Stepwise Electrochemical Layer-by-Layer Characterisation for the Controlled Assembly of Multilayered (Bio)sensors

Electrochemical layer-by-layer characterisation (LbL-EC) is emerging as a transformative strategy for designing robust, high-performance electrochemical (Bio)sensors. By enabling in-operando real-time control of multilayer assembly, LbL-EC permits precise tuning of film thickness, composition, and bioreceptor orientation, thereby enhancing sensitivity, stability, and durability. Techniques such as cyclic voltammetry and electrochemical impedance spectroscopy, applied individually or synergistically, provide dynamic insights into deposition processes, interfacial charge transport, and surface loading density while minimising nonspecific interactions. This review examines the mechanisms governing mass and charge transport within polyelectrolyte multilayers and critically explicates the strengths and limitations of LbL-EC in building supramolecular architectures for advanced biosensing. Comparative discussion with conventional imaging methods, including transmission electron microscopy, scanning electron microscopy, atomic force microscopy, and scanning tunnelling microscopy, highlights the unique ability of LbL-EC to couple structural precision with functional optimisation. Collectively, LbL-EC is positioned as a pivotal enabler of next-generation (Bio)sensors with unprecedented reliability and performance.