SNU College of Engineering (Dean Kook Heon Char) announced on 26^th the development of stretchable artificial neuron that mimics the sensorimotor neurons of organisms by the joint research under Professor Tae-woo Lee of SNU Department of Materials Science and Engineering and Professor Zhenan Bao of Stanford.
 
Biomimicry, which is the design and production of unique structures that models biological entities and processes, is a core technology of Artificial Intelligence (AI) and robotics at this Fourth Industrial Revolution. Especially, sensors and soft robots that mimic the sensorimotor system and neuromorphic engineering that mimic the brain and the nervous system allow the creation of human-interactive robots like the humanoid robot.   
 
Until present, researches on biomimetic sensor technology, robotics, and neuromorphic technology have been conducted independently from each other. Neuromorphic engineering had its focus on overcoming the limitation of digital computer by imitating the learning and memory processes of the brain. On the other hand, researches to model the sensorimotor system lingered at the early research stage.
 
Hence, the joint-research team of Lee and Bao developed a sensorimotor synapse that controls the artificial muscle using the light sensitive optoelectronic synapse. The sensorimotor synapse consists of an artificial light sensory synapse that resembles the photoreceptor, stretchable organic nanowires that transmit electrical impulse, and a polymer actuator that mimics muscle fibers. The organic artificial synapses receive action potentials from the artificial photoreceptors to stimulate the artificial muscle fibers. Then, the artificial muscle contracts as the artificial nerves “fire” action potentials.
 
In addition, the optical wireless communication via the optoelectronic synapse that outputs light signals representing the morse code suggests a new communication method between human and robot. A 100% prestrained synapse composed of organic nanowires can maintain its electric properties; thus, opening up the possibility for applications to soft robots and neural prosthesis. Such organic substances, like the nanowires in this case, share a strength that their electric and mechanical properties can be easily manipulated.
 
Professor Lee explained, “This low-electricity and self-powered stretchable artificial sensorimotor synapse can be applied to the development of biomimetic robots in the future. The merge of material, electrical, chemical, mechanical, and biological engineering has brought the success of this study. The findings set a milestone for the development of neural prosthetic devices for diseases like the Alzheimer’s disease, Parkinson’s disease, Lou Gehrig’s disease, etc.”
 
The research findings are featured online on Science Advances, sister journal of the international journal Science, as of November 23^rd.
 
Meanwhile, this research was conducted with the support of the Leading Researcher Program of the Ministry of Science, ICT & Future Planning and the National Research Foundation of Korea and the Creative-Pioneering Researchers Program of SNU.
 

Glossary
- Science Advances: sister journal of the Science, one of the most prestigious science journals
 
- Nervous System: is responsible for the control and communication of body, taking in external stimulus and processing them to stimulate other body systems; consists of the central nervous system (CNS) and the peripheral nervous system (PNS); while CNS consists of the brain and spinal cord, the PNS consists of bundles of sensory and motor nerves that link the entire body up to the CNS
 
- Neuron: basic unit of the nervous system; a.k.a. the nerve cell; types largely divide to sensory neuron, interneuron, and motorneuron; The sensory neuron delivers the stimuli received at mechanoreceptor to interneuron. The interneuron combines the signals to give appropriate instructions. The motorneuron then delivers interneuron’s orders to a locomotive organ.
 
- Synapse: A bridge between two neurons where a neuron passes signal to the other neuron. The nervous system is basically a network of neurons and synapses. The synapse, being in charge of memory-related functions, takes a crucial role in the information processing of nervous system.
 
- Organic Device: An electronic device that uses organic semiconductor. Plastic is a type of organic matter. Organic matter conventionally has been insulator of electricity, but recent researches have uncovered many organic matters with semi-conductive properties. Organic semiconductors are easy to manipulate chemically; can be printed through solution process to create cheap interface system; flexible like real organisms.
 
- Flexible: a property of bending easily
 
- Prosthesis: an artificial device that performs the functions of a missing limb from accident, disease, or from birth; examples include prosthetic hand[arm], prosthetic leg, and prosthetic eye
 
- Neuromorphic: describing any semiconductor devices that mimic the nervous system
 
- Optogenetics: a genetic engineering technology that uses light for targeted, fast control of molecular events in living cells or organisms
 
- Neuromuscular Junction: synapse that links the a motor neuron to a muscle fiber
 
- Photodetector: converts light into electrical signal; serves as the photoreceptor for an artificial nerve
 
- Organic Artificial Synapse: organic electrochemical device that mimics the biological synapse
 
- Neural Prostheses: an artificial device that performs the functions of damaged nerves from accident or disease; bridges the brain or other parts of the nervous system to another body part