A portable device for clinical assessment of foot mobility and toe grip function

Project Number
RP 1/15 KPW

Project Duration
March 2016 - February 2019

In-Progress (Extended)

There is currently no clinical equipment to measure foot joint mobility or to comprehensively evaluate toe grip function. This study will develop a portable, clinically friendly device to measure foot joint mobility and individual toe grip function. The system will be based on the fiber Bragg grating (FBG) technology, an excellent tool for measuring bending and strain due to its unique characteristics such as lightweight, flexible, and immune to electromagnetic interference. To measure foot joint stiffness, the bare FBG embedded in the micro-shape memory alloy tube is tensioned by elastic polymer. Predefined torque or force will applied to move various foot joints through a load cell. Displacement variations of the joint will alter the micro-shape memory alloy tube curve and subsequently inducing a strain variation on the FBG sensor. By measuring the Bragg wavelength shift due to strain, the displacement of the joint can be computed. The stiffness or rotational stiffness of the foot joints can then be calculated. To measure toe grip range of motion, five FBG sensor probes (one for each toe) with different Bragg wavelengths are integrated to a micro-shape memory alloy tube and two copper sheets on a five-toe sock. Wavelength division multiplexing (WDM) interrogation system is employed to simultaneously monitor five Bragg wavelengths shift. During the measurement, patients will grip their toes to the maximum, inducing Bragg wavelengths shift. The toe displacements will be computed by interpolating strain/displacement coefficient of the FBG. After successful development of the device, it will be used in a clinical investigation to 1) assess the test-retest reliability of the measurements, and 2) compare the measurements between individuals with healthy feet and patients with foot deformities. It is hypothesized that the measurements will be reliable and able to differentiate between asymptomatic feet and feet with hallux valgus deformity.

Funding Source

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