Porous microneedle electrodes with pores of ∼1 µm diameter were fabricated by electroless plating of nickel followed by gold on a polymer monolith of poly(glycidyl methacrylate). The specific surface area of the fabricated electrode evaluated by the Brunauer-Emmett-Teller method was 2.559 ± 0.050 m2 g−1 (standard error of mean), while that of the non-porous control was <0.001 m2 g−1. Electrochemical glucose sensors were then fabricated by immobilizing glucose oxidase on the gold-plated microneedle electrodes. The sensitivity of the porous microneedle glucose sensor between 0 and 15 mM glucose was 22.99 ± 0.72 µA mM−1, and that of the non-porous control was 3.16 ± 0.56 µA mM−1. The amperometry of glucose concentration in solution was demonstrated using the fabricated electrode as a working electrode, along with an Ag/AgCl reference electrode and gold counter electrode both of which were made of microneedles. These results indicate the advantages of porous structures for electrochemical sensing with increased sensitivity.
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