Perylene Diimide (PDI) based Flexible Multifunctional Sensor Design for Personal Healthcare Monitoring- A Complementary Approach Involving Experimental and Theoretical Investigations

This work demonstrates the Perylene Diimide (PDI) based multifunctional sensor for breath-sensing and Geriatric Emergency Signalling applications fabricated by an economically viable vacuum filtration deposition technique. The deposition of PDI molecules on the flexible substrate forms a moderately conducting percolating molecular network, exhibiting superior pressure and breath-sensing performance. The pressure sensor displays a sensitivity of 2.42198 kPa(-1) with response and recovery times of approximate to 191 and approximate to 166 msec. Also, the sensor displays response and recovery times of approximate to 211 msec and approximate to 2.651 sec for breath sensing. The durability of the sensor is evaluated using a pressure-tapping machine, and the sensor displayed a negligible performance drop over approximate to 10 000 cycles. The experimental findings are complemented by an ab-initio calculation-based comprehensive theoretical analysis of the underlying transduction mechanism for pressure and breath sensing in the context of the percolating molecular network. The theoretical analysis reveals that applied pressure and molecular adsorption significantly influence the molecular conductivity as well as the inter-molecular quantum mechanical tunneling component, which primarily contributes to the observed increase in conductivity with pressure and exposure to breath. An Android/iOS application is developed to wirelessly receive data via Bluetooth from the sensors connected to a microcontroller.