Measurement and Sensor Technology, Technische Universität Chemnitz, Reichenhainer Straße 70, 09126 Chemnitz, Germany.
Composites and Material Compounds, Institute of Material Science and Engineering (IWW), Technische Universität Chemnitz, Erfenschlager Straße 73, 09125 Chemnitz, Germany.
Sensors (Basel). 2021 Sep 10;21(18):6082. doi: 10.3390/s21186082.
Foot pressure measurement plays an essential role in healthcare applications, clinical rehabilitation, sports training and pedestrian navigation. Among various foot pressure measurement techniques, in-shoe sensors are flexible and can measure the pressure distribution accurately. In this paper, we describe the design and characterization of flexible and low-cost multi-walled carbon nanotubes (MWCNT)/Polydimethylsiloxane (PDMS) based pressure sensors for foot pressure monitoring. The sensors have excellent electrical and mechanical properties an show a stable response at constant pressure loadings for over 5000 cycles. They have a high sensitivity of 4.4 kΩ/kPa and the hysteresis effect corresponds to an energy loss of less than 1.7%. The measurement deviation is of maximally 0.13% relative to the maximal relative resistance. The sensors have a measurement range of up to 330 kPa. The experimental investigations show that the sensors have repeatable responses at different pressure loading rates (5 N/s to 50 N/s). In this paper, we focus on the demonstration of the functionality of an in-sole based on MWCNT/PDMS nanocomposite pressure sensors, weighing approx. 9.46 g, by investigating the foot pressure distribution while walking and standing. The foot pressure distribution was investigated by measuring the resistance changes of the pressure sensors for a person while walking and standing. The results show that pressure distribution is higher in the forefoot and the heel while standing in a normal position. The foot pressure distribution is transferred from the heel to the entire foot and further transferred to the forefoot during the first instance of the gait cycle.
足底压力测量在医疗保健应用、临床康复、运动训练和行人导航中起着至关重要的作用。在各种足底压力测量技术中，鞋内传感器具有灵活性，可以准确测量压力分布。在本文中，我们描述了基于多壁碳纳米管 (MWCNT)/聚二甲基硅氧烷 (PDMS) 的柔性和低成本压力传感器的设计和特性，用于足底压力监测。这些传感器具有出色的电气和机械性能，在恒定压力负载下可稳定响应超过 5000 次循环。它们具有 4.4 kΩ/kPa 的高灵敏度，滞后效应对应于小于 1.7%的能量损失。测量偏差最大为相对最大电阻的 0.13%。传感器的测量范围高达 330 kPa。实验研究表明，传感器在不同压力加载速率（5 N/s 至 50 N/s）下具有可重复的响应。在本文中，我们专注于展示基于 MWCNT/PDMS 纳米复合材料压力传感器的鞋垫的功能，该鞋垫重约 9.46 g，通过研究行走和站立时的足底压力分布来实现。通过测量人行走和站立时压力传感器的电阻变化来研究足底压力分布。结果表明，在正常位置站立时，前脚掌和脚跟的压力分布较高。在步态周期的第一次实例中，压力分布从脚跟转移到整个脚，然后进一步转移到前脚掌。
