A CMOS integrated carbon nanotube biosensor with an actively controlled electrolyte electrochemical potential regulator

A CMOS integrated 32 × 32 sensor array chip for fully electric bio material detection is presented. The sensor principle is based on a carbon nanotube field effect transistor (CNT-FET). By using the CNT-FET's electrolyte gate characteristics, we successfully reduced the sensing noises through control sensors which are actively controlled by electrochemical potential regulator circuit. Because potential difference is imposed between electrolyte and the metal electrode by feedback mechanism, redox reaction which is fast enough to compensate the change of reference voltage can be achieved. This means conventional referencing material like Ag/AgCl or expensive porous Pt electrode can be replaced by normal metal electrodes which are compatible to CMOS fabrication technology. Proper operation of the chip is demonstrated by electrochemical experiments and actual sensor realization. The chip is fabricated on the basis of a 0.18µm CMOS process.