Artificial Muscles from Hybrid Carbon Nanotube‐Polypyrrole‐Coated Twisted and Coiled Yarns

Abstract

in the significant progress in soft-robotics, flexible prosthetics, and exoskeletons that either boost human performance or assist disabled people in carrying out day-today tasks. One of the significant innovations is introducing soft and lightweight actuating materials (artificial muscles) that can mimic biological muscles and operate smoothly and silently. [1] The current materials of interest for artificial muscles are carbon nanotubes (CNT), [2] graphene, [3] shape memory alloys (SMA), [4] shape memory polymers (SMP), [5] conductive polymers, [6] and highly oriented polymer yarns [7] that can be induced thermally, chemically, photonically, or electrochemically to obtain muscle-like actuation. Artificial muscles made from polymeric or nano-carbon-based yarns can find versatile applications ranging from assistive wearable artificial muscles for biomedical rehabilitation or assistance for daily activities, bioinspired and biomimetic systems, for handling delicate objects, and on-demand movement. [8] CNT yarn actuators are of great interest in the field of electrochemically or electrothermally induced wearable artificial muscle technologies. [2a,9] These actuators exhibit excellent mechanical properties needed for wearable textile exoskeletons. [2c,10] Recently, the feasibility of using multi-walled CNT forest drawn twisted or coiled yarns was demonstrated in terms of both tensile and rotational actuation. As high as 3% tensile actuation and 12.6° mm-1 rotational actuation was reported from an electrothermally activated twist-spun wax-filled CNT yarn when subjected to 25-210 °C temperature variations. [9c] On the other hand, electrochemically induced twist-spun CNT yarns have shown a maximum of 180° mm-1 torsional rotation and 0.7% axial strain in an organic electrolyte (0.2 m tetrabutylammonium hexafluorophosphate (TBA.PF6) in acetonitrile) when pulsed from-2.0 to +2.0 V versus Ag/Ag + reference. [9b] However, due to the reasonably high cost associated with their fabrication, these CNT yarn actuators have limited practicability in smart textiles where low cost is desirable. Therefore, the interest in using inexpensive textile yarns has grown. Several researchers have shown the feasibility of using such yarns to construct simple textile actuators actuated by thermal, [7b] electrothermal, [9a] electronic, [11] electrochemical, [9b,12] or electrical [9c] energy inputs. Similar to CNT yarn muscles, twisted and coiled textile yarns Electrochemically or electrothermally driven twisted/coiled carbon nanotube (CNT) yarn actuators are interesting artificial muscles for wearables as they can sustain high stress. However, due to high fabrication costs, these yarns have limited their application in smart textiles. An alternative approach is to use off-the-shelf yarns and coat them with conductive polymers that deliver high actuation properties. Here, novel hybrid textile yarns are demonstrated that combine CNT and an electroactive polypyrrole coating to provide both high strength and good actuation properties. CNT-coated po...

Textile Technology for Soft Robotic and Autonomous Garments

“…Coils, achieved through overtwist or winding around a mandrel, can improve tensile stroke tenfold in some systems because the torque generated through untwisting the yarn pulls adjacent coils together. [ 348,351–353 ] Plying an overtwisted and coiled CNT yarn in an opposing direction creates a torque‐balanced structure and allows for a self‐contained structure that can contract without external tethering. [ 349 ]…”

“…Active yarns formed from organic conductors such as poly(3,4‐ethylenedioxythiophene) (PEDOT) and polypyrrole (PPy) (PEDOT:PPy) applied to cellulosic fabrics and PET‐CNT‐PPy composites have been developed to actuate based on this ion‐motion mechanism. [ 353,357 ]…”

Constructing a Segregated Magnetic Graphene Network in Rubber Composites for Integrating Electromagnetic Interference Shielding Stability and Multi-Sensing Performance

“…Nowadays, flexible, wearable electronic devices with superior sensing properties that can monitor the human body’s physical health, walking movement, state changes, etc., play a significant role in the field of smart products in our daily lives [ 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ]. Additionally, it is important to prepare flexible composites with both excellent EMI shielding and sensing properties.…”

Fast and High‐Strain Electrochemically Driven Yarn Actuators in Twisted and Coiled Configurations

“…The hole was sealed with epoxy glue to prevent any leakage of the Figure 8. Comparison of A) maximum actuation strain and B) actuation speed of electrochemically activated CP yarn and fiber actuators: a) this work-coiled PEDOT:PSS coated polyamide 6, b) this work-twisted PEDOT:PSS coated polyamide 6, c) polypyrrole/PEDOT coated Lyocell, [2a] d) polypyrrole/PEDOT:PSS coated Viscose, [9] e) polypyrrole/PEDOT coated Elastane, [2a] f) carbon particle mixed polyamide, [1c] g) carbon particle mixed silicon, [1c] h) silver coated polyamide, [1c] i) carbon particle mixed cellulose, [1c] j) polyester yarn wounded with stainless steel wire, k) polyester yarn wounded with Sn coated copper wire, [1c] l) gold coated polyester yarn, [1c] m) PANI:AMPSA fiber, [28] n) wet-spun chitosan/polypyrrole microfiber, [29] o) hollow PPy tubular fiber, [30] p) Pt wire wrapped PPy hollow fiber, [30] q) CNT/PPy coated twisted PET yarn [31] and r) CNT/PPy coated coiled PET yarn. [31] Figure 9.…”