Abstract

Actuator materials capable of producing a rotational or tensile motion are rare and, yet, rotary systems are extensively utilized in mechanical systems like electric motors, pumps, turbines and compressors. Rotating elements of such machines can be rather complex and, therefore, difficult to miniaturize. Rotating action at the microscale, or even nanoscale, would benefit from the direct generation of torsion from an actuator material. Herein we discuss the advantages of using carbon nanotube (CNT) yarns and/or graphene (G) fibers as novel artificial muscles that have the ability to be driven by the electrochemical charging of helically wound multiwall carbon nanotubes or graphene fibers as well as elements in the ambient environment such as moisture to generate such rotational action. The torsional strain, torque, speed and lifetime have been evaluated under various electrochemical conditions to provide insight into the actuation mechanism and performance. Here the most recent advances in artificial muscles based on sheath-run artificial muscles (SRAMs) are reviewed. Finally, the rotating motion of the CNT yarn actuator and the humidity-responsive twisted graphene fibers have been coupled to a mixer for use in a prototype microfluidic system, moisture management and a humidity switch respectively.

Highlights

  • Actuating materials, or ‘arti cial muscles’, continue to attract a great deal of interest because of the need to develop compact and lightweight motor systems for robotics, micro- uidics, medical prosthetics and micro-machines

  • High performance carbon nanotube yarns can be prepared from carbon multiwalled nanotube (MWNT) forests grown by chemical vapor deposition (CVD) using acetylene (C2H2) gas as the carbon precursor

  • Most recently we have reported a new generation of hybrid carbon nanotube yarn arti cial muscles, known as sheath-run arti cial muscles (SRAMs), featuring a sheath around a coiled or twisted yarn, which contracts, or actuates, when heated, and returns to its initial state when cooled

Read more

Summary

Introduction

‘arti cial muscles’, continue to attract a great deal of interest because of the need to develop compact and lightweight motor systems for robotics, micro- uidics, medical prosthetics and micro-machines. High inserted twist results in coiled muscles that can deliver tensile strokes exceeding those of nature's skeletal muscles.[4] More recently a new generation of arti cial muscles was reported based on core–sheath hybrid carbon nanotube yarns or commercially available yarns. Inspired by the initial work with twisted CNT based yarns, researchers have developed high performance torsional and tensile actuators using other materials. Actuator materials based on highly twisted wet-spun graphene bers and hybrid carbon nanotube/graphene bers have been developed recently.[10,11,12,13,14,15,16] Even metallic nanowires from niobium have been formed into twisted yarns that deliver fast and large torsional actuation at low input voltages. We explore the current understanding of the fundamental actuation mechanisms in these systems

Preparation of carbon nanotube yarns
Torsional actuation
Optimal con gurations for torsional actuation
Torsion mechanics analysis of torsional actuation
Torsional actuation performance
Tensile actuation
Optimal con gurations for tensile actuation
Absorption driven tensile actuation in coiled hybrid
Single helix model of torsional and tensile actuation in twisted yarns
Fabrication of graphene ber actuators
Moisture-activated torsional graphene ber actuator
Sheath-run artificial muscles
Applications
Findings
Conclusions and future work

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.