Pressure sensor calibration using a water-filled latex finger to account for the mechanical interaction between the hard palate and the deformable human tongue.

Abstract

We present a calibration system called Dried Water Column (DWC). It applies pressure on a sensor with a latex finger filled with water, which pressure is controlled with a water column. This is intended to mimic the way the deformable tongue mechanically interacts with the hard palate. We show that, once some specificities of the elastic/plastic behavior of the latex finger are taken into account, namely the softening due to Mullins Effect and the non-elastic deformation occurring above a certain pressure level, the DWC provides a reliable measure of the linear relation between the pressure and the output voltage of the sensor within the limited pressure range [0, 2.5kPa]. Such a precise calibration would not be possible with a rigid actuator, which position on the sensor can dramatically influence the measures. Extrapolating the linear relationship thus determined to a larger pressure range compatible with speech production and swallowing ([0, 35kPa]), is possible once it has been verified that the behavior of the sensor is linear over this pressure range. This can be done with any rigid or semi rigid actuator. This reliable calibration procedure can be easily reproduced in any laboratory, and can be applied to any pressure sensor.