the support for example strongly fixed weakly pinned and the membrane material properties for example elastic modulus poisson ratio density both the membrane 50 and conductive layer 36 are electrodes which develop a capacitance c between them which depends upon the electrical permittivity of the ambient material e the electrode spacing d and the electrode area a for the case where both electrodes are circular disks c e a d the sensor is then calibrated for measured capacitance versus applied pressure fig4 7 9 11 12 14 16 17 19 21 22 and 23 show the main lithographic etching and deposition steps involved in the fabrication of a pressure sensor according to the invention the masks associated with the successive steps are shown in fig3 8 10 13 15 18 and 20 when etching photoresistive material the solid black areas of the masks are the regions that are removed by the subsequent etch however when etching metal and other non photoresistive layers the blank or unmasked areas of the mask denote the regions that are removed skilled workers in this field will understand which masks are applied to photoresist and which are applied to non photoresist fig4 is section a a u2032 through the wafer 32 of a partially fabricated sensor the silicon wafer 32 has previously been ground to the required thickness and cmos circuitry 34 is deposited on its top.