Fabrication And Application In Synaptic Bionics Of Stretchable/Conformable Memory Devices

Neural synapse is one of the most basic units of learning and memory in biological brain.Its emulation is one important step towards artificial neural networks,for the development of the new-generation computer that requires catching the behavior of the complex,real-world environment.The conventional electronic synapses are composed of tens of transistors and capacitors,but large number of devices brings the problems in complexity,cost and power consumption.In contrast,recently developed two-and three-terminal devices have provided a promising opportunity for simplified electronic synapse design and improved integration.Therefore,using two-and three-terminal devices to achieve biomimetic bionics has been a research hotspot.Currently,most of the memristors have been fabricated with the brittle inorganic medium materials?like WO_x,Cu₂S,and Ag₂S?,or/and rigid substrates?like Si,Si/SiO₂,and glass?.And,most of the reported synaptic transistors have focused on the inorganic electronic devices,and have been constructed on the hard-planar glass and silicon substrates.However,synaptic transistor for biomedical applications,such as implanted treatment and electronic skin,must be elastic with good mechanical compatibility with the biological tissues.However,most of the two-and three-terminal devices have been fabricated with the brittle inorganic medium materials and will not likely work well for flexible electronics,especially for wearable devices.Compared with inorganic materials,organic materials bear advantages of mechanical flexibility,light-weight and low-cost applications.Until now,only a few research groups have shown the flexible bionic electron synapse.To enable artificial intelligence systems to meet the need of the rapidly growing of the wearable electronics market,the development and preparation of flexible/elastic bionic electron synapse is particularly important.To solve the above problem,in this paper,a stretchable/conformable memory device was developed by using the embedded electrode technology and using polydimethylsiloxane?PDMS?elastomer as a support layer,and study its application in synaptic bionics.The main contents are as follows:1.Based on the flexible embedded electrode technology,we successfully develop a stretchable/conformable two-terminal memristor by oxygen plasma and transfer alignment method.The stretchable/conformable synapse memristor by using a Ag nanoparticle-doped thermoplastic polyurethanes?TPU:Ag NPs?as medium layer and polydimethylsiloxane?PDMS?as supporting layer.The memristor can be well operated even at 60%strain,and can be well conformed onto the curved surfaces.These results indicate a feasible strategy to achieve wearable flexible artificial intelligence using organic materials.2.By comparing the performance of organic field-effect transistors?OFETs?with three different dielectric layers,it is concluded that the transistor with organsilicone as the dielectric layer exhibits the desirable synaptic behavior,including excitatory postsynaptic current?EPSC?and potentiation/depression characteristics.Through the Fourier transform infrared spectroscopy?FTIR?and KPFM method,the transfer curve hysteresis of the transistor is derived from the polarization of the polar functional group in our organsilicone dielectric.And the hysteresis window is also related to the morphology of the semiconductor film.These results lay the foundation for the preparation of conformable synaptic transistors.3.We fabricate a conformable synaptic transistor with organsilicone as the dielectric layer by using the embedded electrode technology,oxygen plasma and transfer alignment method.Adhered onto the curved surfaces,the synaptic transistor still can be well operated and remains the synaptic functions,which shows the potential to make wearable artificial intelligence and new-generation electronic devices.