Electrically Conductive Metal–Organic Framework Thin Film‐Based On‐Chip Micro‐Biosensor: A Platform to Unravel Surface Morphology‐Dependent Biosensing

Abstract Electrically conductive metal–organic frameworks (EC‐MOFs) are suitable for electrochemical sensing because of their unique structure and properties. Herein, an on‐chip electrochemical micro‐biosensor is designed to study the electrocatalytic interfaces, which are generally buried between the solid support and liquid electrolyte in conventional electrochemical sensing methods. The gas–liquid interfacial reaction method is used to obtain a Cu‐benzenehexathiol (Cu‐BHT) thin film with a flat up‐side surface and synaptic‐like structure on the bottom‐side surface. The effect of surface morphology on the film sensing performance is studied using the prepared Cu‐BHT film‐based on‐chip micro‐biosensor. The bottom‐side surface exhibited significantly higher H₂O₂ sensing performance than that of the smooth up‐side surface. The synaptic‐like structure has dense crystal defects (ts‐Cu), which act as nanozymes and play an important role in improving the H₂O₂ sensing performance. This study clarifies the role of crystal defects in Cu‐BHT sensing using the micro‐biosensor and allows the in‐situ study of electrochemical interface of EC‐MOF films during biosensing.