The role of fingerprints in the coding of tactile information probed with a biomimetic sensor

TL;DR

This study demonstrates that fingerprints influence tactile vibrations in a way that enhances the sensory signals for fine texture perception, using a biomimetic sensor to mimic human fingertip mechanics.

Contribution

It introduces a biomimetic sensor with fingerprint-like ridges to investigate how fingerprints affect tactile vibration spectra during surface scanning.

Findings

Fingerprints induce a dominant vibration frequency matching human tactile sensitivity.

The sensor's vibration spectrum is dominated by a frequency set by ridge spacing and scanning speed.

Fingerprints may serve to spectral select and amplify tactile signals for fine texture perception.

Abstract

In humans, the tactile perception of fine textures (spatial scale <200 micrometers) is mediated by skin vibrations generated as the finger scans the surface. To establish the relationship between texture characteristics and subcutaneous vibrations, a biomimetic tactile sensor has been designed whose dimensions match those of the fingertip. When the sensor surface is patterned with parallel ridges mimicking the fingerprints, the spectrum of vibrations elicited by randomly textured substrates is dominated by one frequency set by the ratio of the scanning speed to the interridge distance. For human touch, this frequency falls within the optimal range of sensitivity of Pacinian afferents, which mediate the coding of fine textures. Thus, fingerprints may perform spectral selection and amplification of tactile information that facilitate its processing by specific mechanoreceptors.