Ajou News

NEW Prof. Seo Hyung-tak’s team develops an artificial synapse for tactile perception

  • 2020-05-15
  • 3686

 

A team of researchers led by Professor Seo Hyeong-tak of Ajou University has developed an artificial synapse for tactile perception. The new device, which emulates tactile perceptions involving touch and nerves, features a hetero-junction of oxides. Expected applications include skin-attached electronics and artificial intelligence (AI) sensors.
 
Prof. Seo (Dept. of Materials Science and Engineering / Graduate Dept. of Energy Systems, pictured) and his team’s work was published under the title, “An artificial piezotronics synapse for tactile perception,” in an online issue of Nano Energy on April 15, 2020. Also on the team from Ajou University were Prof. Kim Sang-wan (Dept. of Electrical and Computer Engineering) and Dr. Mohit Kumar (researcher, Dept. of Materials Science and Engineering). 
 
Of the five senses humans have at their disposal, tactile perception involves the signals stimulated by a touch traveling from the stimulus receptor at the terminal of the skin to cranial nerves via the neural network. Humans are able to discern an incredibly wide range of touches on their skin. Combined with emotions of varying depths, these tactile perceptions can become part of human memory.
 
An artificial synapse that emulates the human tactile perception therefore epitomizes a highly sophisticated technology capable of detecting the wide variety of touches exerted from the outside world with finesse and precision, saving perceptions thereof, and retrieving them in a memory-like fashion.
 
Prof. Seo’s team achieved such an advanced artificial synapse, featuring a hetero-junction of nickel and zinc oxides (NiO and ZnO) that emulates tactile stimulation of nerves. Specifically, the synapse was designed to emulate how hair detects changes in external pressure using a vertically structured sensor featuring the hetero-junction of oxides. It is this sensor that produces changes in the current-voltage curve in response to changing intensity and directions of pressure in a fashion similar to how the human body perceives touch.
 
 
Concept of a very transparent and flexible artificial synapse that emulates environment-adaptable tactile perceptions
 
The team’s discovery is all the more significant due to its ability to remember tactile changes in electric currents, in the form of conserved charges, for a certain period of time, in a fashion similar to non-volatile memory. The artificial synapse is capable of emulating all the typical functions of actual neuron synapses, such as perceiving changes in signals, whether in intensity or over time and in size. The invention therefore bears much functional similarity to an actual in-vivo tactile neural circuit.
 
Prof. Seo explained: “We created a test touch pad with multiple artificial synapses arranged on it, and discovered that the pad is capable of effectively detecting temporal-spatial information from external variables, such as the amplitude and duration of stimuli. We also demonstrated that the synapse is capable of discerning different pressure patterns.”
 
The artificial neural circuit architecture that simulates sensory nerve functions from touch to the brain requires the integration of a pressure sensor, a connecting cable, and an artificial synapse. This is an extremely sophisticated technology that involves quite complex machinery and ultra-low energy consumption. Prof. Seo’s team has created an ultra-energy-light and high-precision artificial synapse, using a relatively simple manufacturing process, that can adjust output in response to variations in tactile input.
 
Prof. Seo further commented: “The artificial synapse we developed this time is comparatively less complex and consumes less energy than other preexisting and similar tactile circuits. At the same time, it provides superior environment-adaptable detections of touch. We anticipate that our invention can be made into various applications, including AI sensors, skin-attachable electronics, robotics, and prosthetic limbs for people with disabilities.”
 
The study was conducted with support from the New Future Device and Original Technology Development Program  and the Basic Research Support Program for Established and New Projects , sponsored by the Ministry of Science and ICT and the National Research Foundation of Korea, respectively.