Mediator-free electron-transfer on patternable hierarchical meso/macro porous bienzyme interface for highly-sensitive sweat glucose and surface electromyography monitoring

Abstract

Wearable electrochemical biosensors, which measure the concentration of small biochemical molecules in biofluids in a non-invasive way, are still highly desired. Herein, a wearable, mediator-free electrochemical biosensor for real-time sweat glucose monitoring is proposed. A flexible and hierarchical meso/macro porous carbon nanotubes (CNT) - ethylene-vinyl acetate copolymer (EVA) film is constructed as the sensing substrate in a facile route. Thanks to its well-formed three-dimensional conductive nanoporous structure, direct electron transfer-type of bioelectrocatalysis is successfully realized on the glucose oxidase-horseradish peroxidase bienzyme functionalized CNT-EVA film for glucose monitoring without any mediator. The as-fabricated biosensors show excellent selectivity to glucose with a super-high sensitivity of 270 ± 10 μA mM−1 cm−2. This flexible CNT-EVA films also are utilized for monitoring the surface electromyography (sEMG) with high signal-to-background sensitivity due to its high electrical conductivity as well as good conformability to the skin. On-body experiments illustrated the capability of the proposed flexible biosensor for monitoring sweat glucose and surface electromyography simultaneously, guiding the way for measuring multiplex physiological signals for health monitoring, early diagnosis, and clinical research in future.