Combined FIM-PHI-Based Wearable Biosensor

Abstract

Focused impedance method (FIM) is a simple non-invasive way of diagnosing epidermal tissue health by subsequent measurements of localized impedance using a set of tetra-polar orthogonal electrodes. The concept is further advanced to an increased number of electrodes with repeated FIM cells that combinedly form a pigeon hole image (PHI) and used to diagnose a range of physiological conditions and disorders. In this work, a wearable imaging device has been demonstrated by combining the attributes of FIM-based pigeon hole imaging and utilised them for detecting unusual body mass within a biological system. The device uses a total of twenty-five Cu electrodes uniformly distributed over a spatial area <inline-formula> <tex-math notation="LaTeX">${A} = 16$ </tex-math></inline-formula> cm² which combinedly form the 16 elements of a <inline-formula> <tex-math notation="LaTeX">$4\times 4$ </tex-math></inline-formula> PHI matrix. The PHI device is capable to produce a 2D crude image of bio-impedance with a pixel resolution of 1 cm and visualise an unusual body mass underneath the testing surface at depth, <inline-formula> <tex-math notation="LaTeX">${d}_{p} \sim 0.3$ </tex-math></inline-formula> to 2.0 cm. The ubiquitous functionality of the device has been demonstrated by integrating into a custom made flexible fabric as wearable wrist band that measures the PHI image and recognizes three common gesture positions using a well-known artificial neural network classifier. The wearable device can be an emerging telemedicine solution for rapid screening of a range of abnormal physiological phenomenon at patient&#x2019;s home or in a regional hospital with resource limited settings.