Biosignal Amplifiers Based on Low‐Noise Organic Transistors with Printed Electrodes

Abstract

AbstractThe monitoring of microvolt‐level biosignals such as electroencephalograms requires the application of low‐noise signal amplifier circuits, which, for single‐use cases, must be fabricated for disposability using low‐cost manufacturing techniques. One promising solution for the production of low‐cost amplifier circuits for digital biosensing is the emerging technology of low‐noise printed circuits. Here, a low‐noise‐electrode printing process for organic transistors that can carry out precision measurement of brain activity using a low‐noise organic amplifier is proposed. In the transistor fabrication process, Ag electrodes are processed via flat stamp parallel printing, and fine‐process optimization to minimize the charge‐trapping effect enables a three‐order reduction in transistor noise. The low‐noise transistors are used to produce an organic pseudo‐complementary metal‐oxide‐semiconductor amplifier with a small noise level of 2.2 µVp‐p at 10 Hz, which enables precision brain wave monitoring in a close correlation with signals obtained using a commercialized measurement system.