Wireless Smart Microneedle Patches for Real-time Continuous Glucose Monitoring of Diabetes

Microneedles (MN) have been widely investigated for biomedical applications with the unique capability of reaching dermal interstitial fluid (ISF) in a minimally invasive way. The analysis of glucose concentrations in ISF with MNs can benefit diabetic patients with facile and pain-free diagnosis compared to the conventional continuous glucose monitoring (CGM) devices. However, CGM using MNs has many limitations including slow response time, low mechanical strength and low stability of glucose monitoring. Here, we developed a wireless, highly sensitive CGM MN system to electrochemically detect glucose with bimetallic nanocatalysts and glucose oxidase using the glucose sample of ISF transferred through the mesoporous polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) hydrogel MNs. The mesoporous structure of MNs reduced the response time by facilitating the rapid diffusion of analytes from ISF to the sensing interface. Chronoamperometry measurements showed that the MN system had high sensitivity, a low detection limit, minimal hysteresis, and remarkably short response times at the glucose concentration from 1 mg/dL to 200 mg/dL. Mechanical tests conducted using the Instron and porcine skin confirmed the sufficient mechanical strength for skin penetration and sensor functionality. The integrated wireless smart microneedle patches will be presented for the real-time glucose monitoring of diabetes.