Our group previously demonstrated a “neural dust” system for neural recording which includes an implantable device and external ultrasonic transducers to power and communicate with the implantable. In this work, we extend that paradigm, demonstrating an implantable that can measure and report tissue oxygenation. Oxygenation state is a key parameter when assessing the metabolic state of cells and tissues, tissue and organ viability, tumor state, among many examples in both basic science and clinical care. Various types of methods for the detection of oxygen have appeared in recent years, including the Clark electrode, Winkler titration, and optical sensing. Among these, there is a growing interest in optical sensors for use in consumer electronic devices because they possess advantages of (a) fast response, (b) high sensitivity, (c) good precision and accuracy, (d) lack of oxygen consumption during measurements, (e) ease of miniaturization, (f) low cost, and (g) enabling in vivo, non-invasive and real- time measurements. In this project, we aim to develop a miniaturized oxygen sensor system consisting of a micro-light emitting diodes (LEDs) for optical excitation, bio- compatible thin-film for encapsulation of an oxygen-sensitive fluorophore, ultrasonic transducer for wireless communication and wireless powering of the implantable device, and single-chip CMOS integrated circuit for optical detection and signal processing. The sensor system determines oxygen level utilizing the fluorescence lifetime of a fluorophore, which is a function of the oxygen concentration of the thin film that is influenced by the surrounding environment.
Project end: 08/01/2022