Lactate is an important biomarker due to its excessive production by the body during anerobic metabolism. Existing methods for electrochemical lactate detection require the use of an external power source. This work present a light air-breathing bio-microfluidic fuel cell (BµFC) operated with 20 mM lactate in phosphate buffer pH 6.5 as fuel and the integration of an air-exposed electrode as cathode enabling oxygen delivery directly from air. FcMe2-LPEI/LOx (dimethylferrocene-modified linear poly(ethylenimine) hidrogel to simultaneously immobilize and mediate electron transfer from lactate oxidase) and An-CNT/BOD (anthracene-modified multi-walled carbon nanotubes, Bilirubine oxidase, 50mM phosphate buffer at pH 6.5, and TBAB-modified Nafion) were employed as electrocatalyst for anode and cathode respectively.

An open circuit potential and maximum power density of 0.855V and 0.125mW cm^-2 (at 0.3V) were obtained respectively, meanwhile the maximum current density was 1.01 mA cm^_2. Although this air-breathing BµFC requires technological improvements before being tested in a biomedical device, show potential possibilities, it represents the best performance to date for a microfluidic fuel cell using lactate as fuel.