Acetylcholine biosensors based on layer-by-layer self-assembled polymer/nanoparticle ion-sensitive field-effect transistors

In this paper, the fabrication and characterization of acetylcholine biosensors based on nano self-assembled ion-sensitive field-effect transistors (ISFETs) are demonstrated. The fabrication is implemented with a very low-cost layer-by-layer nano self-assembly technique. The self-assembled polyaniline thin films work as the semiconducting channel material, while silicon dioxide (SiO2) nanoparticle thin films serve as the gate dielectric material. Both the silicon wafer and flexible plastic transparency have been applied as the substrate materials. A polyaniline ISFET on silicon wafer operates at a low-voltage range and has a mobility of 1.49 cm2/V s. Acetylcholine in a concentration as low as 1 μM could be detected with this sensor. A polyaniline ISFET on plastic substrate could detect acetylcholine concentration down to 10 μM. The results presented in this paper suggest a route to fabricate inexpensive and flexible ion-sensitive field-effect transistors for biosensing applications.