One-volt-driven superfast polymer actuators based on single-ion conductors

Abstract

The key challenges in the advancement of actuator technologies related to artificial muscles include fast-response time, low operation voltages and durability. Although several researchers have tackled these challenges over the last few decades, no breakthrough has been made. Here we describe a platform for the development of soft actuators that moves a few millimetres under 1 V in air, with a superfast response time of tens of milliseconds. An essential component of this actuator is the single-ion-conducting polymers that contain well-defined ionic domains through the introduction of zwitterions; this achieved an exceptionally high dielectric constant of 76 and a 300-fold enhancement in ionic conductivity. Moreover, the actuator demonstrated long-term durability, with negligible changes in the actuator stroke over 20,000 cycles in air. Owing to its low-power consumption (only 4 mW), we believe that this actuator could pave the way for cutting-edge biomimetic technologies in the future.

Multivalent ion conduction in solid polymer systems

“…While solvents and plasticizers can be added to polymer electrolytes to depress Tg or enhance ion dissociation, the addition of mobile small molecules introduces stability concerns and alters the mechanism of ion transport. [45][46][47][48] Ion conduction within such gel electrolytes is dominated by vehicular transport of solvent molecules rather than direct interaction with the polymer. Herein we focus on dry solid multivalent ion conducting polymers, where conduction mechanisms are directly tied to interactions between the ions and polymer host.…”

Stretchable organic optoelectronic sensorimotor synapse

“…EPSCs from the organic optoelectronic synapse were converted to voltage signals to operate our fabricated polymer actuator. The low voltage–driven polymer actuator was composed of imidazole (Im)–doped poly(styrenesulfonate- b -methylbutylene) (PSS- b -PMB) block copolymers, a zwitterion of 3-(1-methyl-3-imidazolium) propanesulfonate, and CNT electrodes that had been fabricated as reported previously ( 16 ). S/D voltage was applied to the source electrode of the artificial synapse, rather than to the drain electrode (fig.…”

“…Here, we aim to demonstrate an organic optoelectronic sensorimotor artificial synapse that is based on a stretchable organic nanowire synaptic transistor (s-ONWST) to perceive and propagate optical sensory inputs and to generate informative synaptic responses and subsequent motor outputs. Specifically, this sensorimotor synapse combined with a photodetector converts patterned optical stimuli into potentiated synaptic responses through the s-ONWST to conduct optical wireless communication of light fidelity and forms an artificial neuromuscular junction to activate artificial muscle actuator with biomimetic muscular contraction mechanism, which cannot be achieved by conventional direct operation of the artificial muscle actuator ( 16 , 17 ). We believe that our organic optoelectronic sensorimotor synapse would open a new era of bioinspired electronics for next-generation prosthetics and neurorobotics.…”

Artificial muscles driven by the cooperative actuation of electrochemical molecular machines. Persistent discrepancies and challenges

“…In addition electro-mechanical actuators, as solid-state inorganic physical actuators responding to electric fields and not including any chemical reaction, have been developed for over one century. During the last 25 years the field of the electro-chemomechanical polymeric actuators (involving chemical reactions) grew in parallel to that of the electro-mechanical polymeric actuators (dry or gels, but never including chemical reactions) [78][79][80][81]. The actuation of the electromechanical actuators, that means the generated strains and forces, are proportional to the applied electric field: to E 2 for electrostrictive polymers; to E, for piezoelectric or ferroelectric polymers, for electrokinetic polymeric gels (electrophoretic or electroosmotic) and for polymeric solutions of salts in solid polymers (coulombic).…”