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The hierarchical structure of the biological visual system enables multilevel features of sensory stimuli to be pre-extracted before being transmitted to the nerve center, rendering the remarkable ability to perceive, filter, categorize, and identify targets in complex environments. However, it is a challenge to resemble such extraction capability with respect to spatial features in a neuromorphic visual system. In this Letter, we propose an indium-gallium-zinc-oxide synaptic transistor-based Fourier neuromorphic visual system for image style classifying. The images are transformed into the frequency domain through an optic Fourier system, greatly reducing energy and time dissipation in comparison with numerical computation. Then, the transformed information is coded into spike trains, which are nonlinearly filtered by synaptic transistors. The energy consumption for this filtering process is estimated to be ∼1.28 nJ/pixel. The features of drawing style could be enhanced through the filtering process, which facilitates the followed pattern recognition. The recognition accuracy in classifying stylized images is significantly improved to 92% through such Fourier transform and filtering process. This work would be of profound implications for advancing neuromorphic visual system with Fourier optics enhanced feature extraction capabilities. [ABSTRACT FROM AUTHOR]

In recent years, the rapid increase in the data volume to be processed has led to urgent requirements for highly efficient computing paradigms. Brain-like computing that mimics the way the biological brain processes information has attracted growing interest due to extremely high energy efficiency. Particularly, dynamics play an essential role in neural spike information processing. Here, we offer a brief review and perspective in the field of electrolyte-gated neuromorphic transistors for brain-like dynamic computing. We first introduce the biological foundation of dynamic neural functions. Then dynamic synaptic plasticity, dynamic dendritic integration, dynamic neural functions, and bio-inspired somatosensory systems realized based on the electrolyte-gated neuromorphic transistors are presented. At last, conclusions and perspectives are given. [ABSTRACT FROM AUTHOR]

Fear neural circuits can recognize precisely threatening stimuli and enable the early-warning for the individual in the real world. In this regard, implementation of fear neural circuits functions by neuromorphic devices could potentially improve the intelligent adaptability and cognition of humanoid robots. Here, an artificial fear neural circuit is proposed, which consists of a noise triboelectric nanogenerator (N-TENG) and an amorphous indium gallium zinc oxide based photoelectronic neuromorphic transistor (IGZO-PNT). Such an artificial fear neural circuit collects sound wave and light signals from the N-TENG and a-IGZO channel, respectively, converts these signals to electrical signals and integrates them into excitatory postsynaptic currents by the IGZO-PNT. The innate-fear and learned-fear behaviors are emulated by our artificial fear neural circuit. Furthermore, as a proof of concept, the escape behavior after fear triggered is realized by using a vibrator. Our biomimetic design can promote the developments of next-generation photoelectronic neuromorphic systems and humanoid robots. [ABSTRACT FROM AUTHOR]

Artificial leaky integrate-and-fire (LIF) neurons have attracted significant attention for building brain-like computing and neuromorphic systems. However, previous artificial LIF neurons have primarily focused on implementing integrate-and-fire function, and the function of dendritic modulation has rarely been reported. In this Letter, a tunable artificial LIF neuron based on an IGZO electric-double-layer (EDL) transistor and a TaOx memristor is fabricated, and dendritic modulation is investigated. An IGZO-based EDL transistor with a modulatory terminal is used to realize dendritic nonlinear integration and filtering capability, as well as the tunable neural excitability. An Ag/TaOx/ITO threshold switching memristor mimics the all-or-nothing spiking and threshold switching of the soma. By incorporating these two components in a customized way, such artificial LIF neuron can emulate the key function of biological neuron with rich computational flexibility. Our artificial LIF neurons with rich nonlinear dynamics have great potential to perform more complex tasks in future spiking neuromorphic systems. [ABSTRACT FROM AUTHOR]

Synaptic plasticity divided into long-term and short-term categories is regarded as the origin of memory and learning, which also inspires the construction of neuromorphic systems. However, it is difficult to mimic the two behaviors monolithically, which is due to the lack of time-tailoring approaches for a certain synaptic device. In this Letter, indium-gallium-zinc-oxide (IGZO) nanofiber-based photoelectric transistors are proposed for realizing tunable photoelectric synaptic plasticity by the indium composition ratio. Notably, short-term plasticity to long-term plasticity transition can be realized by increasing the ratio of indium in the IGZO channel layer. The spatiotemporal dynamic logic and low energy consumption (<100 fJ/spike) are obtained in devices with low indium ratio. Moreover, the symmetric spike-timing-dependent plasticity is achieved by exploiting customized light and electric pulse schemes. Photoelectric long-term plasticity, multi-level characteristics, and high recognition accuracy (93.5%) are emulated in devices with high indium ratio. Our results indicate that such a composition ratio modulated method could enrich the applications of IGZO nanofiber neuromorphic transistors toward the photoelectric neuromorphic systems. [ABSTRACT FROM AUTHOR]

Hardware implementation of Bienenstock–Cooper–Munro (BCM) learning rules would be of great implications toward artificial intelligent systems. In this work, amorphous indium gallium zinc oxide (a-IGZO)-based photoelectronic neuromorphic transistors were proposed for mimicking BCM learning rules. A SiO2 electrolyte film with a large electric-double-layer capacitance ($0.33~\mu \text{F}$ /cm2) was used for the gate dielectric film. Light induced short-term synaptic plasticity can be mimicked by such device, including excitatory postsynaptic current (EPSC), paired-pulse facilitation (PPF), and high-pass temporal filtering. More importantly, BCM learning rules are realized based on this photoelectronic neuromorphic transistor. These results would provide a step forward the development of photoelectronic neuromorphic systems with sophisticated learning rules. [ABSTRACT FROM AUTHOR]

The human brain that relies on neural networks communicated by spikes is featured with ultralow energy consumption, which is more robust and adaptive than any digital system. Inspired by the spiking framework of the brain, spike-based neuromorphic systems have recently inspired intensive attention. Therefore, neuromorphic devices with spike-based synaptic functions are considered as the first step toward this aim. Photoelectric neuromorphic devices are promising candidates for spike-based synaptic devices with low latency, broad bandwidth, and superior parallelism. Here, the indium-gallium-zinc-oxide-based photoelectric neuromorphic transistors are fabricated for Morse coding based on spike processing, 405-nm light spikes are used as synaptic inputs, and some essential synaptic plasticity, including excitatory postsynaptic current, short-term plasticity, and high-pass filtering, can be mimicked. More interestingly, Morse codes encoded by light spikes are decoded using our devices and translated into amplitudes. Furthermore, such devices are compatible with standard integrated processes suitable for large-scale integrated neuromorphic systems. [ABSTRACT FROM AUTHOR]

The pain perception system is of great importance for the human body to perceive noxious stimuli in external environment and make an appropriate reaction. Therefore, the hardware realization of nociceptors using emerging solid‐state device is of great importance toward the next‐generation intelligent electronic devices. However, at present, the pain recognition with threshold regulation is still very lacking by using the solid‐state device. Herein, a novel pain‐perceptual device based on organic–inorganic hybrid MoS2 transistor is fabricated by using polyvinyl alcohol‐based electrolyte. The key characteristics of pain perception, such as threshold, sensitization, and desensitization behaviors, are realized in the organic–inorganic hybrid neuromorphic transistor based on the unique ion migration mechanism. Most importantly, the device exhibits a clear transition from pain to fear recognition through the Pavlovian training. These results provide a promising strategy to the next generation of bio‐inspired electronic devices, smart healthcare, cognitive electronics, etc. [ABSTRACT FROM AUTHOR]

We report a high-performance transparent amorphous indium gallium zinc oxide thin-film transistor (a-IGZO TFT) gated by atomic layer deposition (ALD)-deposited HfAlOx. Through a postfabrication annealing optimization process, the total trap density of the device can be reduced in two orders of magnitudes. The subthreshold swing (SS) reaches an ultralow level of 62.29 mV/dec due to the low defect states. A large $I_{\text{ON}}/I_{\text{OFF}}$ and a high mobility of 2.76 $\times 10^{{9}}$ and 18.94 cm2/ $\text{V}\cdot \text{s}$ can be achieved, respectively. In addition, the devices exhibit good stability in terms of positive bias stress, thermal, and aging tests. The defect optimization process has been verified by the X-ray photoelectron spectroscopy analysis. Finally, a resistor-loaded inverter was constructed, which showed ideal swing characteristics and its voltage gain was as high as 39 at 7 V. These results indicate such a-IGZO TFT is of great potential for the emerging electronics, large-area display, and other low-power electronics. [ABSTRACT FROM AUTHOR]

Photoexcited corneal nociceptor (PCN) can recognize the noxious light stimulus and generate/transmit pain signals to the central nervous system, enabling the early‐warning and/or risk avoidance for the individual. Futhermore, central pain‐modulation can enhance pain or relieve pain, which greatly assists human adaptation to environments. Emulation of PCN and central pain‐modulation by neuromorphic devices will greatly improve the intelligence and adaptation of humanoid robots and artificial eyes in the real world. Here, amorphous indium‐gallium‐zinc‐oxide (a‐IGZO) based photoelectric neuromorphic transistors are fabricated with chitosan/graphene oxide nanocomposite electrolyte membranes as the gate dielectrics as well as the mechanical supports. PCN characteristics, including threshold, no‐adaptation, relaxation, allodynia and hyperalgesia, can be mimicked by the device and are attributed to the persistent photoconductivity performance of the IGZO channel. More importantly, central pain‐modulation containing central sensitization and analgesic effect is also successfully emulated by optoelectronic synergistic modulation. The results provide an important step toward to endow humanoid robots with visual intelligence and propel the development of neuromorphic perceptual systems. [ABSTRACT FROM AUTHOR]

Humans can clearly perceive surroundings efficiently while consuming little energy because of human intelligence and powerful vision system. Thus, it has been a long‐sought dream for human beings to build such an energy‐efficient artificial intelligent vision system with emerging devices. Unfortunately, a wearable optoelectronic device for visual nociceptor systems, regarded as a key bionic function to protect the vision, remains to be developed so far. Herein, using the vertical coplanar‐multiterminal flexible transient photogating transistor network with a 3 nm ultrashort channel, a wearable artificial vision system with painful‐perceptual abilities is successfully demonstrated for flexible electronic‐skin (e‐skin) applications. The device not only has the ability of ultrafast transient physical disappearance of only 60 s for information security but also establishes a flexible optical in‐sensor visual nociceptor (ISVN) e‐skin. The optical transition from short‐time memory to long‐time memory of visual memory is educed by a strong photogating effect, and the higher‐level‐graded optical painful alarm‐sensing system is also demonstrated by this flexible artificial e‐skin. Moreover, the proposed devices will achieve painful light sensitization under different spatiotemporal color patterns to avoid external secondary injuries. It provides a good opportunity for future intelligent e‐skin taking advantage of its intriguing visual pain‐perceptual abilities. [ABSTRACT FROM AUTHOR]

Flexible neuromorphic devices are highly desirable for emerging perception and sensing systems. Here, multiterminal neuromorphic devices based on freestanding dual-gate MoS2 transistors on freestanding proton-conducting chitosan membranes are proposed. The chitosan membranes are simultaneously used as the dielectrics and substrates. By replicating the surface of silicon substrate, the roughness of chitosan substrate is successfully reduced from 11 to 1.7 nm. Besides, the membranes show a large specific in-plane electric-double-layer capacitance of 1.3 μF/cm2 at 1.0 Hz when the interelectrode space is 100 μm. The dual-gate MoS2 transistors exhibit high mechanical stability and electrical performance on flexible chitosan membranes. Some important synaptic functions, such as paired-pulse facilitation, and tunable high pass filter, are successfully emulated. Furthermore, spatiotemporal dynamic correlation is also experimentally demonstrated. Our results will greatly enrich the intension of 2-D flexible electronics and neuromorphic perception and sensing systems. [ABSTRACT FROM AUTHOR]

Synaptic plasticity is a basic characteristic of synapses and plays an important role in the computation, learning and memory of human brain. Metaplasticity is a higher-order form of synaptic plasticity, which regulates the ability of synapses to generate synaptic plasticity and has a great regulating effect on later learning, memory and coping behaviors. At present, there are rarely reports on the emulation of synaptic metaplasticity in synaptic transistor. In this article, flexible dual-gate indium-zinc-oxide neuromorphic devices on freestanding solid-state proton conducting chitosan electrolyte membrane are designed for metaplasticity emulation. The key synaptic plasticity functions including excitatory postsynaptic current, synaptic paired-pulse response and synaptic pulse train response can be effectively regulated by the priming pulse stimuli. Besides, configurable synaptic depression and synaptic potentiation effect can be realized in such device. These results can expand the potential applications of the multi-terminal electrolyte-gated oxide transistors for flexible dynamic neuromorphic platforms. [ABSTRACT FROM AUTHOR]

Emulation of synaptic function by ionic/electronic hybrid device is crucial for brain-like computing and neuromorphic systems. Electric-double-layer (EDL) transistors with proton conducting electrolytes as the gate dielectrics provide a prospective approach for such application. Here, artificial synapses based on indium-tungsten-oxide (IWO)-based EDL transistors are proposed, and some important synaptic functions (excitatory post-synaptic current, paired-pulse facilitation, filtering) are emulated. Two types of spike-timing-dependent plasticity (Hebbian STDP and anti-Hebbian STDP) learning rules and multistore memory (sensory memory, short-term memory, and long-term memory) are also mimicked. At last, classical conditioning is successfully demonstrated. Our results indicate that IWO-based neuromorphic transistors are interesting for neuromorphic applications. [ABSTRACT FROM AUTHOR]

Neuromorphic devices are of great significance for next generation energy-efficient brain-like computing and perception. Oxide-based photoelectric neuromorphic transistors are very promising due to the proton-related electric-double-layer (EDL) effect and persistent photoconductivity behavior. In this study, indium-gallium-zinc-oxide (IGZO)-based photoelectric neuromorphic thin-film transistors (TFTs) with tunable synaptic plasticity are proposed. Some important synaptic functions, such as excitatory postsynaptic current, multipulse facilitation, and long-term plasticity, can be effectively tuned by the photoelectric synergistic modulation. More importantly, under the photoelectric synergistic modulation, the temporary short-term memory can be converted into permanent long-term memory. And the voltage coordinated modulation can enhance the image in the pixel and the ability of real-time data processing of the input visual information. Our results are very important for the development of photoelectric neuromorphic devices with configurable dynamic functions. [ABSTRACT FROM AUTHOR]

We developed a bionic multiterminal, tunable ion gel-gated synaptic transistor to emulate reflex actions. Our device is innovatively designed with multi-presynaptic and modulatory terminals, which emulates the dendrites and descending pathways from the brain. These structures enable simultaneous processing of multiple signals from diverse sensory modalities and active modulation as enhancement or suppression of responses. The device emulates basic synaptic functions including current (EPSC) and high-pass filtering, while being sensitive to the amplitude, frequency, and duration of external stimuli. To demonstrate its potential applications, we emulate the eyeblink reflex in different scenarios. Results indicate that our synaptic transistor is well capable of multi-stimuli sensing under modulations, which is a crucial ability for artificial systems to perceive and adapt to more complex environments. [ABSTRACT FROM AUTHOR]

A nociceptor is a type of sensory receptor with the ability to perceive noxious stimuli, which is very important for the survival and health of organisms. Several neuromorphic devices have been proposed to emulate this sensory receptor. The basic pain perception functions of a nociceptor can be emulated. However, those artificial nociceptors lack functional tunability and intelligent adaptability. Here, freestanding oxide-based neuromorphic transistors with dual-gate structures were fabricated on proton-conducting electrolyte membranes and used for flexible artificial nociceptor emulation. Such a freestanding biomimetic device can not only capture the pain perception functions to peripheral inputs. What is more, the modulation of pain sensitivity can be emulated in this device by the voltage applied on the second gate electrode. Our artificial nociceptors open a new avenue in the design of an artificial sensory system with sensory alarm function and intelligent adaptability. [ABSTRACT FROM AUTHOR]

Capacitively coupled neuromorphic system is very promising for spiking dynamic computing because of the inherent advantages of low static power and large fan-out. Here, flexible multigate indium–gallium–zinc–oxide (IGZO) Schottky thin-film transistors (TFTs) with configurable neuromorphic functions are investigated. The channel layer can be effectively modulated by the multigate terminals through electric-double-layer coupling effect. Plastic modulation of Schottky barrier is also demonstrated, which is highly desirable for dynamic synaptic weight modulation. Furthermore, configurable spiking dynamic functions, such as paired-pulse facilitation (PPF) and high-frequency spike filter, are also emulated in such flexible oxide-based Schottky neuromorphic device. [ABSTRACT FROM AUTHOR]

Freestanding thin-film transistors (TFTs) with multiple in-plane gates could meet increasing demands of mechanical flexibility and multifunctional integration. In this letter, freestanding flexible indium-zinc-oxide based TFTs with multi-gate structure and high electrical performance were reported. No obviously electrical degradation is observed under various mechanical stimuli due to the mechanical reinforcement effect of graphene oxide. Multifunctional operations including AND, OR gates and a Schmitt trigger are successfully demonstrated. More importantly, OR logic to AND logic transformation is also realized by a third modulatory terminal. Such freestanding TFTs are promising candidates for next-generation flexible smart electronic systems. [ABSTRACT FROM AUTHOR]

Neuromorphic computing, that is expected to be implemented with emerging synaptic devices, may overcome the inherent efficiency bottleneck in conventional digital computers. In this article, low-temperature processed indium-gallium-zinc-oxide (FGST) based floating-gate synaptic transistors with Al2O3/ITO/Al2O3 gate dielectric stacks are proposed for neuromorphic computing. The synaptic weight is stored as the channel conductance (G) of the floating-gate synaptic transistor (FGST). Negative/positive electrical pulse stimuli are applied on the bottom gate electrode of the synaptic transistor to facilitate/depress the synaptic weight, respectively. The operation mechanism of such neuromorphic devices is discussed based on the electron direct tunneling. Furthermore, the retention of the synaptic weight and the device endurance characteristics of the synaptic transistors are also investigated. In addition, in simulations with the measured device properties, an artificial neural network consisting of such floating-gate synaptic transistors shows a high classification accuracy of 95.7% for small digits dataset. These results may provide insight into potential applications of the floating-gate oxide-based synaptic transistors for artificial neural networks. [ABSTRACT FROM AUTHOR]

Interfacial ion/electron coupling and electrochemical doping are of great importance for the electrochemical sensors and the neuromorphic system. Schmitt triggers with adjustable hysteresis can be used as a basic unit for the neuromorphic system. In this letter, we demonstrated a simple low-voltage Schmitt trigger with one indium–tungsten-oxide homojunction electric-double-layer thin-film transistor. Adjustable hysteresis is observed due to the dynamic modulation of mobile proton in the electrolyte gate dielectric. The ion/electron hybrid Schmitt triggers with adjustable hysteresis window are very interesting for electrochemical sensors and neuromorphic computation. [ABSTRACT FROM AUTHOR]

Indium–gallium–zinc-oxide (IGZO) photoelectric neuromorphic transistors with low-temperature atomic layer deposited Al2O3 gate dielectrics are fabricated. Dual-functional long-term plasticity, including long-term depression (LTD) and long-term potentiation (LTP), is emulated. The emulation of LTD is achieved by applying high-electrical pulse trains on the gate electrode. The LTP emulation is realized by applying light pulse trains on the IGZO channel layer. The operation mechanisms of the LTD and the LTP are discussed based on the electron/hole trapping in the Al2O3 gate dielectrics and the persistent photoconductivity of the IGZO channel layer. [ABSTRACT FROM AUTHOR]

In order to obtain higher humidity sensitivity, shorter response/recover time, and lower energy consumption, we investigate the dynamic humidity sensing characteristics of indium–zinc-oxide (IZO)-based synaptic transistors with graphene oxide/chitosan composite electrolyte films as the gate dielectrics. Here, the short-term synaptic plasticity parameters, such as excitatory post-synaptic current, paired-pulse facilitation index, and high-pass filtering coefficient, were used for quantitative characterization of the relative humidity. The spiking humidity response time and energy consumption of such synaptic transistors are estimated to be 30 ms and 2.2 nJ, respectively. At the same time, a model based on the humidity-dependent proton gating and the adsorption of water molecules at the IZO channel surface is proposed. [ABSTRACT FROM AUTHOR]

Silent synapses play an important role in synaptic plasticity and the nervous system development. In this letter, indium–gallium–zinc–oxide (IGZO) Schottky electric-double-layer transistors were proposed for silent synapse conversion emulation. Silent to active conversion of such neuromorphic devices was realized by applying voltage pulses on the gate electrode of the synaptic transistor. In addition, some important synaptic behaviors, such as paired-pulse facilitation and dynamic high-pass filtering, were also emulated in the IGZO-based Schottky synaptic transistor after electric pulse activation. [ABSTRACT FROM AUTHOR]

Temporal filtering supports a variety of neural coding and signal processing in our brain, such as sensory adaptation, dynamic input compression, and selective communication. In this letter, neuromorphic devices and circuits based on indium-zinc-oxide (IZO) electric-double-layer (EDL) transistors are proposed for biological filtering emulation. For the first time, biological band-pass filtering is emulated by a simple circuit with only two IZO EDL transistors. The resonant frequency can be modulated by the device and circuit parameters. Our results demonstrate the potential application of oxide-based EDL transistors in neuromorphic systems and brain-like computation. [ABSTRACT FROM AUTHOR]

Inspired by the neocortex of the human brain, neuromorphic systems are favorable for processing a variety of complex tasks, such as recognition, prediction, and optimization. To build such an intelligent system, neuromorphic devices are in high demand. Here, photoelectric neuromorphic devices based on pulse light-stimulated low-voltage indium?gallium?zinc-oxide electric-double-layer transistors were investigated. Such devices can mimic some important synaptic behaviors, such as excitatory post-synaptic potentials, paired-pulse facilitation, and long-term plasticity in the form of photonic excitatory post-synaptic potentials. At last, depression mode to potentiation mode transition was also demonstrated by gate voltage modulation. Our photoelectric neuromorphic devices are interesting for photonic neuromorphic systems. [ABSTRACT FROM PUBLISHER]

Oxide-based electric-double-layer (EDL) transistors were reported to be promising candidates for artificial synapses/neurons. In this letter, a behavioral model of neuromorphic device based on a proton conducting electrolyte laterally coupled oxide-based EDL transistor is developed by integrating charge accumulation/relaxation processes and the classical field-effect transistor characteristics. The device model can reproduce both dc behaviors and the dynamic synaptic functions. Some complex neuromorphic functions, such as neural network classifications can be realized by introducing such device model into circuit simulations. Our results are interesting for the hardware implementation of neuromorphic systems. [ABSTRACT FROM AUTHOR]

Quick and accurate detection of dopamine (DA) is of great significance for routine analysis and biomedical diagnosis. Here, low-voltage indium-zinc-oxide (IZO) homojunction electric-double-layer (EDL) transistors using nanogranular SiO2 electrolytes as the gate dielectrics are proposed for DA detection. A DA detection limit of 0.1 nM with good selectivity is obtained at a low voltage of 0.8 V. The DA sensing mechanism can be attributed to the modulation of surface potential of the indium-tin-oxide (ITO) gate electrode by preferential binding of DA molecule to phenylboronic acid. Such low-voltage oxide-based EDL transistors have potential application in biochemical sensors. [ABSTRACT FROM PUBLISHER]

A low-voltage depletion-load inverter consisting of oxide transistors gated by nanogranular phosphorosilicate glass electrolytes has been fabricated. An indium-zinc–oxide electric-double-layer (EDL) transistor shows a threshold voltage ( V\mathrm {th} ) of approximately −0.1 V and acts as a load. An indium-gallium–zinc-oxide EDL transistor shows a V\mathrm {th} of $\sim 0.3$ V and acts as a driver. The depletion-load inverter shows a high voltage gain of $>40$ and a narrow transition width of $<0.2$ V at low supply voltage of 2 V. The proposed low-voltage inverter may find potential applications in portable electronics and biosensors. [ABSTRACT FROM PUBLISHER]

Artificial synaptic devices have attracted a broad interest for hardware implementation of brain-inspired neuromorphic systems. In this letter, a short-term plasticity simulation in an indium–gallium–zinc oxide (IGZO) electric-double-layer (EDL) transistor is investigated. For synaptic facilitation and depression function emulation, three-terminal EDL transistor is reduced to a two-terminal synaptic device with two modified connection schemes. Furthermore, high-pass and low-pass filtering characteristics are also successfully emulated not only for fixed-rate spike train but also for Poisson-like spike train. Our results suggest that IGZO-based EDL transistors operated in two terminal mode can be used as the building blocks for brain-like chips and neuromorphic systems. [ABSTRACT FROM PUBLISHER]

Artificial synapse is the key element for neuromorphic systems. Recently, synaptic transistors have been proposed and investigated, but physical understanding of such synaptic devices based on ion/electron electrostatic coupling effect remains unknown. Here, laterally coupled InGaZnO4 electric-double-layer synaptic transistors were numerically simulated. An ion drift-diffusion model is employed to describe the laterally capacitive coupling of the proton conducting electrolyte. Important synaptic behaviors, such as excitatory postsynaptic current and paired-pulse facilitation, are mimicked by the transient solution. InGaZnO4 synaptic device exhibits an extremely low-power consumption of $\sim 0.2$ pJ/spike. Our simulation results are interesting for energy-efficient synaptic electronics and neuromorphic systems. [ABSTRACT FROM PUBLISHER]

Flexible low-voltage indium-gallium-zinc-oxide (IGZO) electric-double-layer transistors are fabricated on polyethylene terephthalate substrates at room temperature and proposed for energy-efficient artificial synapse application. The IGZO channel conductance and the gate voltage pulse are regarded as synaptic weight and synaptic spike, respectively. The energy consumption of our IGZO synaptic transistor is estimated to be as low as $\sim 0.23$ pJ/spike. Short-term synaptic plasticity and high-pass filtering behaviors are also mimicked in an individual IGZO synaptic transistor. [ABSTRACT FROM PUBLISHER]

Laterally coupled indium-zinc-oxide electric-double-layer (EDL) transistors gated by solution-processed sodium alginate electrolyte films are self-assembled on glass substrates. Due to the strong EDL effect, a low-operation voltage of 1.5 V, a high-current ON/OFF ratio of \sim 3.1\times 10^6 and a high-electron mobility of $\sim 8.8$ cm ^{2} /Vs are obtained. Furthermore, AND logic operation is demonstrated when two in-plane gate electrodes are used as the input terminals. Such low-voltage laterally coupled oxide EDL transistors have potential applications in portable biosensors and synaptic electronics. [ABSTRACT FROM AUTHOR]

Free-standing chitosan membranes with high proton conductivity are prepared by a simple coating-peeling process. Laterally coupled flexible indium–zinc oxide electric-double-layer transistors with dual in-plane gates are fabricated on such chitosan membranes for the first time. The operation voltage, subthreshold swing, and field-effect mobility are estimated to be 1.0 V, 119 mV/decade, and 1.2 cm \(^{\mathrm {\mathbf {2}}}\) /V \(\cdot \) s, respectively. Finally, “AND” logic operation is experimentally demonstrated with two in-plane gates as the input terminals. Such free-standing laterally coupled flexible transistors have potential applications in biosensors and biocompatible electronics. [ABSTRACT FROM PUBLISHER]

Electronic implementation of biological synapses with essential plasticity and computing functions has been paid world-wide attentions. Here, laterally coupled indium-zinc oxide (IZO)-based synaptic transistors gated by solution-processed sodium alginate proton conducting electrolyte films are fabricated at room temperature. Synaptic behaviors and functions, including paired-pulse facilitation, high-pass filtering, and dendritic integration, are experimentally mimicked. Proton lateral migration-induced electric-double-layer electrostatic modulation is of great importance for such emulation. Such IZO-based synaptic transistors provide an interesting approach for synaptic electronics and neuromorphic systems. [ABSTRACT FROM AUTHOR]

Classical conditioning, a fundamental property in associative learning, has aroused a wide range of interests in neuromorphic engineering. Here, junctionless indium–zinc–oxide (IZO)-based electric-double-layer transistors gated by nanogranular SiO2 proton conducting electrolyte films are proposed to mimic such behavior. Proton-related electrochemical doping can result in evident oxygen vacancy in IZO channel layer, which is demonstrated by X-ray photoelectron spectroscopy measurements. After such electrochemical forming in half part of the IZO channel, conditioning response can be observed by gate-pulse training process. [ABSTRACT FROM AUTHOR]

Indium-zinc-oxide (IZO)-based electric double layer (EDL) transistors gated by solution-processed chitosan electrolyte films are fabricated on glass substrates and used for mimicking synaptic plasticity. The conductance of the self-assembled IZO channel tuned by the proton electrostatic modulation and electrochemical doping is regarded as the synaptic weight. Synaptic behaviors like paired-pulse facilitation and long-term potentiation are mimicked in the chitosan-gated IZO-based EDL transistor. Our results suggest that gate pulse amplitude and number have great influence on the synaptic plasticity transition. [ABSTRACT FROM PUBLISHER]

Short-term memory (STM) is a temporary potentiation of neural connections, and it can be transformed to long-term memory (LTM) through the process of rehearsal and meaningful association. Here, indium-zinc oxide (IZO)-based synaptic transistors gated by SiO2-based proton conducting electrolyte films were fabricated. STM behavior is demonstrated by paired-pulse facilitation experiment. STM to LTM transition is realized by increasing the pulse amplitude or pulse number. Interfacial electrostatic modulation and electrochemical doping of IZO channel by mobile proton play an important role for such memory behavior and memory transition. [ABSTRACT FROM PUBLISHER]

In the human brain, synapses are the crucial connective parts between neurons, which endow neurons with significant computational abilities. Here, indium-zinc-oxide (IZO) based flexible synaptic transistors are fabricated on a plastic substrate by a simple self-assembly method. Proton conducting phosphorus-doped nanogranular SiO2 electrolyte is used as the gate dielectric. Excitatory postsynaptic current, paired-pulse facilitation, and long-term memory are mimicked in the flexible artificial synapses. Such IZO-based flexible electronic synapses are promising for building neuromorphic systems. [ABSTRACT FROM AUTHOR]

In-plane-gate transparent \SnO2 nanowire transistors gated by \SnO2-based solid electrolytes are fabricated on glass substrate at room temperature. Low-voltage (1.0 V) operation of such device is realized due to the large electric-double-layer capacitance of 0.75 \mu\F/cm^2 at 20 Hz. The subthreshold slope, current on/off ratio, and field-effect mobility of the in-plane-gate transparent nanowire transistors are estimated to be 92 mV/decade, > \10^5, and 106.8 \cm^2/\V \cdot \s, respectively. Such low-voltage in-plane-gate transparent nanowire transistors are promising for portable invisible sensors. [ABSTRACT FROM PUBLISHER]

Transparent \SnO2 nanowire electric-double-layer (EDL) transistors with different antimony (Sb) doping levels are fabricated on transparent conducting glass substrates. The threshold voltage (Vth) can be effectively modulated by in situ Sb doping. Both enhancement mode and depletion mode are realized, and the Vth shift of the nanowire EDL transistors is estimated to be 0.41 V. All nanowire EDL transistors show good electrical characteristics with a high field-effect mobility (>\100\ \cm^2/\V\cdot\s), a high drain-current on/off ratio (>\8 \times \10^4), and a small subthreshold slope (< 200 mV/dec). These transparent nanowire EDL transistors are promising for “see- through” nanoscale sensors. [ABSTRACT FROM AUTHOR]

A size controllable graphene micro/nanogap fabrication method using micro/nanowire as mask is presented. The gap dimension can be adjusted by the diameter of the mask wire. As a typical application, copper phthalocyanine (CuPc) film organic field-effect transistors (OFETs) were fabricated with the graphene micro/nanogap bottom electrodes. The ultrathin thickness of the graphene, combined with its good compatibility with organic semiconductors, and high electrical conductivity produced high-performance CuPc film device with mobility at 0.053 cm2/Vs and on/off ratio at 105, showing promising potential in low-cost and light-weight electronics. [ABSTRACT FROM AUTHOR]

Fully transparent \In2\O3 nanowire transistors gated by LiCl-incorporated \SiO2-based solid electrolytes are fabricated on glass substrates at room temperature. Ultralow-voltage (0.4 V) operation of such a device is realized due to the extremely large electric-double-layer (EDL) capacitance (8.93 \mu\F/cm^2 at 20 Hz) of the composite solid electrolyte. The subthreshold slope and equivalent field-effect mobility of the transparent nanowire EDL transistors are estimated to be 70 mV/dec and 739.7 \cm^2/\V\cdot\s, respectively. Such ultralow-voltage transparent nanowire transistors are promising for portable invisible sensors. [ABSTRACT FROM PUBLISHER]

As promising biochemical sensors, ion-sensitive field-effect transistors (ISFETs) are used widely in the growing field of biochemical sensing applications. Recently, a new type of field-effect transistor gated by ionic electrolytes has attracted intense attention due to the extremely strong electric-double-layer (EDL) gating effect. In such devices, the carrier density of the semiconductor channel can be effectively modulated by an ion-induced EDL capacitance at the semiconductor/electrolyte interface. With advantages of large specific capacitance, low operating voltage and sensitive interfacial properties, various EDL-based transistor (EDLT) devices have been developed for ultrasensitive portable sensing applications. In this article, we will review the recent progress of EDLT-based biochemical sensors. Starting with a brief introduction of the concepts of EDL capacitance and EDLT, we describe the material compositions and the working principle of EDLT devices. Moreover, the biochemical sensing performances of several important EDLTs are discussed in detail, including organic-based EDLTs, oxide-based EDLTs, nanomaterial-based EDLTs and neuromorphic EDLTs. Finally, the main challenges and development prospects of EDLT-based biochemical sensors are listed. [ABSTRACT FROM AUTHOR]

Flexible indium‐tin‐oxide (ITO)‐based homojunction thin‐film transistors (TFTs) are fabricated on cellulose‐nanofiber‐soaked paper substrates. The paper is simultaneously used as the gate dielectric and substrate. Source/drain electrodes and a channel layer are sputtered by one‐step radio‐frequency sputtering deposition. The paper exhibits a very large specific electric‐double‐layer capacitance of 2.3 µF cm−2 due to the existence of mobile protons. The flexible ITO‐based TFTs can operate at a low voltage of 2.0 V and show a relatively high ION/IOFF ratio of 7.5 × 106. Furthermore, no obvious electrical degradation is observed at various bending radii. Finally, inverter and NAND logic operation are demonstrated by the TFTs together with two in‐plane gates. Such flexible homojunction TFTs on low‐cost and biodegradable paper are promising for portable paper electronics. [ABSTRACT FROM AUTHOR]

[Display omitted] All-wrapped transistors consisting of two-dimensional transition-metal dichalcogenide channels are appealing candidates for post-silicon electronics. Based on the Boltzmann transport theory, here we report a comprehensive theoretical survey on the performance limits for monolayer MoS 2 transistors with three prototypical gate dielectrics (Al 2 O 3 , HfO 2 and BN), by including primary extrinsic charge scattering mechanisms present in practical devices. A concept of "dead space" between the dielectrics and channels is proposed and used in calculation to ameliorate the general overestimation in scattering intensity of surface optical phonons, which enables an accurate description of electronic transport behavior. Crucial device indices, including charge mobility and current density, are thoroughly analyzed for transistors at post-silicon technological nodes beyond 1 nm. The on-state current is estimated to be generally greater than 2 mA μm−1 at channel lengths below 10 nm. The results clarify the potential benefits in performance from extremely miniaturized monolayer-channel transistors for More-Moore electronics. [ABSTRACT FROM AUTHOR]

Flexible organic/inorganic hybrid and proton/electron coupled neuron transistors are self-assembled on paper substrates at room temperature. Solution-processed chitosan-based proton conductor gate dielectrics show a high electric-double-layer specific gate capacitance, which is favorable for low voltage portable application. High performance logic operations are realized on such flexible neuron transistors depending on the operation modes, i.e., 'OR' logic for enhancement-mode device and 'AND' logic for depletion-mode device. Proton/electron interfacial coupling in chitosan-gated neuron transistors is promising for the biological and sensing applications. [ABSTRACT FROM AUTHOR]

In bio-neural systems, ionic fluxes dominate the regulation of neuroplasticity. Inspired by such biological strategies, indium-zinc-oxide (IZO) transistors gated by nanogranular SiO 2 electrolyte films were proposed for synaptic behavior emulations. Due to the strong proton/electron coupling effect, the carrier density of IZO channel layer can be effectively tuned by a pH buffer solution on the SiO 2 electrolyte dielectrics. The pH-dependent synaptic responses, such as excitatory postsynaptic current (EPSC) and paired pulse facilitation (PPF), were discussed in detail based on the surface charging effect. Most importantly, an enhanced pH sensitivity in terms of the relative gain of EPSC amplitude between pH = 4 and pH = 10 was demonstrated by multi-spike trains. Such IZO-based synaptic transistors are promising for low-power neuromorphic sensing systems. Unlabelled Image • Indium-zinc-oxide synaptic transistors gated by SiO 2 electrolyte films were proposed for synaptic behavior emulations. • The pH-dependent synaptic responses were discussed in detail based on the surface charging effect. • The pH sensitivity in terms of relative amplitude gain between pH = 4 and pH = 10 can be enhanced by multi-spike trains. [ABSTRACT FROM AUTHOR]

Human brain is a powerful biological computer that can processing a large number of cognitive tasks simultaneously. Inspired by our brain, many emerging devices have been developed for neuromorphic computing and perception in recent years. Due to the interfacial electron/ion coupling, electric-double-layer (EDL) transistors gated by electrolytes are promising candidates for neuromorphic devices. Here, we demonstrate a multi-terminal indium-tin-oxide (ITO)-based EDL transistor gated by chitosan electrolyte and this device exhibits good electrical properties. Short-term synaptic plasticity modulation and neuron functions (temporal integration, coincidence detection) are investigated. Our results indicate that oxide-based EDL transistors are promising for neuromorphic application. [Display omitted] • A multi-terminal oxide-based electric-double-layer transistor is fabricated. • Polysaccharide polymer acts as gate dielectrics. • Short-term synaptic plasticity modulation is investigated. • Temporal integration and coincidence detection are realized. [ABSTRACT FROM AUTHOR]