Design of a wireless smart insole using stretchable microfluidic sensor for gait monitoring

Abstract

Wearable sensor enables continuous and ubiquitous real-time monitoring of the gait pattern of a patient and it eliminates the need of frequent visit to the clinics and the use of costly medical facilities. Attaching gait sensors on body, however, may not be easy as most of the reported gait sensors are made of non-stretchable materials and they are non-conformal to human skin. In this paper, we have presented an in-shoe pressure measurement system that is developed using multiple stretchable microfluidic sensors for monitoring gait parameters ergonomically. The sensor here has employed Eutectic Gallium-Indium (EGaIn) as the conductive liquid to fill up a spiral-patterned microchannel which is encapsulated inside an Ecoflex 00-50 elastomer. Fundamental studies have been performed to investigate the sensor's behaviours when it is exposed to normal and axial applied forces. As proof-of-concept demonstration of the applicability of the proposed sensor for gait monitoring application, we have measured the localised foot pressure and dynamically by attaching two sensors on a shoe insole for detecting pressure changes around the heel and metatarsal regions. The experiment was then extended to evaluate the strain sensing by measuring the ankle angle. It has been shown that data can be captured wirelessly and displayed on a smartphone using the Bluetooth communication protocol. Owing to its unique and stretchable structure, the sensor is able to distinguish walking and running motions by analysing their stance and swing phases. This work has explored the possibility of applying a microfluidic-based structure for designing a wearable gait sensor that has good flexibility.

A Survey of Human Gait-Based Artificial Intelligence Applications

“…The domain of smart gait devices and environments is exciting, brave, creative, extensive, and ever-growing (See Table 12 ). SG devices include wearable shoes ( Zou et al, 2020 ), socks ( Zhang et al, 2020f ), kneepads and anklets ( Totaro et al, 2017 ), insoles ( Low et al, 2020 ), as well as devices attached to the body, such as smartphones ( Poniszewska-Maranda et al, 2019 ), smartwatches ( San-Segundo et al, 2018 ), ( Sigcha et al, 2021 ), etc., implantable medical devices such as ActiGait ( Sturma et al, 2019 ), wearable robotics ( Shi et al, 2019 ) such as prosthetics ( Gao et al, 2020 ) orthotics ( Zhang et al, 2020e ), ( Choo et al, 2021 ), assistive devices such as smart walkers ( Jimenez et al, 2018 ), and environmental devices such as smart tiles ( Daher et al, 2017 ). SG devices use gait data to facilitate health monitoring, including passive mental health assessment ( Rabbi et al, 2011 ) and transfer data to control devices for health, sports, security, and entertainment applications.…”

Closing the Wearable Gap–Part IX: Validation of an Improved Ankle Motion Capture Wearable

“…Low et al [20] describe how a smart, insole-wearable, elastic microfluidic sensor may be used for gait tracking and ankle joint angle measurement. The ankle was moved in plantarflexion and dorsiflexion while the sensors were firmly attached to ankle support.…”

Custom Shoe Sole Design and Modeling Toward 3D Printing

“…In the past years, there has been considerable amount of research in footwear industry to provide best comfort shoes for different walks of people from various fields, such as the sports or health sector; many researchers continue to deliver crucial information based on the experimental and theoretical works[ 19 ]. The stiffness reported as a crucial factor accounts for 70% of the comfort for diabetic users[ 20 ].…”