A Sensor Patch for Continuous Monitoring of Sodium, Glucose, and Ketones Concurrently and in Real-Time - Precision nutrition is an emerging field that recognizes human physiological individuality and exploits it to procure dietary recommendations and/or interventions to improve one’s health and aid in disease prevention, and management. Metabolic profiling, which involves quantifying biochemical changes caused by dietary intake, is essential in deciphering the complex connection between diet and health status, and therefore is a critical tool to enable precision nutrition. Recently, wearable biochemical sensing devices have emerged as convenient method to monitor these chemical changes continuously and in real-time, and they are thus poised to significantly progress the field. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) seeks a smart wearable device for continuous monitoring of circulating or interstitial nutrients, metabolites, or hormones relevant to diet and nutrition. Accordingly, the goal of our proposed project is to develop a wearable device capable of continuously and simultaneously measuring, storing, and displaying interstitial levels of multiple nutritionally relevant analytes, including sodium, glucose, and ketone, in real time. Sodium, glucose, and ketone bodies are all essential indicators for overall health and bodily function, and the continuous and simultaneous monitoring of their levels within the body could offer invaluable clinically- and nutritionally- relevant information. To date, no FDA-cleared, commercially available device exists for the continuous monitoring of multiple analytes. In this context, ActioX LLC. has developed an integrated wirelessly operated wearable sensor platform, based on a biocompatible array of microneedles, to enable pain-free continuous analysis of biochemicals via interstitial fluid (ISF) just few hundred microns under the skin. This SBIR Phase I project will leverage this innovative technology to create a multiplexed and multimodal wearable device that can monitor a panel of putative nutrients for one week of continuous operation. To achieve this, readjustments will be performed at sensor, electronics, and smart phone app levels. Aim 1 constitutes in-vitro feasibility studies to find the best chemical modification strategy with optimal sensitivity, selectivity, reproducibility, and extended 7-days stability while minimizing cross- reactivity among different sensors. Aim 2 will involve electronic hardware design and development to enable concurrent amperometry and potentiometry measurements to expand the detection capabilities of the wearable platform. Upon successful completion of Phase I, Phase II will focus on demonstrating the utility and establishing reliability of the multiplexed sensor via extensive clinical studies in human subjects. By enabling real-time data collection of sodium, glucose, and ketone concurrently, the proposed wearable device will serve various environments, including research programs, clinics, and consumer use to promote general health and wellness. The foundational insights from this work will set the stage for accomplishing our long-term vision – a “lab-under- the-skin,” wherein a wide panel of nutrients and metabolites can be monitored using a miniaturized skin patch, thereby becoming a cornerstone of Precision Nutrition.