Portable impedance-based microfluidic biofuel cell printed on cellulose substrate for enzymatic urea sensing

Urea, a protein metabolism byproduct in biological samples like blood and urine, requires measurement in fields like healthcare and agriculture. Electrochemical urea sensing holds promise due to real-time measurement, affordability, and portability. This study presents an electrochemical biosensor using a biofuel cell. Urease catalyzes urea into ammonia and CO
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, with ammonia detected electrochemically. The biofuel cell, made using screen-printing Coal-derived graphene oxide on cellulose substrate, exhibits power output in nW and detects 10-100 $\mu \mathrm{M}$ urea concentrations. This self-powered biosensor shows potential for real-time, affordable urea sensing in the future.