AlxGa1-xAs semiconductor sensor for contact pressure measurement

The use of AlxGa1-xAs firm based sensors for measuring contact pressure is described. It is shown that the pressure sensors display a nearly linear dependence of resistance to contact pressure and temperature. Pressure sensitivity ranges from 0.09%/MPa to 0.12%/MPa (with a non-linearity of < 3.0%) while temperature sensitivity is about 0.2%/K to 0.4%/K (with a non-linearity of < 0.1%). The largest deviation between the loading and unloading curves is about 0.15% of no load resistance in the range 0-21 MPa. The sensors are also found to be sensitive to light. Results from creep tests showed that under constant pressure the sensors are stable with fluctuations of +/- 0.15% for a period of 300 h. (C) 2000 Published by Elsevier Science S.A. All rights reserved.