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

The 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 mu Vp-p at 10 Hz, which enables precision brain wave monitoring in a close correlation with signals obtained using a commercialized measurement system.