Screen printed flexible IDC sensors for pressure sensitive HMIs and breathing applications

Abstract Interdigitated capacitive (IDC) sensors are one of the most commonly used sensors in wearable applications because of their high sensitivity and relatively simple manufacturing process. This is still true despite the numerous advantages of the technique, and its potential for broader sensing applications may be hampered by challenges like multiple mode sensing and environmental parameters, including humidity. In this work, IDC sensors were fabricated on a PET substrate using carbon ink with a screen printing fabrication process. These fabricated sensors portrayed optimal sensitivity to the pressure of human finger touch in detecting low-pressure touch (LPT), medium-pressure touch (MPT), and high-pressure touch (HPT). The sensors proved to be very responsive, with rise and fall times of 11 ms and 15 ms respectively. The stability tests likewise showed the sensor’s consistent performance over 20 000 durability cycles. These IDC sensors were then implemented in wireless pressure-sensitive HMIs to perform various operations like RGB light color control, keyboard operations in Microsoft Word, and gaming interfaces like moving avatars in Free Fire and Tekken 3. The pressure applied by the human finger recognized the pressure-sensitive IDC sensor the system to display different light colors of RBG leds for LPT, MPT, and HPT. The multiple keyboard key operations performed by different finger touch pressures indicate possible real applications like pressure-sensitive keyboards and gaming pads. The IDC sensors’ humidity sensitivity was examined and the sensors were placed in face masks to detect mouth and nasal breathing frequencies based on the humidity of human breath, thus demonstrating potential uses in health care. This design proposes flexible, multi-channel sensing solutions for next-generation interfaces, security, and home automation applications. This entry’s discussion of the stability and reliability of the reported IDC sensors demonstrates the future possibilities of smart sensing and intelligent devices, video game control devices, and smart homes.