Towards a transdermal membrane biosensor for the detection of lactate in body fluids

Here, we report the development of a transdermal membrane biosensor for the electrochemical detection of lactate in body fluids, a key health indicator. Three membrane electrodes, including a gold working electrode, a gold counter electrode, and a stable built-in solid-state Ag/AgCl electrode, were attached to a microneedle array that pierces the human skin painlessly to extract a small volume of body fluids, and perform in-situ lactate detection. The surface of the working electrode was functionalized with lactate oxidase immobilized in an albumin matrix. Mass extraction as a function of pressure was measured. The performance of the transdermal membrane biosensor was evaluated in buffer solutions and blood plasma. Its dynamic range of detection was experimentally determined to be 1–30 mM, which covers the clinically-relevant range of lactate levels related to several abnormal conditions such as lactic acidosis. This work demonstrates the feasibility of using transdermal membrane biosensors with a simple configuration to detect lactate and potentially other chemical indicators (e.g. glucose) for real-time health monitoring. © 2020 Elsevier B.V.