A CMOS-compatible temperature sensor based on the gaseous thermal conduction dependent on temperature

There are many different types of temperature sensors, including thermal resistor, thermocouple, thermal diode, etc. All the operational principles of them are based on the fact that some property of the sensor material is temperature-related. Based on the fact that the gaseous thermal conductivity of air is linear to the temperature from 250 K to 500 K, this paper proposes a new type of temperature sensor which employs the gas between the microhotplate and its substrate as the temperature sensing component. The temperature sensor consists of the CMOS-compatible tungsten microhotplate fabricated by surface micromachining technology as the heating component, the gas between the microhotplate and the substrate as the sensory material and the constant current circuit as the bias circuit. The heat of microhotplate can be dissipated by the gaseous thermal conduction which is dependent on the gas temperature. The measurement results show that the sensitivity of the sensor is 1 mV/°C and its linearity is 1.48% from −20 °C to 70 °C. The sensor with the inflatable sealed package with N2 or inert gas can immerge in the gas or liquid atmosphere to measure the temperature.