To provide a micro mechanical vacuum sensor for determining the pressure within a cavity of a micro mechanical element.

The sensor includes a substrate 2, at least one electrically conductive support member 4 connected to the substrate, and a thermally resistive layer 1 supported by the at least one support member 3 and spaced from the substrate by the support member to provide a space between the thermally resistive layer and the substrate. The sensor is configured such that the thermally resistive layer is substantially thermally insulated from the substrate. The sensor is further configured to be driven such that the pressure within the cavity is determined by a temperature value detected by the sensor.