Kinetically Tunable, Active Auxetic, and Variable Recruitment Active Textiles from Hierarchical Assemblies

Abstract

Multifunctional textiles with programmable, multi‐axial, distributed, and scalable actuation are highly desirable and presently unrealized. 1D torque‐unbalanced active yarns within 2D textile structures are exploited to produce soft and scalable active textiles that exhibit tunable displacements, forces, stiffnesses, and kinematic deformations. Through a textile hierarchy spanning active material composition, yarn construction, textile geometry, and system architecture, these active textiles accomplish kinetic tunability, variable recruitment behaviors, and auxetic effects without mechanical contact, called active auxetic effects. New modes of pre‐programmed multi‐axial performance are enabled by geometrically manipulating—specifically pre‐stressing and constraining—active filaments in torsion and leveraging their structural elastic instability within a textile geometry. The new kinematic motion afforded by torque‐unbalanced active yarns enhances the performance of active textiles, which accomplish tensile strokes over 40%, generated blocked forces up to 308 N m−1, and specific work over 0.4. kJ kg−1. Advances in active textiles are demonstrated through multifunctional 3D applications, including a variable constriction pump that exhibits sequential actuation, a wearable that conforms multi‐axially around the body, and a soft exoskeleton that performs assistive motions and on‐body anchoring simultaneously. By harnessing the capabilities of active materials within a textile hierarchy, advances in the potentiality of multifunctional textiles are presented.

Dynamic, Tunable, and Conformal Wearable Compression Using Active Textiles

“…[ 82 ] When torsion is applied to SMA filaments prior to knitting, the increase in blocked force observed is attributed to a thermally‐induced recovery of torsional deformations, which (due to the loop interconnections) produce loop rotation about the y‐axis. [ 59 ] Loop rotation is followed by stick‐slip jamming, which produces a torque that increases the total blocking forces of the active textile. To enhance the range of unit tension available for device design, active textiles were manufactured in 2‐filament and 3‐filament variations for lower pressure (consumer) and higher pressure (astronautic) applications respectively.…”

Knot‐Architectured Fabric Actuators Based on Shape Memory Fibers

“…To realize smart fabrics, wearable textile actuators are receiving extensive interest due to their excellent features including flexibility, stretchability, light weight, silent actuation, and programmability, eventually enabling safe, comfortable, and controllable interaction with the human body and vulnerable objects. [ 31 ] In the past years, textile actuators have been developed based on various materials and designs, [ 32 ] such as a multifunctional actuator with torque‐unbalanced active yarns, [ 33 ] an SMA‐based fabric muscle for wearable robots, [ 31,34 ] an active patch for wearable interactions, [ 35 ] a soft orthotic to assist human muscles, [ 36 ] and a compressive actuator with adjustable wearing tightness. [ 37 ] In these textile actuators, textiles play assistive roles such as routing force and anchoring or active roles by incorporating functional fibers in their fabric architectures.…”

Functional Nanomaterials from Waste and Low‐Value Natural Products: A Technological Approach Level

“…Advanced functional nanocomposites, nanomaterials, and complex hierarchical material systems [1][2][3][4][5] are currently considered as the means to advance and in some instances even revolutionize energy conversion, [6][7][8][9] sensors, [10][11][12][13] biosensors, [14] catalysis [15][16][17][18] and photocatalysis, [19] biotechnology, [20][21][22][23] water purification, [24,25] space exploration, [26][27][28][29] and nanomedicine. [30][31][32][33] Various methods and techniques are currently under exploration to design cheap, environmentally friendly technologies for the mass production of functional nanocomposites and nanomaterials, with the total yield for, e.g., silica reaching 1.5 million tons (Table 1) and rapidly growing.…”