Pulse electrochemical synaptic transistor for supersensitive and ultrafast biosensors

High sensitivity and fast response are the figures of merit for benchmarking commercial sensors. Due to the advantages of intrinsic signal amplification, bionic ability, and mechanical flexibility, electrochemical transistors (ECTs) have recently gained increasing popularity in constructing various sensors. In the current work, we have proposed a pulse-driven synaptic ECT for supersensitive and ultrafast biosensors. By pulsing the presynaptic input (drain bias, V-D) and setting the modulation potential (gate bias) near transconductance intersection (V-G,V-i), the synaptic ECT-based pH sensor can achieve a record high sensitivity up to 124 mV pH(-1) (almost twice the Nernstian limit, 59.2 mV pH(-1)) and an ultrafast response time as low as 8.75 ms (7169 times faster than the potentiostatic sensors, 62.73 s). The proposed synaptic sensing strategy can effectively eliminate the transconductance fluctuation issue during the calibration process of the pH sensor and significantly reduce power consumption. Besides, the most sensitive working point at V-G,V-i has been elaborately figured out through a series of detailed mathematical derivations, which is of great significance to provide higher sensitivity with quasi-nonfluctuating amplification capability. The proposed electrochemical synaptic transistor paired with an optimized operating gate offers a new paradigm for standardizing and commercializing high-performance biosensors.