High-performance flexible bioelectrocatalysis bioassay system based on a triphase interface

Flexible biosensor technologies are essential for the development of noninvasive bioassays such as those based on sweat or interstitial fluid analysis. Cathodic measurement of oxidase catalytic product H₂O₂ is an ideal principle for analyte detection, with O₂ serving as an electron mediator. Herein, the authors report a flexible bioassay system comprising a flexible superhydrophobic polydimethylsiloxane micropillar array substrate, a noble metal H₂O₂ electrocatalyst-decorated carbon nanotube film, and an oxidase enzyme top layer. The flexible bioassay system possesses a solid–liquid–air triphase bioelectrocatalysis reaction interface where oxygen levels are air phase dependent, hence constant and sufficient, which enhances and stabilizes the oxidase kinetics. In comparison with conventional flexible diphase bioassay systems, when used for analyte detection including but are not limited to glucose, choline, and lactate in body fluids, the triphase bioassay system displays a wide linear dynamic range and high selectivity. Moreover, the flexible bioassay system remains intact and fully operational after being bent over 500 times. Such a system should greatly promote the development of noninvasive biosensors for the monitoring of physiological biomarkers.