Direct, One-Step Growth of NiSe₂ on Cellulose Paper: A Low-Cost, Flexible, and Wearable with Smartphone Enabled Multifunctional Sensing Platform for Customized Noninvasive Personal Healthcare Monitoring

Monitoring of personal healthcare requires multifunctional sensors that can sense both chemical and physical stimuli. One of the possible solutions is the fabrication of low-cost, disposable “one time use” functional nanomaterials based sensors that can sense multiple health parameters, and the sensor data can be wirelessly transmitted to the smartphone for further processing. This report is a first demonstration of the direct growth of NiSe₂ on cellulose paper by the solution processed hydrothermal method and its application for a smart personal healthcare monitoring system that includes a noninvasive periodontal diagnosis to monitor oral health by the use of human saliva, a breath analyzer for various breath-related diseases, and a gesture sensor for deaf, dumb, and aurally challenged patients to communicate with the world. The fabricated sensor can be customized for a specific sensing with a dedicated user-friendly Android application which can be accessed remotely by a smartphone. The detailed sensing mechanism of each sensor is explained in terms of charge transport and electron transfer mechanisms. Furthermore, the sensing performance does not fluctuate even after 500 bending cycles for both chemical and physical stimuli, thus enabling low-cost yet robust and reliable monitoring. Successful development of such a versatile platform finds wide applications in the field of smart healthcare, medical devices, and the internet of things.