Sensing Electronics on Ultra-Thin Nanocellulose Sheets

We will describe our ongoing work on the development of sensing electronics on microns-thin bacterial nanocellulose for human monitoring applications. The porosity and hydrophobicity of nanocellulose sheets offer advantages that typical plastics cannot provide, such wicking of analytes and absorption of inks. Our first application is the detection of electrolyte concentration in a bio-fluid sample. We have developed an ultra-thin electronic decal that can simultaneously collect transmit and interrogate the bio-fluid. Our technology effectively integrated a thin-film organic electrochemical transistor (sensing component) with the nanocellulose wicking membrane (sample handling component). The nanocellulose provided robust support and physical isolation of the electronics, and efficient bio-fluid delivery to the transistor via vertical wicking, with high detection efficiencies. For our second application, we developed a printing method to form nanocellulose printed circuit boards (PCBs), and created a simple low temperature soldering process to form circuit structures using standard surface-mount components on our nanocellulose PCBs. This has been used to create nanocellulose decals that measure human body temperature and perform pulse oximetry. For both applications, the fabrication processes are solution-based and requires only ambient processing, and therefore simple, potentially low-cost, and can be aimed for a wide range of applications.