Pressure

=**Pressure Sensor**=

**Background**
The pressure sensor used for DREAMS is a Honeywell ASDX Silicon Pressure Sensor. It is an absolute pressure sensor, which means that it measures pressure relative to a perfect vacuum. It is characterized for operation from a single power supply of 5.0 Vdc. It is a capacitive pressure sensor, meaning that the sensor uses a diaphragm and pressure cavity to create a variable capacitor to detect strain due to applied pressure.

**Equation**
This is the equation given by the spec sheet for the pressure sensor: Output (volts) = ((0.8 x Vsupply)/(Pmax - Pmin)) x (Papplied - Pmin) + 0.10 x Vsupply The transfer function limits are from 10% to 90% calibration, meaning that 10% of the Vsupply correlates to the minimum pressure value, and 90% of the Vsupply correlates to the maximum pressure value. The equation derived from the data collected during testing is Pressure = (26.514 kPa/V)*Voltage -14.77 kPa.

**Data**
The data collected has a very consistent, linear pattern. The R^2 value of 0.9997 indicates that the regression line fits the data very well. The linear pattern of the data allows pressure to be easily calculated from the voltage output of the pressure sensor.