Silicon Pressure Sensor for in Situ Pressure Measurement in a Pressurized Superfluid Helium Environment

A silicon piezo-resistive pressure sensor is investigated for possible in situ pressure measurement in a pressurized superfluid helium environment. A small pressure sensor, PD116, from Toyoda Machine Works Ltd, has been reported as an applicable sensor for in situ pressure measurement up to the maximum pressure of 3 MPa at cryogenic temperatures down to 6 K. It has a low temperature coefficient of sensitivity around 200 ppm/K between 300 and 6 K. In order to evaluate the applicability in a pressurized superfluid helium environment, the PD116 sensor was set in a specific cryostat which can provide superfluid helium environment. The characteristics of the sensor were measured for the pressure range from 100 kPa to 170 kPa at 4.2 K and 2.0 K. A driving current of 1 mA was applied to the sensor in order to limit heat dissipation to less than 1 mW. The pressure dependence of the output voltage of the sensor also indicates high linearity at temperatures lower than 4.2 K. The experimental results of this study clearly indicate a possible use of this sensor for in situ pressure measurement in a pressurized superfluid helium environment.