3D-printed organic electrochemical transistors on microfluidic paper for multianalyte point-of-care testing

Emerging demands for sustainable point-of-care diagnostics drive the development of paper-based organic electrochemical transistors (OECTs), yet challenges persist in achieving multianalyte detection through scalable manufacturing. A low-cost, flexible, and user-friendly multianalyte biosensing platform has been developed by combining three-dimensional microfluidic paper-based analytical devices (μPADs) with 3D printed OECTs. This platform enables the simultaneous detection of multiple essential blood biomarkers, including ions, glucose, and cholesterol. The platform was designed with closed-channels created by removing parts of the cellulose matrix and leaving the bottom of the channel hydrophilic, which significantly increases the instantaneous flow rate by 2.2-fold compared to conventional open-channels. The biofunctionalized OECT sensors demonstrated exceptional sensitivity in the micromolar (μM) range and robust anti-interference capabilities (NR < 0.07 against common interferents), ensuring reliable detection in complex biological samples. This work demonstrates the feasibility of combining direct ink writing (DIW) with paper-based microfluidics, positioning the platform as a viable solution for resource-limited settings and personalized healthcare with capabilities for extended analyte detection and high-density integration.