Objective:

This paper presents the development and manufacture of a gas microsensor whose operation is based on variations in electrical conductivity in the presence of certain gases. To use these sensors in portable equipment such as gas monitors, the power used to keep the film sensitive to the operating temperature is required to be very low. The results of this development provide with a platform for the manufacture of gas microsensors that allow different types of sensor films can be incorporated.

Methodology:

The developed microsensor consists of a thin fil of SnO2 deposited on a micro-machined silicon substrate. The proposed design was carried out by simulations of mechanical and thermal behavior. The procedure included microfabrication operations, and then, the electrical characterization was performed and the sensitivity to gaseous ammonia was tested.

Results:

Microfabrication was carried out satisfactorily (although this work does not detail all the steps of the process), and a high rate of well-formed sensors per sheet was achieved. The behavior of the sensor in the presence of different concentrations of gaseous ammonia in air was characterized and resulted in a linear response for concentrations between 6 ppm to 50 ppm, and the latter is the permissible limit of exposure.

Conclusions:

A low consumption (50 mW) SnO2 gas microsensor was successfully developed based on previous simulations. In relation to future work, the developed micromachined platform with the built-in heater will allow the use of different sensor films.