MEMS-based bubble pressure sensor for prosthetic socket interface pressure measurement

Abstract

The ability to chronically monitor pressure at the prosthetic socket/residual limb interface could provide important data to the research and clinical communities. With this application in mind, we describe a novel type of sensor which consists of a MEMS pressure sensor and custom electronics packaged in a fluid-filled bubble. The sensor is characterized and compared to two commercially-available technologies. The bubble sensor has excellent drift performance and good sensing resolution. It exhibits hysteresis which may be due to the silicone that the sensor is molded in. To reduce hysteresis, it may be advisable to place the sensor between the liner and the socket rather molding directly into the liner.

Static and cyclic performance evaluation of sensors for human interface pressure measurement

“…These commercial sensors are being evaluated against novel sensors developed at Sandia National Laboratories. The bubble sensor [5] is a Sandia developed MEMS-based diaphragm pressure sensors encapsulated in a fluid-filled bubble about 16x9x5 mm in size. Pressure on the external surface of the bubble is transduced to internal fluid pressure which is measured by the MEMS diaphragm sensor containing piezoresistive traces.…”

Examination of the Performance Characteristics of Velostat as an In-Socket Pressure Sensor

“…Attempts to produce sensors capable of measuring the pressure within prosthetic sockets have tended to involve piezoresistive [21][22][23], piezoelectric [24][25][26], capacitive [27][28][29][30], optical sensors [31][32][33][34][35][36][37] and microelectromechanical (MEMs) sensors [38][39][40][41].…”

“…MEMs sensors have been applied to lower limb prosthetics by a handful of researchers either as bespoke units [38,40] or through use of commercially available designs [39]. MEMs devices offer compact [38], low-cost [41] solutions to stress measurement.…”

“…MEMs devices offer compact [38], low-cost [41] solutions to stress measurement. Typically, these sensors exhibit high linearity [38], good drift characteristics [39] and are largely unaffected by noise [41]. Sensors may be arranged to measure both normal and shear forces [38,40,41].…”

“…Sensors may be arranged to measure both normal and shear forces [38,40,41]. However, issues with hysteresis have been noted [38,39] and limited application has been presented to clinical scenarios [40].…”