Flexible triphase enzyme electrode based on hydrophobic porous PVDF membrane for high-performance bioassays

Flexible bioassays based on oxidase-catalyzed and electrocatalytic cascade reactions have been widely reported. However, the fluctuant oxygen level and high anodic potential restricts the detection accuracy. To overcome these challenges, we report here a flexible triphase enzyme electrode by assembling an oxidase enzyme layer and Pt electrocatalysts onto a carbon nanotube film/porous polyvinylidene fluoride hydrophobic substrate. Such a flexible enzyme electrode has an air-liquid-solid triphase reaction zone where oxygen level is air phase dependent (constant and sufficient high), which stabilized the oxidase kinetics and enabled the cathodic measurement of enzymatic product H₂O₂ with minimum interferents caused from oxygen level fluctuation and many oxidizable species in analyte solution. Furthermore, the flexible triphase enzyme electrode exhibited good mechanical stability even after being bent over 600 times and an excellent air permeability, which are crucial to wearable devices that require long-term skin contact.