DESIGN AND FABRICATION OF A MICRONEEDLE ION-SELECTIVE SENSOR PATCH: TOWARD MINIMALLY-INVASIVE WEARABLE MONITORING OF BIOMARKERS

Wearable health monitoring devices that provide continuous and real-time feedback on a patient’s health are of great interest in many fields of medicine. Measuring common chemical biomarkers in fluids other than blood with a wearable device could allow minimally-invasive real-time monitoring of a wide variety of medical conditions. Furthermore, a simple-to-use wearable device that does not require trained medical personnel could be easily deployed in resource-limited situations such as home health care or rural communities. In this work, we report the design and fabrication method for a wearable patch sensor to detect biomarkers in interstitial fluid. The design aims to provide a low-cost, easy-to-use device capable of continuous, real-time monitoring of multiple analytes. A microneedle-based ion-selective electrode is designed to penetrate the skin to measure biomarkers such as potassium ion concentration or pH in the interstitial fluid. The patch sensor is fabricated using commercial stainless steel acupuncture needles that are functionalized with a nanoparticle carbon solid contact and an ion-selective membrane. The microneedle sensors are secured in a flexible polymer substrate to create a wearable patch-like device that is robust when inserted into a silicone skin phantom.