Development of capacitive-based soft pressure sensor arrays for e-textiles applications

Abstract

The development of textiles dates back thousands of years as one of the humanity's first material inventions. Textiles have been used to convey messages in artistic or materialistic ways, as well as to protect people from the surroundings. However, today's society has undergone drastic changes recently with the intention of establishing a more intelligent and comfortable world. Soft pressure sensors have attracted a lot of attention in the recent decade owing to their wide range of applications, including human motion recognition, object detection, and human–computer interaction. In this situation, textile-based sensors are a cutting-edge technology that offers sensing capabilities along with flexibility, light weight, and breathability, making them the perfect option for smart gadgets. Due to the difficult and time-consuming methods involved, their large-scale production and availability to end users are limited. Another important drawback is the sensors' lack of scalability in terms of working range, sensitivity and durability making them challenging to utilize in a variety of applications. Therefore, a laborless, rapid, and scalable manufacturing technique for capacitive-based soft pressure sensors with high sensitivity and working range that meet market demands and end-user expectations is proposed in this thesis. The developed manufacturing method enables manipulation of sensor properties by varying production parameters based on specific application needs. The proposed sensor's electrode is made of conductive knit fabric that containing silver nanoparticles (AgNPs), and the dielectric layers are made of thermoplastic polyurethane (TPU) sheets. As a result of the novel approach, it is possible to generate scalable air gaps between electrodes and dielectric layers to capture low pressures of less than 1 kPa. The usage of multi-layer TPU sheets also increases the working range of sensors up to 1000 kPa. The proposed technology is used to create several sensor mats for various purposes, including improved gesture and shape recognition, as well as interactive gaming mats for children.