3D Printed Disposable Wireless Ion Sensors with Biocompatible Cellulose Composites

Abstract

AbstractAs the wireless communication technologies are becoming more crucial for internet‐of‐things (IoT) electronic devices, sensors have also been equipped with wireless data collection. A conventional way to make wireless sensor systems is to develop active sensor devices with silicon‐based chip technologies integrated with an amplifier, a battery, a converter, among others. However, it is difficult to generate disposable inexpensive flexible sensors with all these rigid components. Here, 3D printed disposable wireless ion selective sensor systems with unique form factors, high sensitivity, and flexibility are reported. A 3D printable conductive ink is designed and optimized with cellulose nanofibers by addition of silver nanowires for sustainable and biocompatible sensor applications. Polyimide film which has high surface hydrophobicity is used as a substrate for better resolution of printing. The 3D printed wireless sensor system includes inductor–capacitor circuits, and ion selective membrane electrodes, which can detect quantitative ion concentrations selectively. The change of ion concentrations is detected by measuring the magnitude of S11, reflective coefficient at the resonant frequency of 2.36 GHz using a vector network analyzer. The demonstrated sensitivity is 3.4%/ m for ammonium ion (NH4+).