Kirigami technique for the design of printed flexible capacitive sensors

Abstract

In the past decade, the field of flexible and wearable technology has emerged as a focal point of research and innovation, captivating the interest of scientists, engineers, and healthcare professionals alike. Flexible sensors and electronics represent a promising turning point in various fields such as healthcare monitoring, human-computer interaction, and sports performance tracking, among others. Capacitive sensors are a promising non-invasive sensing technique that enables ubiquitous and long-term monitoring of biopotential signals without the need for technical preparation and medical settings. The exploitation of flexible and conformable electronics for capacitive sensing is a promising option to improve the seamless integration of these types of sensors into the patient’s everyday life, while also improving the performance and quality of the sensing technique. In this work we propose the conceptualization, realization, and characterization of a novel Flexible Hybrid Electronics design method for capacitive sensors, using Kirigami. The Japanese artistic technique is explored as an additive, easy-to-implement technique applied to Printed Electronics to improve the flexibility and conformability of capacitive electrodes and allow the coherent integration of rigid components on the sensor without affecting its flexibility. First, different versions of Kirigami designs were performed on a printed capacitive electrode. Their capacitive behavior was evaluated when applied to non-flat second plates of diverse dimensions, and compared to the corresponding non-cut printed electrode. An analytical model to describe the capacitive behavior of the Kirigami flexible electrode was then defined, serving as an effective tool to understand the effect of the Kirigami structure on the improved conformability, and consequently the capacitive performance, of the electrode. The novel designed sensor structure is examined in its most important electrical characteristics: capacitive coupling ability, signal transmission amplitude, and cutoff frequency. Its behavior in response to the most common motion artifacts was evaluated: the application of the sensor to bodies of different shapes and dimensions, and with different pressures applied on top were tested, in order to measure the variations of the required signal in the diverse situations. The triboelectric behavior of the sensor was also investigated. The case of the sensor detaching vertically from a non-flat body was replicated, and the peculiar effect of the flexibility of the sensor on the resulting triboelectric voltage was measured. Finally, the complex behavior was examined and an analytical model was defined, which constitutes a powerful tool to help the general understanding of the triboelectric behavior of flexible sensors.

Date	26 Nov 2024
Original language	American English
Awarding Institution	École de technologie supérieure
Supervisor	Ricardo J. Zednik (Supervisor) & Ghyslain Gagnon (Co-supervisor)