Ambipolar Fiber Amplifiers for Highly Sensitive Biosignal Detection

Biological signals are inherently weak and susceptible to noise, making in situ signal amplification critical for high-fidelity sensing. Electronic fibers offer unique advantages for conformal and scalable biointegration; however, fiber amplifiers are seldom reported due to the lack of suitable semiconducting materials that combine balanced ambipolar transport, scalable fiber fabrication, and high device performance. Herein, we report the first single-component ambipolar fiber platform based on a newly designed polymer, P(gTDPP-TQ), which combines balanced p- and n-type transport, low-cost synthesis, and continuous fiber fabrication. Fiber processing enhances molecular ordering and charge transport, yielding record-high µC* and g_m,norm among reported semiconducting fibers, enabling high-performance fiber amplifiers with a high voltage gain of up to 150 V V^-1 and low operating voltages down to 0.5 V. These fiber amplifiers enable high-fidelity electroencephalogram signal amplification over 20 times and sensitive cortisol sensing with a record-low detection limit of 3.7 fM. This work establishes a general ambipolar fiber platform for integrated bioelectronic amplification and sensing.