Type II mechanoreceptors and cuneate spiking neuronal network enable touch localization on a large-area e-skin

The sense of touch is essential for humans to perceive, locate and react to physical stimuli. Notwithstanding the substantial advancements in e-skin research and related applications with collaborative robots and bionic prostheses, biomimetic intelligence remains a challenge in the attempt to understand and mimic somatosensory processing schemes. In this work, we present a large-area e-skin embedded with photonic fibre Bragg gratings, capable of decoding touch localization through a bioinspired two-layered spiking neuronal network. The implemented biomimicry of slowly adapting and fast-adapting type II primary afferents, cuneate neurons with overlapping receptive fields and neuroplasticity, enable unsupervised learning in localizing tactile stimuli with an error lower than 10 mm, and two-point discrimination thresholds matching human psychophysical thresholds in the forearm. These results align with biological findings and offer a promising step towards the development of bionic systems, opening new avenues for both practical applications and scientific explorations of somatosensation.