Figure 6

Flexible and stretchable physical sensing platforms for artificial electronic skins. (a) Stretchable e-skin configured from CNT-PDMS composite film patterned with interlocked microdome arrays. (i) Schematic illustration of the structure of human skin depicting the interlocked epidermal–dermal layers and the various skin mechanoreceptors. (ii) Schematic illustration of the design of the interlocked microdome arrays and the corresponding tilted and cross-sectional SEM images of the arrays of microdomes on a composite film. Scale bars, 5 μm. (iii) Schematic illustration showing the attachment of the stress-direction-sensitive e-skin on a human arm for the directional tactile sensing and differentiation of a range of mechanical stimuli, such as normal, shear, lateral stretch, and bending forces. (iv) Schematic illustration showing the configuration of 3×3 pixel e-skin arrays sandwiched between the cross-arrays of electrodes and PDMS layers for the three-axial directional sensing of mechanical stimuli. (v) Spatial distribution and directional mappings of external finger pushes applied on the e-skin. Adapted with permission from Ref. 7. Copyright 2015 American Chemical Society. (b) Strain-engineered artificial e-skin sensor arrays integrated with a fingerprint-like structure. (i) Schematic illustration showing an exploded view of the device configuration with the corresponding enlarged view of the fingerprint-like structure with its four strain and one temperature sensors. (ii) Optical image showing the actual fabricated e-skin device in a 3×3 array (top) and the corresponding enlarged image of the actual fabricated fingerprint-like structure (bottom). (iii) Optical image and schematic illustrations depicting the two-dimensional force and temperature mapping capability of the 3×3 array e-skin device in response to external stimuli, such as finger touch. Scale bars, 2 cm. Adapted with permission from Ref. 46. Copyright 2015 American Chemical Society. (c) Smart prosthetic e-skin sensor constructed from stretchable silicone nanoribbon (SiNR) electronics. (i) Optical image illustrating the smart artificial e-skin with its stretchable SiNR electronics laminated compliantly onto a prosthetic hand. Inset shows a 20% stretched e-skin. Scale bars, 1 cm. (ii) Schematic illustration depicting the exploded view of the device architecture of the smart e-skin. (iii) Optical images of the e-skin-laminated prosthetic hand tapping a keyboard and grasping a baseball and the corresponding temporal resistance changes of the artificial e-skin in response to different external stimuli as captured and monitored by the pressure sensor. Adapted with permission from Ref. 8. Copyright 2014 Macmillan Publishers Limited.