Carbon Nanotube Field-Effect Transistor Biosensors with High Signal-to-Noise Ratio using Alternating Current Measurement

Y. Yamamoto, Y. Ohno, K. Maehashi, and K. Matsumoto (Japan)


carbon nanotubes, fieldeffect transistors, noise, signalto noise ratio, alternating current, pH sensors, biosensors


We demonstrated the drastic improvement of sensitivity (signal-to-noise ratio) in carbon nanotube field-effect transistor (CNTFET) sensors. The alternating current (AC) measurement with a lock-in amplifier was adopted to suppress the fluctuations in drain current of CNTFETs without attenuating the signal level. The noise level of CNTFETs incubated in phosphate buffer solution was highly suppressed by the AC measurement. We also investigated the sensing operations of CNTFET pH sensors and biosensors using AC. Sensing performances in CNTFET sensors were dramatically improved. The signal-to-noise ratio of pH sensors measured by AC was six times higher than that by direct current (DC) measurement. Furthermore, a small amount of bovine serum albumin (BSA) of 250 pM was effectively detected by CNTFET biosensors using AC measurement.

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