Water‐Based Conductive Ink Formulations for Enzyme‐Based Wearable Biosensors

Abstract

Herein, this work reports the first example of second‐generation wearable biosensor arrays based on a printed electrode technology involving a water‐based graphite ink, for the simultaneous detection of l ‐lactate and d ‐glucose. The water‐based graphite ink is deposited onto a flexible polyethylene terephthalate sheet, namely stencil‐printed graphite (SPG) electrodes, and further modified with [Os(bpy) 2 (Cl)(PVI) 10 ] as an osmium redox polymer to shuttle the electrons from the redox center of lactate oxidase from Aerococcus viridans (LOx) and gluocose oxidase from Aspergillus niger (GOx). The proposed biosensor array exhibits a limit of detection as low as (9.0 ± 1.0) × 10 −6 m for LOx/SPG‐[Os(bpy) 2 (Cl)(PVI) 10 ] and (3.0 ± 0.5) × 10 −6 m for GOx/SPG‐[Os(bpy) 2 (Cl)(PVI) 10 ], a sensitivity as high as 1.32 μA m m −1 for LOx/SPG‐[Os(bpy) 2 (Cl)(PVI) 10 ] and 28.4 μA m m −1 for GOx/SPG‐[Os(bpy) 2 (Cl)(PVI) 10 ]. The technology is also selective when tested in buffer and artificial sweat and is endowed with an operational/storage stability of ≈80% of the initial signal retained after 20 days. Finally, the proposed array is integrated in a wristband and successfully tested for the continuous monitoring of l ‐lactate and d ‐glucose in a healthy volunteer during daily activity. This is foreseen as a real‐time wearable device for sport‐medicine and healthcare applications.