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

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.