Interpretation of biosensing technology in cell-coupled silicon nanowire transistors via impedance spectra

Cell-coupled silicon nanowire field-effect transistor (SiNW FET) devices with p -type 1NW and 5NW were exploited to elucidate the effect on impedance spectra. Live observation of cells on the actual chips using a metallurgical microscope was also performed before each impedance measurement. The impedance sensing of 2D cell cultures using FET devices with a grounded solution showed that measurements result in more significant changes in | Z | and θ in the lower frequency range (100 Hz–1 kHz). Among the devices, the changes within 5NW in | Z | and θ in impedance spectra demonstrated the most changes. The changes constitute an initial increase in | Z | and decrease in θ one day after cell seeding, followed by a decrease in | Z | and increase in θ at day 3 the cell coverage on the surface of SiNW by negatively charged cell membrane. After cells have been detached, | Z | decreased while θ increased significantly in contrast to day 1. Owing to the hindrance of ions or negatively charged membrane of the coupled cells, the changes of carrier density within SiNW correspond to the signals in impedance spectra and can be used to probe cell condition during the growth.