Fabrication of Flexible Thin Film Strain Sensors using Kapton Tape as Stencil Mask

Demand for a flexible and foot plantar pressure sensor to monitor abnormalities in locomotor activities in our day to day life is highly important particularly for patients with osteoarthritis. These should have better sensitivity and spatial resolution than the conventional pressure mats and force resistive sensors. Present paper discusses the development of a miniaturized thin film strain sensor over a flexible PDMS elastomeric surface which can be a generic one to measure the strain under the foot and can be used to map and study the foot pressure distribution by both the legs for analysis of various limb problems, pain or foot ulceration using an array of similar flexible metal strain gauges. In the present work, aluminium strain sensor has been fabricated through thin film deposition technique using Kapton tape as a low-cost stencil mask with a resistance value of ~ 12.65 Ω. The corresponding strain analysis has also been modeled using COMSOL Multiphysics® 5.3a. Initial simulation result shows a resistance value of 42 Ω for a similar configuration which shows good correlation between the two under unstrained condition and increases with increasing pressure. Based on foot pressure mapping from an array of such strain sensors, osteoarthritis and other locomotive abnormalities can be diagnosed at an earlier stage in the long run.