Noise Properties of Incubation-Type Planar Ion Channel Biosensor

Current noise and its power spectrum have been measured by an incubation-type planar ion channel biosensor. The dominant noise sources are classified into (i) current noise induced by head stage preamplifier input voltage noise, (ii) thermal noise, and (iii) excess noise. The spectral density and variance of these noises are formulated in the general form using an equivalent circuit. The observed noise in the device has been explained by the excess noise, which depends on 1/ f and originates primarily from the current passing through the cleft between the cell membrane and the substrate surface.