Flexible Paper-Based Capacitive Touchpad for Wireless Switching Control Fabricated via Facile and Solvent-Free Method

Due to the substantial growth in the use of electronic devices in our daily lives, the demand for flexible and green input interfaces has increased as a mean to accommodate more sustainable Human Machine Interface (HMI) options for consumers. Furthermore, capacitive touch sensors are more fabrication-friendly, sensitive, and responsive than traditional physical tactile buttons input interfaces. In this regard we have presented a flexible paper-based capacitive touchpad input interface fabricated through a facile, solvent-free eco-friendly method. Considering greenhouse gases and electronic waste conventionally associated with the electronic device lifecycle, non-toxic and recyclable materials in particular copper and paper are used to fabricate the touchpad. Copper tape is used as touch sensing electrodes, while cellulose-based printing paper is used as a substrate to support the electrodes. Furthermore, the touchpad implementation is facile and only requires off-the-shelf materials readily available easily in a home or laboratory settings. The touchpad flexibility allows bending, warping, twisting, and tugging to desired shape and size without causing a signal change in the functionality. The electrodes of the touchpad are touch-sensitive and sense the capacitance change caused by the effective capacitance of the skin with the help of a microcontroller. The touch-sensitive electrodes have very little intrinsic capacitance, and the response time of the implemented touchpad is excessive. Wireless digital switch control is also interfaced with the touchpad using the Wi-Fi equipped microcontroller. An RGB LED analogy successfully demonstrates the touchpad's functionality reported for controlling digital switches wirelessly. According to the study's findings, there is a very promising application scope for such a touchpad interface system in environment friendly, low cost, disposable HMI(s) that have a facile fabrication method. People with impairments, the elderly, educational institutions, healthcare providers and the entertainment industry can benefit from this adaptable, eco-friendly, responsive, inexpensive, lightweight, non-toxic, thin capacitive touchpad.