| Popis: |
The report describes the construction, testing and calibration of piezoelectric polymer sensing transducers of two sizes. The piezoelectric material was obtained by poling 25 micrometer thick, polyvinylidene fluoride sheet. Sensors with an active area of 1 cm diameter, intended for dynamic interface-pressure measurements, were calibrated in a fixture generating normal pressure transients by means of piston impact. Sensors with an active area of 2 mm diameter, intended for measuring dynamic pressures while implanted in the cranium of rhesus monkeys, were calibrated in an oil cell with a piston-cylinder seal which provided hydraulic pressure transients by means of impact on the piston. The larger sensors had a normal-pressure sensitivity around 3 microvolts/Pa (20 mV/psi) and the smaller sensors a hydraulic-pressure sensitivity around 0.7 microvolts/Pa (5 mV/psi). |
