Perceiving\nthe Spectrum of Pain: Wavelength-Sensitive\nVisual Nociceptive Behaviors in Monolayer MoS<sub>2</sub>‑Based\nOptical Synaptic Devices

Artificial visual nociceptors, which respond to noxious\nlight by\nsending pain signals to the central nervous system, are a crucial\nsensory element in bionic visual systems. However, existing efforts\nfocus on mimicking nociceptive responses to specific wavelengths of\nlight, especially ultraviolet, with little consideration given to\nwavelength-sensitive nociceptive behaviors. Here, we have developed\nan optical synaptic device based on monolayer MoS<sub>2</sub>, featuring\nwavelength-sensitive visual nociceptive behaviors similar to human\neyes. Except for typical synaptic functions and logical operations,\nessential behaviors of visual nociceptors are successfully emulated.\nMore importantly, the device also realizes the emulation of the wavelength-sensitive\nnociceptor, that is, the shorter the wavelength of light the stronger\nthe perception, and the secondary damage from long-wavelength light.\nCharge trapping and detrapping from interfacial defect-states, in\nconjunction with the band nesting effect, enable these wavelength-sensitive\nvisual nociceptive behaviors of the devices. This work represents\nan important step toward endowing bionic vision systems with advanced\nvisual capabilities.