The distributed network of receptors, neurons, and synapses in the somatosensory system efficiently processes complex tactile information. We used flexible organic electronics to mimic the functions of a sensory nerve. Our artificial afferent nerve collects pressure information (1 to 80 kilopascals) from clusters of pressure sensors, converts the pressure information into action potentials (0 to 100 hertz) by using ring oscillators, and integrates the action potentials from multiple ring oscillators with a synaptic transistor. Biomimetic hierarchical structures can detect movement of an object, combine simultaneous pressure inputs, and distinguish braille characters. Furthermore, we connected our artificial afferent nerve to motor nerves to construct a hybrid bioelectronic reflex arc to actuate muscles. Our system has potential applications in neurorobotics and neuroprosthetics.
Organometal halide perovskite synaptic devices are fabricated; they emulate important working principles of a biological synapse, including excitatory postsynaptic current, paired-pulse facilitation, short-term plasticity, long-term plasticity, and spike-timing dependent plasticity. These properties originate from possible ion migration in the ion-rich perovskite matrix. This work has extensive applicability and practical significance in neuromorphic electronics.
Synapses are essential to the transmission of nervous signals. Synaptic plasticity allows changes in synaptic strength that make a brain capable of learning from experience. During development of neuromorphic electronics, great efforts have been made to design and fabricate electronic devices that emulate synapses. Three‐terminal artificial synapses have the merits of concurrently transmitting signals and learning. Inorganic and organic electronic synapses have mimicked plasticity and learning. Optoelectronic synapses and photonic synapses have the prospective benefits of low electrical energy loss, high bandwidth, and mechanical robustness. These artificial synapses provide new opportunities for the development of neuromorphic systems that can use parallel processing to manipulate datasets in real time. Synaptic devices have also been used to build artificial sensory systems. Here, recent progress in the development and application of three‐terminal artificial synapses and artificial sensory systems is reviewed.
We
fabricated a nanowire-channel intrinsically stretchable neuromorphic
transistor (NISNT) that perceives both tactile and visual information
and emulates neuromorphic processing capabilities. The device demonstrated
excellent stretching endurance of 1000 stretch cycles while retaining
stable electrical properties. The device was then applied as a multisensitive
afferent nerve that processes information in parallel. Compatible
with skin deformation, the devices are attached to fingers to serve
as conformal strain sensors and neuromorphic information-processing
units for gesture recognition. The excitatory postsynaptic current
in each device represents shape changes and is then analyzed using
softmax activation processing of the neural network to recognize gestures.
A multistage neural network that uses NISNT was used to further confirm
the gestures. This work demonstrated an idea toward multisensory artificial
nerves and neuromorphic systems.
A graphdiyne-based artificial synapse (GAS), exhibiting intrinsic short-term plasticity, has been proposed to mimic biological signal transmission behavior. The impulse response of the GAS has been reduced to several millivolts with competitive femtowatt-level consumption, exceeding the biological level by orders of magnitude. Most importantly, the GAS is capable of parallelly processing signals transmitted from multiple pre-neurons and therefore realizing dynamic logic and spatiotemporal rules. It is also found that the GAS is thermally stable (at 353 K) and environmentally stable (in a relative humidity up to 35%). Our artificial efferent nerve, connecting the GAS with artificial muscles, has been demonstrated to complete the information integration of pre-neurons and the information output of motor neurons, which is advantageous for coalescing multiple sensory feedbacks and reacting to events. Our synaptic element has potential applications in bioinspired peripheral nervous systems of soft electronics, neurorobotics, and biohybrid systems of brain–computer interfaces.
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