Conjugated Metal‐Organic Frameworks on Laser‐Induced‐Graphene Scaffold Enable Picomolar Sensitivity in Electrical Biosensors

ABSTRACT Conjugated metal–organic frameworks (c‐MOFs) are a promising class of materials thanks to their high surface area, abundant active sites, and intrinsic electrical conductivity. However, their integration into electronic devices remains challenging, especially in forming uniform 3D thin films. Here, we present a versatile strategy for the layer‐by‐layer (LbL) growth of a conductive MOF film, copper hexaiminotriphenylene (CuHITP), onto a 3D laser‐induced graphene (LIG) scaffold. The LIG template, prepared by femtosecond laser irradiation of polyimide, provides a hierarchical macroporous structure that increases the accessible surface area for MOF nucleation and bioreceptor immobilization. The resulting CuHITP layer conformally replicates the LIG structure while maintaining extended π‐conjugation and high conductivity. When integrated into an extended‐gate field‐effect transistor (EG‐FET), the CuHITP/LIG hybrid enables sensitive cortisol detection. By exploiting both the amine functionalities and unsaturated metal sites of the MOF framework, we achieve stable covalent and coordination‐based immobilization of thiolated aptamers. The sensor exhibits a wide detection range from 1 pM to 10 µM in diluted buffer and retains sub‐picomolar sensitivity in artificial sweat. This work highlights a robust approach for integrating c‐MOFs into electronic biosensors and advances the development of non‐invasive health‐monitoring platforms.