Description

The sensor structure consists of an integrated heater located within a thin electrical and thermal insulating membrane. Two thin film resistors are used for heating and measuring the temperature of the membrane. Two resistors are integrated on the silicon beside the membrane for the compensation off the ambient temperature changes.

Features

• Stable long term operation
• Physical method for gas concentration measurement
• Low power consumption
• Small dimensions

Operating Principle

The thermal conductivity sensor measures the concentration of a specific gas between a hot surface resistor and an ambient temperature reference resistor using the thermal conductivity coefficient of the gas itself. Gases which have a lower density than air (CH4) cause a decrease on the surface membrane temperature. On the other hand, gases with densities heavier than air (CO2) increase the temperature of the measuring resistor.​​