Bioinspired Hairy Skin Electronics for Detecting the Direction and Incident Angle of Airflow

Abstract

The human skin has inspired multimodal detection using smart devices or systems in fields including biomedical engineering, robotics, and artificial intelligence. Hairs of a high aspect ratio (AR) connected to follicles, in particular, detect subtle structural displacements by airflow or ultralight touch above the skin. Here, hairy skin electronics assembled with an array of graphene sensors (16 pixels) and artificial microhairs for multimodal detection of tactile stimuli and details of airflows (e.g., intensity, direction, and incident angle) are presented. Composed of percolation networks of graphene nanoplatelet sheets, the sensor array can simultaneously detect pressure, temperature, and vibration, all of which correspond to the sensing range of human tactile perceptions with ultrahigh response time (<0.5 ms, 2 kHz) for restoration. The device covered with microhairs (50 μm diameter and 300 μm height, AR = 6, hexagonal layout, and ∼4400/cm2) exhibits mapping of electrical signals induced by noncontact airflow and identifying the direction, incident angle, and intensity of wind to the sensor. For potential applications, we implement the hairy electronics to a sailing robot and demonstrate changes in locomotion and speed by detecting the direction and intensity of airflow.

Crack-based and Hair-like Sensors Inspired from Arthropods: A Review

“…The realization of energy conversion depends on the sensory cells, which play the role of the transducer. In the last century, people have conducted detailed research on the energy conversion process of spider trichobothria [113][114][115] . As shown in Fig.…”

“…Chun et al developed a multi-hair sensor that can be used for multi-mode detection like skin [115] . Through changing the stencil mask to a flexible substrate, the array of sensors and electrodes are fabricated by a simple thermal spray process of graphene nanoplates (GNPs).…”

“…11 Schematic diagram of the micro-scale HLS for flow detection. (a) Micro-scale HLS based on the principle of resistance change [115] . (i) Sensor array of graphene fabricated by filling micro-hairs; (ii) the simulation results when the hair rod is bent are displayed; (iii) photograph of flexible graphene nanoplatelets electronic skin.…”

Artificially innervated self-healing foams as synthetic piezo-impedance sensor skins

“…Such synthetic skins have great potential in a large variety of applications including health care, human-machine interactions, and robotics 3 . Although many different tactile sensing e-skins have been demonstrated [8][9][10][11] , an integrated e-skin sensor material that is self-healing, detects proximal precontact events and senses force directions simultaneously have yet to be demonstrated. There are excellent efforts to use ionic gels as artificial nerves in e-skins with organic transistors 12 , but the ionic gels based nerves did not show tactile sensitivity.…”

“…Moreover, the use of such 2D electrode patterns typically detects normal forces only. While there are reports on e-skins that detect both normal and shear forces 8,9,11,[13][14][15][16] , most of them require encapsulation with sandwiched structures to work (Table 1). There are also designs of piezoresistive material pillars to achieve the normal and shear-force sensing, but these are not self-healing 17 .…”