Conductive and Elastic 3D Helical Fibers for use in Washable and Wearable Electronics

Conductive fibers for biomedical applications

“…Reproduced with permission from Ref. [ 83 ]. Copyright 2020, WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.…”

“…Even though effective bonding between the conductive components and the fiber surface can be realized by as-stated modification methods, the huge difference in mechanical properties (especially tensile elongation) will inevitably deactivate the conductive element under physiological deformation. Therefore, serpentine structures, mesh structures, pre-strained wavy structures, and buckling structures have been involved in structure designs of conductive fibers [ 96 ], with the same principle of reserving extra length/volume for the intrinsically rigid conductive components when the elastic matrix is undeformed [ 38 , 83 , 97 ]. Deposition of conductive components on pre-stretched substrates or constructing helix-structured conductive fibers turn out to be the easiest and most useful approach to develop elastic conductive fibers.…”

Weaving a magnificent world: 1D fibrous electrodes and devices for stretchable and wearable electronics

“…29 This section discusses the conductive nanomaterials most commonly used to fabricate 1D fibrous flexible electronic devices. 30…”

“…When it is applied to electronic devices such as conductive fibers, the conductive network will be changed by stretching, and the electrical properties will fluctuate seriously along with the strain, which cannot meet the requirements of stable conductive properties. 30 Therefore, the structure can be designed by twisting, helix, folding, winding, and other methods, to avoid the reduction of yarn conductivity during the mechanical stretching process. The structural design not only has the inherent tensile properties of the original base material but also has advantage of the geometric deformation of its structure for higher tensile properties, thus effectively maintaining contact between the conductive materials in the yarn, thereby reducing the change in the yarn conductivity during the stretching process.…”

Highly-integrated, miniaturized, stretchable electronic systems based on stacked multilayer network materials

“…A higher function density can yield a more miniaturized device system (with a smaller lateral size) than that with a lower function density. While various strategies of stretchable interconnects [e.g., bridge-shaped designs, serpentine interconnects, fractal designs, and helical interconnects (49)(50)(51)(52)(53)(54)(55)] have been developed, the function densities of device systems based on these technologies (mostly in the form of an island-bridge construction) are typically below 80% because of the fundamental limit (100%) of function density for the single-layer layout. These technologies based on the single-layer layout can hardly achieve, simultaneously, a large function density (e.g., >60%) and a sufficient high stretchability (e.g., >20%) for miniaturized multifunctional systems (e.g., consisting of >15 ICs to realize two or more functions) (51,(56)(57)(58)(59)(60)(61).…”