Performance of silk‐polypyrrole bilayer actuators under biologically relevant conditions

Abstract

Biocompatible actuators that are capable of controlled movement and can function under biologically relevant conditions are of significant interest for biomedical applications. Previously, we have demonstrated that a composite material of silk biopolymer and the conducting polymer poly(pyrrole) (PPy) can be formed into a functional bilayer bending actuator. Further, these silk-PPy composites can generate forces comparable to human muscle (>0.1 MPa) making them ideal candidates for interfacing with biological tissues. Here, we explore the performance of these silk-PPy composite bilayer actuators under biologically relevant conditions including exposure to proteins, serum, enzymes, and biologically relevant temperatures. Free-end bending actuation performance, current response, force generation, and mass degradation under these conditions were investigated. We find that under the conditions tested here, the performance of our silk-PPy composites is sensitive to both protein serum and enzyme type, as well as to the temperature at which the devices are actuated. However, the silk-PPy actuators retained their functionality under all conditions tested, demonstrating the ability to bend, generate forces, and conduct currents at comparable levels to devices tested under standard operating conditions. The results suggest that our silk-PPy actuators are promising candidates for implantation in vivo and for interfacing with biological systems.

Smart Film Actuators for Biomedical Applications

“…Biochemical-responsive SFAs use specific recognition interactions between functional materials and target biomolecules, such as enzymes or ions, as the actuating trigger to complete complex tasks. [170,171]…”

Multi-strand Fibers with Hierarchical Helical Structures Driven by Water or Moisture for Soft Actuators

“…For a fiber-based silk actuator, which exhibits excellent mechanical properties and has a strength of 400 MPa, its long response time limits its application. 36 Thus, it is critical to design an actuator that can realize fast execution speed in response to external stimuli with high strength and good toughness and exhibit large load capability during spontaneous execution. Carboxyl methyl cellulose (CMC), a bio-based waterresponsive material, which has been widely studied as a membrane-based and hydrogel-based actuator, has not yet been introduced into fiber-based actuators.…”

“…However, the poor responsiveness to the humidity of the actuator with a maximum speed of 7.5 rpm poses a challenge. For a fiber-based silk actuator, which exhibits excellent mechanical properties and has a strength of 400 MPa, its long response time limits its application . Thus, it is critical to design an actuator that can realize fast execution speed in response to external stimuli with high strength and good toughness and exhibit large load capability during spontaneous execution.…”

Bioinspired polypyrrole based fibrillary artificial muscle with actuation and intrinsic sensing capabilities

“…The motivation is the disruptive potential for applications of devices with complex actuation functions, similar to those of living organisms. A notable example of this is represented by the field of artificial muscle research where devices fabricated using classical architectures 1 – 3 are replaced by faster responding, highly flexible and mechanically stable while simultaneously sensitive materials 4 , 5 seek to closely mimic the natural muscles functions. Consequently, various stimuli responsive components were integrated in bioinspired devices such as conducting polymers 6 , 7 , graphene 8 , carbon nanotubes 9 , dielectric elastomers 10 , etc.…”