A mini review on capacitance cell sensors for real-time cellular monitoring and rapid antimicrobial susceptibility testing

Rapid and reliable monitoring of cellular responses and bacterial drug susceptibility is essential for biomedical research and clinical diagnostics. Conventional optical and biochemical assays, while widely used, often require long processing times and complex procedures, limiting their suitability for time-critical and point-of-care applications. Electrical cell sensors provide a label-free and real-time alternative by detecting changes in dielectric properties induced by cells or bacteria under alternating electric fields. This mini review summarizes recent advances in capacitance sensor arrays for monitoring mammalian cell growth, death, receptor-mediated endocytosis, and stem cell differentiation in both two-dimensional and three-dimensional culture systems. We further highlight the application of bacterial capacitance sensors to electrical antimicrobial susceptibility testing (e-AST), which enables rapid determination of minimum inhibitory concentrations with high agreement to standard clinical methods. Particular emphasis is placed on vertical capacitance sensors that allow direct susceptibility testing in blood samples without subculturing, thereby substantially reducing turnaround time. Finally, the integration of impedance spectroscopy with distribution of relaxation times analysis is discussed as a strategy to deconvolute complex biological signals and achieve early detection of bacterial growth. These developments underscore the potential of capacitance-based biosensing platforms as clinically relevant tools for rapid cellular analysis and infectious disease diagnostics.