Study On Artificial Synaptic Devices Based On Modified Micro/Nanopipets With Transient Asymmetric Ion Transport

At present,the efficiency of building circuits with silicon-based electronic components which were used to realize brain-like functions and process large amounts of data is not good enough.The conductivity of chemically designed synaptic device is analogous to the synaptic weight of biological synapse,and synaptic devices can have electrical signal transmission and processing behavior similar to biological synapse.So,they are suit to solve the problem.In the past ten years,ionic synaptic devices have been developed in a blowout manner.Researchers hope to further reduce their energy consumption,difficulty in fabrication,and achieve more brain-like functions.The modified conical glass pipet is an easy-to-prepare analytical sensing electrode that uses ion transport behavior to detect substances with low electrochemical activity,supplementing the deficiencies of traditional electrochemical sensors.The current response of the electrode has hysteresis characteristics under triangular wave scanning,and the closed current-voltage curve has memristive memristive characteristics.Therefore,the electrode can be constructed as a synaptic device theoretically without electron transferring,which is important for reducing power consumption.Among the modified conical glass pipet,the key(transient ion transmission)to regulating electrical signals has also begun to become the focus of the two fields in recent years,showing its huge research potential and broad development prospects.The main work of this paper is summarized as follows:(1)Poly-imidazole cationic brush was modified on the inner wall of a conical glass pipet with fully exposed silanol groups by the surface-initiated atom transfer radical polymerization method(PMMs),and preliminary characterization was carried out by scanning electron microscopy;The device was subjected to a memristive memristive test and triangular wave voltage is applied,then the closed current-voltage curve is obtained.It is found that the rectification ratio of the device increases firstly and then decreases with the increase of the electrolyte concentration.At the same time,rectification ratio decreases with the increase of the voltage scanning speed.Finally,combined with the knowledge of solid-state pore ion transport,the mechanism of the memristive characteristic of the curve is analyzed.(2)Compared with the COMSOL Multiphysics steady-state simulation model which is established by the idea of perforating in the membrane,we have established a more accurate transient simulation model with the geometric structure of the conical glass pipet and reasonable consideration of the real modified results.The ion current rectification phenomenon based on the three-layer theory was successfully demonstrated;According to the simulation results,the current value and the memristive region were smaller than the real results,it is speculated that the polarization behavior of the poly-imidazole cationic brush layer is an important factor to regulate device’s conductance.(3)The corresponding test square wave waveform was designed according to the experimental conditions,Then PMMs realized the simulation of the transition behavior from short-term plasticity,pulse frequency synaptic plasticity,short-term plasticity to long-term plasticity in brain-like function;Regulating the interior interval of pairedpulses,we obtains the retention time value of the device under specific conditions;the voltage amplitude and combination mode of the paired-pulses are adjusted to realize the directional change of synaptic weight,switching between long-term enhancement and long-term inhibition namely.At the same time,a result consistent with the theory was obtained.The greater the voltage amplitude,the greater the transformation of synaptic weight.