pole of the test voltage V DD , the source of the transistor is grounded, the gate is short-circuited to the drain, and the voltage across the transistor is taken as the output voltage, such as image 3 shown. When the sensor encounters alcohol, its resistance decreases, causing the current in the circuit to rise and the voltage on the drain of the transistor to increase. At the same time, since the gate and drain of the transistor are short-circuited, the gate voltage and the drain voltage increase synchronously, resulting in a decrease in the current in the p-type transistor. The reduction of the current in the series circuit further leads to a decrease in the voltage division on the sensor, and an increase in the voltage division on the transistor, which is the self-feedback effect. Throug...

example 2

[0025] Example 2, p-type oxide semiconductor Cu 2 O The gas sensor is connected in series with the p-type field effect transistor, and one end of the sensor is connected to the positive pole of the test voltage V DD , the source of the transistor is grounded, the gate is short-circuited to the drain, and the voltage across the sensor is taken as the output voltage, such as Figure 4 shown. When the sensor encounters hydrogen, its resistance increases, causing the current in the circuit to decrease and the voltage between the source and drain of the transistor to decrease. At the same time, since the gate and drain of the transistor are short-circuited, the gate voltage decreases synchronously with the drain voltage, resulting in an increase in the current in the p-type transistor. The increase of the current in the series circuit further leads to the increase of the partial voltage on the sensor, which is the self-feedback effect. Through continuous self-feedback adjustment...

example 3

[0026] Example 3, p-type oxide semiconductor LaFeO 3 The gas sensor is connected in series with the n-type field effect transistor, and the drain of the transistor is connected to the positive pole of the test voltage V DD , the other end of the sensor is grounded, and the gate passes through a fixed series resistor R 0 Short-circuit the source, take the divided voltage of the sensor as the output voltage, such as Figure 5 shown. When the sensor encounters formaldehyde, its resistance increases, causing the current in the circuit to decrease and the voltage between the source and drain of the transistor to decrease. At the same time, since the gate and source of the transistor are short-circuited through a fixed resistor, the decrease in current leads to an increase in the gate voltage, which eventually leads to an increase in the current in the n-type transistor. The increase of the current in the series circuit further leads to the increase of the partial voltage on the ...

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Abstract

The invention discloses a high-sensitivity self-feedback type alarm circuit for a gas sensor, and belongs to the electronic fields of gas sensors, alarms and the like.A gas-sensitive resistor of the semiconductor gas sensor and a source electrode and a drain electrode of a field effect transistor are serially connected with one another to form the high-sensitivity self-feedback type alarm circuit, and a grid electrode of the field effect transistor and the source electrode or the drain electrode are connected with each other by a series resistor or without the series resistor according to the polarity of the field effect transistor and the polarity of the semiconductor gas sensor to form a self-feedback circuit.The high-sensitivity self-feedback type alarm circuit is powered by direct-current test voltages, and increased divided voltages of the gas sensor and the field transistor or increased divided voltages of the field effect transistor and series resistor are used as alarm voltages to be outputted.The sensor works at the room temperature, or resistance wires are heated by the aid of a heating power source, so that the sensor can work at specific temperatures.The high-sensitivity self-feedback type alarm circuit has the advantages that the high-sensitivity self-feedback type alarm circuit has an obvious self-feedback characteristic as compared with the traditional gas sensor and fixed load resistor series connection mode, and the sensitivity of the high-sensitivity self-feedback type alarm circuit can be greatly improved.

Description

technical field [0001] A high-sensitivity self-feedback gas sensor alarm circuit belongs to the electronic fields of gas sensors and alarms. Background technique [0002] Semiconductor gas sensors have important applications in the detection and alarm of flammable and explosive gases, toxic and harmful gases, air pollution gases, and food hygiene-related gases. Its working principle is that at a certain temperature, the resistance of the semiconductor material changes with the concentration of the gas to be measured. Such as figure 1 As shown, the change of the resistance of the gas sensor will cause the change of the current in the circuit, and through the series connection with the load resistance, it will eventually lead to the change of the load resistance or the partial pressure on the gas sensor. The change of this partial pressure can drive an external circuit to alarm or display the concentration information of the gas to be measured through digital-to-analog conve...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N27/12G08B21/16
CPCG01N27/12G08B21/16G01N33/0063G08B21/14
Inventor 韩宁武晓峰陈运法
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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