Monitoring extracellular K+ flux with a valinomycin-coated silicon nanowire field-effect transistor

► A silicon nanowire field-effect transistor coated with a polyvinyl chloride membrane containing valinomycin was used as a biosensor. ► Apparent association constants between valinomycin and Li+, Na+, K+, and Cs+ in Tris buffer solution were determined respectively. ► The nanowire-transistor biosensor was employed to detect the K+-efflux from live chromaffin cells. ► The nanowire-transistor biosensor is suitable for the applications in cellular recording investigations.