E. Kalvesten et al., SMALL PIEZORESISTIVE SILICON MICROPHONES SPECIALLY DESIGNED FOR THE CHARACTERIZATION OF TURBULENT GAS-FLOWS, Sensors and actuators. A, Physical, 46(1-3), 1995, pp. 151-155
Piezoresistive microphones have been designed and fabricated using sur
face micromachining technology. The acoustic sensors, which are specia
lty designed for turbulent gas flow measurements, are fabricated with
the very small diaphragm side lengths of 100 and 300 mu m. An expressi
on for the dynamic pressure sensitivity is derived where the diaphragm
bending forces, the tensile built-in strain forces, as well as the fl
uid compressibility forces are considered. The acoustic sensitivities,
which are in the range 0.3-0.9 mu V/Pa for a supply voltage of 10 V,
are compared with the calculated values, showing good agreement. The f
requency response is flat up to 10 kHz within +/-2 dB. The ability to
measure the smallest pressure eddies in a turbulent boundary layer is
verified and compared for different diaphragm sizes.