One-electrode semiconductor sensors for detection of toxic and explosive gases in air

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Sensors and Actuators B, 7 ( 1992) 505-506

One-electrode semiconductor explosive gases in air S. N. Malchenko,

I. N. Lychkovsky

sens.ors for detection of toxic and

and M. V. Baykov

Byelorussian State University, Minsk (Byelorussia)

Abstract The construction and characteristics of one-electrode semiconductor gas sensors developed by the authors are presented. The sensors are shown to have a high sensitivity to noxious and inflammable gases, high performance reliability, stability and low response time. The main advantages of this kind of sensor are low power consumption and a small deviation of the initial parameters.

Semiconductor gas sensors of the resistor type are widely used in devices designed for the detection and monitoring of noxious and inflammable gases in air. The paper deals with one-electrode semiconductor sensors (OESS) with a Pt spiral, which acts as both a heater and a measuring electrode [ 1,2]. The sensor function is based on shunting of the heater resulting from the interaction of a metal oxide semiconductor and detected gas molecules. Results and discussion (W

Figure 1 shows the construction of the sensor (a) and the general appearance of the sensitive elements (b). This type of sensor is characterized by a low power consumption (less than 0.15 W). OESS are highly sensitive to the gases to be detected (Fig. 2), reliable, have a small response time (not more than 3 s) and a small deviation of the initial resistance ( < 10%). Individual or complex semiconductor oxides of the elements belonging to groups III, IV and V of the Periodic Table can be used as the gas-sensitive material. The sensor sensitivity and selectivity for the gas to be detected can be controlled to a considerable extent by modifying

Fig. 1. (a) Construction of the sensor: 1, protective porous cap; 2, housing; 3, racks; 4, current pick-off contacts; 5, sensitive element; 6, platinum wire. (b) SEM micrograph of the sensitive element of a one-electrode semiconductor sensor.

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Fig. 2. Output

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@ 1992 -

Elsevier

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the semiconductor with different additives ( Sb203, Fe203, Bit03, AlzOg, CdO, Pd, Ag, Pt, etc.). It has been established that OESS can be used in mobile and stationary indicators and gas analysers for detecting and localizing the escape of combustible and noxious gases over a wide range of concentrations.

reliability, stability and a low response time. The main advantages of the OESS are low power consumption and a small deviation of the initial parameters.

References Conclusions

Our investigation showed that OESS have a high sensitivity to the analysed gases, performance

1 New Cosmos Electric Co. Ltd., Gas sensor, EP N 0115953(1984). 2 S.V. Baran, S. N. Malachenko, G. A. Branitsky et al., Method for the production of the sensitive element, USSR SU N 1445393 (1986).