Evaluation of a sensor for low interface pressure applications.

An ultra-thin, small sensor has recently been developed, "FlexiForce" (Tekscan, Boston, MA, USA), which may be effective for the measurement of low interface pressure between the skin, support surfaces and pressure garments. To evaluate the suitability of the sensor for these applications, drift, repeatability, linearity, hysteresis and curvature effects were tested under laboratory conditions. The drift was 1.7-2.5%/logarithmic time, the repeatability was 2.3-6.6% and the linearity was 1.9-9.9% in the range of forces of 10-50 g applied. The hysteresis was 5.4% on average. The output offset of the sensor increased with decreasing radius of curvature for radii less than 32 mm compared with a flat surface when no pressure was applied. The sensitivity to pressure decreased with curvature for radii less than 32 mm. It was found that the sensor had acceptable drift, repeatability, linearity and hysteresis. However, a significant curvature effect was observed indicating that the sensor is suitable for direct measurement on surfaces with the radii greater than 32 mm under static conditions.