A MEMS-based tactile sensor to study human digital touch: mechanical transduction of the tactile information and role of ﬁngerprints
Laboratoire de Physique Statistique, CNRS/ENS/University Paris
6/University Paris 7, Paris, France
2 Physics of Geological Processes, University of Oslo, Oslo, Norway
a e-mail: firstname.lastname@example.org
We present recent results showing that human epidermal ridges (ﬁngerprints) could play a central role in ﬁne texture discrimination tasks by spatially modulating the contact stress ﬁeld between the ﬁngertip and the substrate. Using an original biomimetic ﬁnger whose surface is patterned with parallel ridges, we demonstrate that the subsurface stress signals elicited by continuous rubbing of randomly textured substrates is dominated by ﬂuctuations at a frequency deﬁned by the inter-ridge distance divided by the rubbing velocity. In natural exploratory conditions, this frequency matches the best frequency of one type of mechanoreceptors, namely the Pacinian corpuscles, which are speciﬁcally involved in the tactile coding of ﬁne textures. The use of white-noise patterned stimuli has alloowed us to extract, using a reverse-correlation analysis, the stimulus-signal response function associated with roughness modality. Its shape could provides spectral, spatial and directional selectivity to the digital tactile system. It oﬀers a physiological basis for the recently proposed hypothesis of a dual-coding (spatio-temporal and vibratory) of tactile information.
© Owned by the authors, published by EDP Sciences, 2010