Dual photonic electrochemical lab on a chip for lactate detection in continuous flow mode

An integrated lab on a chip that enables simultaneous optical and electrochemical analysis working in continuous flow mode is presented. Both transducers are integrated into a single detection cell and operated simultaneously with no evidences of cross-talk and in agreement with theoretical predictions by Levich equation (electrochemical) and by Lambert-Beer law (absorbance). Their performance is demonstrated by continuous detection of lactate via a double enzymatic reaction with lactate oxidase (LOX) and horseradish peroxidase (HRP). The consumption of the enzymatic reaction mediator (ferrocyanide, [Fe(CN)₆]^4-) is recorded by amperometry, while the product (ferricyanide, [Fe(CN)₆]^3-) is quantified by absorbance. The ability to quantify reagent and product simultaneously increases the robustness of the system by making it self-verifying, in addition to the inherent advantages of microfluidic devices.