Polarity‐Differentiated Dielectric Materials in Monolayer Graphene Charge‐Regulated Field‐Effect Transistors for an Artificial Reflex Arc and Pain‐Modulation System of the Spinal Cord

Abstract

The nervous system is a vital part of organisms to survive and it endows them with remarkable abilities, such as perception, recognition, regulation, learning, and decision‐making, by intertwining myriad neurons. To realize such outstanding efficacies and functions, many artificial devices and systems have been investigated to emulate the operating principles of the nervous system. Here, an artificial reflex arc (ARA) and artificial pain modulation system (APMS) are proposed to imitate the unconscious behaviors of the spinal cord. GdxOy‐ and AlxOy‐based charge‐regulated field‐effect transistors (CRFETs) with a monolayer graphene channel are fabricated and adopted as inhibitory and excitatory synapses, respectively, under the same pulse signals to mimic the biological reflex arc through a connection with a poly(vinylidene fluoride‐co‐trifluoroethylene)‐based actuator. Additionally, a memristor is integrated with a CRFET as the interneuron to regulate the Dirac point by controlling the voltage drop on the graphene channel, analogous to the descending pain‐inhibition system in the spinal cord, to prevent excessive pain perception. The proposed ARA and APMS provide a significant step forward to realizing the functions of the nervous system, giving promising potential for developing future intelligent alarm systems, neuroprosthetics, and neurorobotics.

Artificial Neuron Devices

“…respectively, providing a unified operating principle. 521 The CRFETs use Gd x O y and Al x O y as dielectric layers to produce a voltage shift in different directions under the same input signals, due to opposite polarities of oxide charges within the dielectric layers (Figure 27e,f). This artificial efferent nerve device was connected to a soft electrochemical actuator to control the bending movement as a demonstration of artificial reflex response (Figure 27g).…”

“…Interneurons use neurotransmitters to transmit information between sensory and motor neurons, as well as other interneurons, allowing them to communicate with each other. Despite significant progress in developing artificial systems that mimic biological synapses, few are capable of directly interacting with neurotransmitters. − To address this, Keene et al designed a biohybrid artificial synapse that responds to the neurotransmitter dopamine, employing conductive polymer PEDOT:PSS as both the gate and channel material for the synaptic transistor . When dopamine is present, it undergoes oxidation at the postsynaptic gate, resulting in a change in the electrode’s charge state and the induction of ion flow in the electrolyte, altering the conductance of the postsynaptic channel (Figure a).…”

“…Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC). (e–g) Reproduced with permission from ref . Copyright 2022 Wiley.…”

“…Inhibitory synapses on motor neurons are crucial for controlling and fine-tuning muscle activity, allowing for precise and coordinated movements. Fu et al developed Gd x O y - and Al x O y -based charge-regulated field-effect transistors (CRFETs) that act as artificial inhibitory and excitatory synapses, respectively, providing a unified operating principle . The CRFETs use Gd x O y and Al x O y as dielectric layers to produce a voltage shift in different directions under the same input signals, due to opposite polarities of oxide charges within the dielectric layers (Figure e,f).…”

Position Measurements Using Magnetic Sensors for a Shape Memory Alloy Linear Actuator

“…This kind of system has been implemented to emulate the behaviour of biological systems [ 30 , 31 , 32 ]. It must be pointed out that this kind of mechanism is highly valuable when some kinds of transmission mechanisms are applied, such as a driven cable [ 33 , 34 ], or when a special class of smart actuator is implemented such as the shape memory alloys [ 27 , 35 , 36 ], pneumatic actuators [ 37 , 38 ], and electro-chemical actuators [ 39 , 40 ].…”