title: Development and validation of a 3D-printed interfacial stress sensor for prosthetic applications.
abstract: A novel capacitance-based sensor designed for monitoring mechanical stresses at the stump-socket interface of lower-limb amputees is described. It provides practical means of measuring pressure and shear stresses simultaneously. In particular, it comprises of a flexible frame (20 mm × 20 mm), with thickness of 4mm. By employing rapid prototyping technology in its fabrication, it offers a low-cost and versatile solution, with capability of adopting bespoke shapes of lower-limb residua. The sensor was first analysed using finite element analysis (FEA) and then evaluated using lab-based electromechanical tests. The results validate that the sensor is capable of monitoring both pressure and shear at stresses up to 350 kPa and 80 kPa, respectively. A post-signal processing model is developed to induce pressure and shear stresses, respectively. The effective separation of pressure and shear signals can be potentially advantageous for sensor calibration in clinical applications. The sensor also demonstrates high linearity (approx. 5-8%) and high pressure (approx. 1.3 kPa) and shear (approx. 0.6 kPa) stress resolution performance. Accordingly, the sensor offers the potential for exploitation as an assistive tool to both evaluate prosthetic socket fitting in clinical settings and alert amputees in home settings of excessive loading at the stump-socket interface, effectively preventing stump tissue breakdown at an early stage.
authors.affiliation: Faculty of Engineering and the Environment, University of Southampton, UK.
authors.forename: P
authors.initials: P
authors.lastname: Laszczak
authors.affiliation: Faculty of Engineering and the Environment, University of Southampton, UK.
authors.forename: L
authors.initials: L
authors.lastname: Jiang
authors.affiliation: Faculty of Health Sciences, University of Southampton, UK.
authors.forename: D L
authors.initials: DL
authors.lastname: Bader
authors.affiliation: Chas A Blatchford & Sons Ltd., Endolite Technology Centre, Kingsland Business Park, Hampshire RG24 8PZ, UK.
authors.forename: D
authors.initials: D
authors.lastname: Moser
authors.affiliation: Chas A Blatchford & Sons Ltd., Endolite Technology Centre, Kingsland Business Park, Hampshire RG24 8PZ, UK.
authors.forename: S
authors.initials: S
authors.lastname: Zahedi
mesh_terms: D000672:Amputation Stumps / Q000503:physiopathology; D001186:Artificial Limbs; D020724:Elastomers; D025802:Electric Capacitance; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D007866:Leg; D007871:Leg Ulcer / Q000517:prevention & control; D016014:Linear Models; D018583:Pliability; D011312:Pressure; D066330:Printing, Three-Dimensional; D012815:Signal Processing, Computer-Assisted; D013314:Stress, Mechanical
chemical_list: D020724:Elastomers
keywords: Interfacial sensors; Lower-limb amputees; Stump ulcers; Stump–socket interface