KIST scientists develop memristor-based sensory receptor for humanoid robots

Korean scientists have developed a new class of artificial receptors based on a surface-dominated diffusive memristor, which mimic the adaptive and maladaptive operation of human sensory receptors for application to biomimetic sensory systems and humanoid robots.

Korea Institute of Science and Technology (KIST) said on Sunday its research team led by Dr. Kang Chong-yun and Dr. Yoon Jung-ho has demonstrated the electronic receptor to exhibit a selective response to innocuous stimuli with the adaptive operation. Under noxious stimuli, the output current is not generated for the adaptive receptor, whereas the nociceptor is triggered with the maladaptive operation, which means it feels pain like humans do.

This is the world's first development of a selective response device whose adaptation/maladaptation depends on the size of the stimulus. The research findings were published as a cover story in the latest edition of Advanced Science.

The research team believed that existing research to imitate human signals with electronic devices is focused on mimicking some biological properties such as neurons and synapses and started research to find out how the human body interprets and accepts changes in the external environment and how to implement this as an electronic device.

The research team developed a special device by utilizing the properties of Ag particles that easily move in response to electrical stimulation. The Ag is suitable for implementing a volatile threshold switching device because of its low activation energy for diffusion.

When two devices containing a small and large amount of Ag particles are connected in parallel, the device with a large amount of Ag particles does not respond to a weak stimulus. A weak filament is formed in the device with a small amount of Ag particles, but the filament breaks soon due to heat and the signal stops. This is a process of adaptation to weak stimuli.

Under a strong stimulus, the device containing a small amount of Ag particles is heated and disappears in a short time that humans cannot perceive. Filaments in the device containing a large amount of Ag particles are not easily broken and continue to generate signals. In this case, the device does not adapt to the stimulus to feel the pain.

KIST said this new artificial receptor potentially serves as the interface between external information and the internal nervous system, incorporable into all kinds of biomimetic sensory systems such as vision, tactile, auditory, gustatory, and olfactory, as well as the sensory system of humanoid robots.

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