The promise of implantable electrochemical sensors is often undermined by the critical requirement of device miniaturization that inadvertently degrades sensor performance in terms of sensitivity and selectivity. Herein, we report a novel miniaturized and flexible amperometric sensor grown at the ‘edge plane’ of a 25-µm gold wire. Such geometry affords extreme miniaturization along with ease of fabrication, minimal iR drop and 3-D diffusion for effective mass transfer. This together with electrochemical rebuilding of the Au working electrode and subsequent Pt nanoparticles deposition resulted in the highest H2O2 sensitivity (33 mA·mM−1·cm−2), reported thus far. Concurrent electrodeposition of o-phenylenediamine with glucose oxidase afforded glucose detection at these edge-plane microsensors with a six fold improvement in sensitivity (1.2 mA·mM−1·cm−2) over previous reports. In addition, these sensors exhibit low operation potential (0.3 V), high selectivity (more than 95%) against in vivo interferences, and an apparent Michealis-Menten constant (Kmitalicapp) of 17 and 75 mM of glucose in the absence and presence of an outer polyurethane coating, respectively. These features render the edge-plane sensor architecture as a powerful platform for next-generation implantable biosensors.

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