C. Becker-Freyseng, and P. Fromherz
We report on the quantized response of a field-effect transistor to molecular ion channels in a biomembrane. HEK293-type cells overexpressing the Shaker B potassium channel were cultured on a silicon chip. An enhanced noise of the transistor is observed when the ion channels are activated. The analysis of the fluctuations in terms of binomial statistics identifies voltage quanta of about 1 µV on the gate. They are attributed to the channel currents that affect the gate voltage according to the Green’s function of the cell-chip junction.
Fig. 3. Relation between transistor voltage and pipette current. (a) Ensemble average of the transistor voltage versus ensemble average of the pipette current for intracellular voltages 20 mV and 0 mV. The data are fitted by a linear relation with a slope 0.18 MOhm. (b) Ensemble variance of the transistor voltage versus ensemble variance of the pipette current. The bars indicate the standard error of the bins. The data are fitted by a linear relation with a slope 0.273 MOhm² and a background of 1100 µV².
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