A design-to-translation framework for microneedle electrochemical sensors for continuous biochemical monitoring

Microneedle-based electrochemical sensors have been dominating the field of biochemical monitoring by providing miniaturized biointerfaces with the ability to transduce biochemical information from our body into electrical signals. These sensors have demonstrated the capability to continuously profile physiologically and clinically relevant biomarkers, therefore supporting timely decision-making processes and potentially aiding in the diagnosis and treatment of various diseases. Despite several recent publications demonstrating accurate in vivo continuous profiling, significant analytical challenges remain, particularly in enhancing the stability of these sensors for long-term continuous monitoring. This review provides a rational guide for designing conductive microneedle architectures and describes subsequent functionalization strategies for developing reliable sensor electrodes. Furthermore, a comprehensive framework of the full analytical characterization of microneedle-based electrochemical sensors is provided, from in vitro evaluation to in vivo tests. This roadmap will assist sensor developers in evaluating the analytical capabilities and maximizing their success in the in vivo validation. Crucially, the remaining analytical challenges for microneedle-based electrochemical sensors are described, and potential solutions are presented. In the last section, the review delineates advances in microneedle-based electrochemical sensors, emphasizing the integration of diverse technologies with sensors to develop the next generation of self-powered and intelligent medical devices. These innovations aim to facilitate the wearable long-term monitoring of valuable biomarkers, thereby enhancing the quality of life of patients and users.