Fabrication, Characterization and Electrochemical Modeling of CNT Based Enzyme Field Effect Acetylcholine Biosensor

A carbon nanotube based enzyme field effect transistor has been fabricated and modeled for acetylcholine (ACh) detection, which finds varied applications in the field of biosensors and bioelectronics. The fabrication has been done using chemical solution process. The device consists of indium tin oxide coated glass plate as substrate, ZnO as bottom insulator, K-doped carbon nanotube as n-type channel, drain, and source regions, ZrO2 as top gate insulator and chitosan/nickel oxide (CH/NiO) nanocomposite as sensing membrane arranged from bottom to top respectively. Physical adsorption technique has been used for enzyme acetylcholine esterase (AChE) immobilization on the sensing membrane. The experimental results have shown good linearity from 0.01 to 0.2 mM concentration of ACh and a good sensitivity of 58 mV/decade at room temperature. Insignificant interference was observed with other clinical parameters. An electrochemical model of the fabricated device has been developed and then, simulated considering all the biological, chemical, and physical parameters of the device. The modeling and simulation results have shown good agreement with the experimental results.