An antibacterial sensitive wearable biosensor enabled by engineered metal-boride-based organic electrochemical transistors and hydrogel microneedles

Abstract

Cortisol, an essential stress hormone, plays a crucial role in health monitoring, with wearable sensors providing an efficient non-invasive means for continuous tracking. However, tackling the dual challenges of maintaining high sensitivity over extended monitoring periods and preventing bacterial contamination within wearable devices remains critical. To overcome challenges in detecting low-concentration biomarkers in sweat while mitigating bacterial proliferation, we developed an innovative wearable system integrating hydrogel microneedles (HMN) with silver nanowire/nanoparticle-engineered metal boride (AgNWs@AgNPs@MBene)-based organic electrochemical transistors (OECTs). The device employs polyvinyl alcohol/polyvinyl pyrrolidone (PVA/PVP) hydrogel microneedles to enhance transdermal biomarker extraction from sweat, significantly improving the biosensor sensitivity. Experimental validation confirmed that the microneedles effectively penetrated nude mouse skin to facilitate biomarker release, while COMSOL simulations quantitatively analyzed their mechanical stress distribution. Targeting cortisol—a critical adrenal hormone—the device integrates AgNWs@AgNPs-engineered MBene, achieving an ultra-low limit of detection (LOD) of 0.26 pg mL⁻¹. Silver nanomaterial-derived antibacterial properties further suppress bacterial growth risks during prolonged wear. In human volunteers and nude mouse models, the wearable system successfully detected exercise-triggered cortisol fluctuations, demonstrating clinical relevance. This study advances the integration of hydrogel microneedles with functionalized two-dimensional materials, offering a roadmap for developing a comfortable, sensitive, and infection-resistant health monitoring platform.