A contact-type piezoresistive micro-shear stress sensor for above-knee prosthesis application

Abstract

A prototype contact-type micro piezoresistive shear-stress sensor that can be utilized to measure the shear stress between skin of stump and socket of above-knee (AK) prosthesis was designed, fabricated and tested. Micro-electro-mechanical system (MEMS) technology has been chosen for the design because of the low cost, small size and adaptability to this application. In this paper, the finite element method (FEM) package ANSYS has been employed for the stress analysis of the micro shear-stress sensors. The sensors contain two transducers that will transform the stresses into an output voltage. In the developed sensor, a 3000 3000 300 m 3 square membrane is formed by bulk micromaching of an n-type 100 monolithic silicon. The piezoresistive strain gauges were implanted with boron ions with a dose of 10 15 atoms/cm 2 . Static characteristics of the shear sensor were determined through a series of calibration tests. The fabricated sensor exhibits a sensitivity of 0.13 mV/mA-MPa for a 1.4 N full scales shear force range and the overall mean hysteresis error is than 3.5%. In addition, the results simulated by FEM are validated by comparison with experimental investigations. [607]Index Terms-Finite element method, micro-electro-mechanical system, piezoresistive, shear-stress sensor, transducer.

Modelling and Design of MEMS Piezoresistive Out-of-Plane Shear and Normal Stress Sensors

“…Shear forces can be determined based on the change of resistance in these four resistors caused by the deformation of diaphragm. Hsieh [12] designed a micro-shear stress sensor utilizing four-terminal silicon pressure structure and piezoresistiors for an Above-Knee Prosthesis Application. Using liquid metal alloy encapsulated in PDMS substrate as piezoresistive material, and adopting diaphragm sensor structure, a normal and shear force sensor was developed [13,14].…”

Design and calibration of a six-axis MEMS sensor array for use in scoliosis correction surgery

“…Several multi-axis sensors utilizing piezoresistive sensing schemes have been presented in literature [10][11][12][13][14][15][16][17][18]. These devices generally make use of varying stress distribution patterns to detect applied multi-axis loads, integrating the piezoresistive elements to produce voltage outputs corresponding to the stresses at significant regions.…”

“…These devices generally make use of varying stress distribution patterns to detect applied multi-axis loads, integrating the piezoresistive elements to produce voltage outputs corresponding to the stresses at significant regions. Applications for multi-axis sensors include tactile sensing [10,14,16,19,20], robotics [13,14,20,21], and biomedical or biomechanical applications [11,[22][23][24][25][26][27]. Regardless of the application, the nature for the calibration of devices should utilize calibration forces and moments which are similar in magnitude and application method to the loads that the sensors will detect in the field.…”

Parametric evaluation of shear sensitivity in piezoresistive interfacial force sensors

“…Microelectromechanical system (MEMS) devices are particularly well suited for detection of loading in applications where space is limited or compact size is a necessity. MEMS sensors utilizing piezoresistive sensing schemes are commonly used for pressure and tactile sensing applications, both of which operate on the principle that the applied load creates a stress distribution in a piezoresistive sensor region, and electrical output signals are produced to allow quantification of this load [1][2][3][4][5][6][7][8][9][10][11][12][13]. Despite the similarities in the operation of these devices, differences in the geometric design allow devices with varying sensitivity and differing axes of detection to be developed.…”

“…This type of MEMS sensor detects deformation of a membrane in response to a pressure differential, and as such is only sensitive to 1D input. Piezoresistive membrane devices have also been used to measure interfacial forces [3,[5][6][7][11][12][13][14]. In these devices, multiple sensing elements can be implemented on each membrane to resolve shear and normal loads in combination.…”