Freestanding BaTiO3-Au Vertically Aligned Nanocomposite toward Flexible Multi-Sensing Platform

Abstract

Flexible and wearable sensors show enormous potential for personalized healthcare devices by real-time monitoring of an individual's health. Typically, a single functional material is selected for one sensor to sense a particular physical signal while multiple materials will be selected for multi-mode sensing. Vertically aligned nanocomposites (VANs) have recently demonstrated various material combinations and novel coupled multifunctionalities that are hard to achieve in any single-phase material alone, including multiphase multiferroics, magneto-optic coupling, and strong magnetic and optical anisotropy. Integrating these novel VANs into wearable sensors shows enormous potential in multi-mode sensing owing to their multifunctional nature. In this work, the transfer of VANs onto polydimethylsiloxane as a novel flexible chemical and pressure sensor is demonstrated. For this demonstration, the classical BaTiO3 -Au VAN with combined plasmonic and piezoelectric properties is used to demonstrate a multi-sensing mechanism. A thin water-soluble buffer of Sr3Al2O6 serves as a buffer layer for the epitaxial growth and transfer process. The electrical output based on the piezoelectric responses and identifying 4-mercaptobenzoic acid by surface-enhanced Raman spectroscopy reveal great potential for free-standing VANs in a wearable multifunctional sensing platform.