Photopatternable Skin Adhesive and Gel Electrolyte Integrated Microneedle Sensor for Enhanced Continuous Glucose Monitoring

Microneedle-based electrochemical biosensors are crucial for continuous monitoring of glucose levels in patients with chronic diseases. These sensors require soft materials like gel electrolytes and skin adhesives to integrate electrically and physically with the skin, ensuring stable and continuous measurements. However, current patterning methods for these soft materials are labor-intensive, time-consuming, and have low compatibility with various device types, especially three-dimensional microneedles. This poses a challenge for widespread application in different devices.<br/>We present a conformable microneedle sensor utilizing a novel photopatternable gel electrolyte and skin adhesive, specifically designed for reliable glucose monitoring. The photopatternable materials enable precise and direct deposition onto the microneedle substrate, overcoming previous limitations. Our study employs oxygen inhibition photolithography to pattern the gel electrolyte and modifies a thermocurable adhesive for positive photolithography. The gel electrolyte was patterned with a resolution of 400 μm, and the skin adhesive achieved a resolution of 500 μm, ensuring precise application and integration with the microneedle substrate. This approach allows for the creation of stable, free-standing patterns directly on the microneedle substrate, enhancing the device's integration with the skin.<br/>The resulting microneedle sensor exhibits a stable electrical and physical interface with the skin and demonstrates high sensitivity across a broad range of glucose concentrations. The sensor's performance was validated through continuous glucose monitoring in an anesthetized rat model, successfully diagnosing hyperglycemia. The sensor maintained stable impedance and adhesion over extended periods, confirming its practical application for continuous monitoring. It also showed noise-free results during glucose monitoring, ensuring accurate and reliable measurements. Our findings indicate that the integration of photopatternable soft materials significantly improves the fabrication efficiency and functionality of microneedle sensors. This advancement has the potential to accelerate the development of wearable biomedical devices, offering a cost-effective and reliable solution for continuous glucose monitoring.