Smart Bandage with Inductor-Capacitor Resonant Tank Based Printed Wireless Pressure Sensor on Electrospun Poly-L-Lactide Nanofibers

Easy to use multifunctional wearable devices, with no wires hanging around, are needed for real time health monitoring at user's comfort. Herein, an inductor-capacitor (LC) resonant tank-based wireless pressure sensor, screen-printed on an electrospun Poly-L-lactide (PLLA) nanofibers-based flexible, biocompatible, and piezoelectric substrate is presented. The printed resonant tank (resonant frequency of ≈13.56 MHz) consists of a planar inductor connected in parallel with an interdigitated capacitor. The capacitance, of the interdigitated capacitor present on the piezoelectric substrate varies in response to applied pressure. As a result, the resonant frequency changes and the LC tank works as a wireless pressure sensor. The sensor exhibited high sensitivity 0.035 kP⁻¹ and 1200 Hz kPa⁻¹ in wireless operation with excellent durability (over 1800 cycles). The sensitivity is the highest (1.75-fold higher) among printed wireless pressure sensors reported so far. Finally, the presented LC tank-based pressure sensor is integrated on a compression bandage to demonstrate its potential use in the online monitoring of sub-bandage pressure. The application of optimum pressure by the bandage, together with the electroceutical arrangement facilitated by the piezoelectric PLLA substrate, can accelerate the cell regeneration and hence wound healing.