Embedded 3D Printing of Strain Sensors within Highly Stretchable Elastomers

Abstract

A new method, embedded-3D printing (e-3DP), is reported for fabricating strain sensors within highly conformal and extensible elastomeric matrices. e-3DP allows soft sensors to be created in nearly arbitrary planar and 3D motifs in a highly programmable and seamless manner. Several embodiments are demonstrated and sensor performance is characterized.

Design, fabrication and control of soft robots

“…With layered channel geometries, it is possible to tailor sensors for measuring various strains including tensile, shear 50 , or curvature 51 . To address the fabrication challenges involved with injecting complex channel networks with liquid conductor, recent work has investigated mask deposition of the conductor 52 , or direct 3D printing of conductive material 53 . Alternatively, exteroceptive sensing may be used to measure the curvatures of a soft robot's body segments in real time 30 .…”

Untethered soft robotics

“…Furthermore, owing to the inherent conductivity of these materials, the fabrication of simple sensors is both scalable and robust using a variety of techniques, including screen printing 87,94 , direct writing 94,95 and spray deposition 96 . Sencadas et al developed a conductive ink that can be sprayed directly on soft materials to function as a piezoresistive strain sensor, without the need for encapsulation 96 .…”

3D Printing of Transparent and Conductive Heterogeneous Hydrogel–Elastomer Systems

“…[5][6][7][8] Although many stretchable conductors exist, including liquid metals, [9,10] nanowires, [11,12] nanoribbons [13] , pre-stretched elastomer fibers with conductive coatings, [14] and micro-cracked metals, [15,16] these materials have generally been unable to achieve high levels of optical transparency while maintaining high conductivities and stretchability; a feature that would enable their use in optogenetics [17] or allow optical imaging of the underlying substrate. Conventional strategies of incorporating metallic components with elastomers to attain stretchability also yield non-trivial failure modes such as liquid metal leakage [8] and hard-soft material interfacial failure [18] .…”

“…For applications where a higher resolution is required, many techniques and products are available to adjust the rheological behavior of the PDMS precursor. [5,24,[43][44][45][46][47] The development of the hydrogel precursor for our extrusion printing was more demanding and required a balance between conductivity, stability, and rheological characteristics.…”