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.