Spike-timing based coding in neuromimetic tactile system enables dynamic object classification

Coding dynamic tactile information in spike timing is essential to human haptic exploration and dexterous object manipulation. Conventional electronic skins generate frames of tactile signals upon interaction with objects and are unfortunately ill-suited for efficient coding of temporal information and rapid feature extraction. Here, we report a neuromorphic tactile system that uses spike timing, especially the first-spike timing, to code dynamic tactile information about touch and grasp. This strategy enables the system to seamlessly code highly dynamic information with millisecond temporal resolution on par with the biological nervous system, yielding dynamic extraction of tactile features. Upon interaction with objects, the system rapidly classifies them in the initial phase of touch and grasp, thus paving the way to fast tactile feedback desired for neuro-robotics and neuro-prosthetics., The method is provided in SM. In brief, the raw data of spike trains in voltage were generated and collected by using the e-skin that touched surfaces and grasped objects. The raw data was converted to digital spike trains with 1 as a spike and 0 as non-spike. The processed spike trains were analyzed to study the encoding performance of the system and were used to train and test the spiking neural networks for classification tasks. The tabular data provided are corresponding to the main text figures (i.e., Fig 2, Fig 3 and Fig 4). , , # Spike-Timing Based Coding in Neuromimetic Tactile System Enables Dynamic Object Classification

## Explanation of Figures

* Fig 2C: Typical spike trains in the ensembles of afferents (with indices 29 through 32 and 36 through 39) on the fingertip in response to touching the hard hemisphere (left) and soft hemisphere (right). The spike trains have been digitalized. The center of spike trains is intentionally aligned to t=2s just for illustration.
* Fig 2D: Activity over population, which is the time-dependent spike rate by counting spikes in all afferents within a bin size of 0.01 s, in response to touching the hard hemisphere (left) and soft hemisphere (right).
* Fig 2F: 1st-spike patterns (radar maps) illustrating the 1st-spike sequences and latencies of the ensemble of afferents, in response to touching the hard hemisphere (left) and soft hemisphere (right). The distance from the pole defines the relative 1st-spike latency to t0, while the angle denotes the artificial afferen...