Pressure or gas sensor and sensing method using nano-cavities

摘要

The pressure or gas composition sensor is based on measuring the heat flow through a thermal conductor (7). The thermal conductor (7) has a solid matrix that forms a plurality of cavities. The average extension of the cavities is less than 100 nm. This is based on the understanding that the free path length of the gas molecules at pressures around 1 bar is in the order of 100 nm (or somewhat lower). Hence, the cavities show a strong pressure or composition dependence of the thermal conductivity around 1 bar, which makes the sensor suited for measurements in this pressure regime. To carry out a measurement, a temperature gradient is generated in the matrix for inducing a heat flux. A parameter depending on the heat flux is measured and used to derive the pressure or composition.