PZT and PNIPAM Film-Based Flexible and Stretchable Electronics for Knee Health Monitoring and Enhanced Drug Delivery

Abstract

This paper presents a flexible and stretchable electronic device with multi-functionality. This device contains a functional node array coated in smart materials and can be packaged with biocompatible polydimethylsiloxane (PDMS) films as a smart patch. Two kinds of smart materials are utilized: piezoelectric lead zirconate titanate (PZT) film for sensing acoustic emission (AE) waves and thermally activated poly (N-isopropylacrylamide) film for drug delivery. The functional node array is implemented on a thin flexible titanium sheet with an electrically connected serpentine network. This design has two advantages: 1) the serpentine network allows the node array to stretch in an arbitrary planar direction and 2) while the patch is stretched, the normal force exerted by the node can enhance the AE detection head’s coupling to the sensing object as well as increase the contact force and area of the PNIPAM film. The fabrication and experimental results of the designed serpentine-network AE-sensing structure, along with the temperature-controlled drug-release element, is described. The fabricated stretchable and flexible electronic device, assembled with a knee-band strap to examine the AE signals from the knee while executing hopping and jumping as well as walking motions, is also discussed.