Thermally actuated hydrogel bead based braided artificial muscle

Abstract

Braided (McKibben) artificial muscles are one of the most attractive biomimetic actuators since they exhibit similar static and dynamic performance to skeletal muscles. One disadvantage of these systems, when intended for portable applications, is the need for a compressor or pump to provide pressurised fluid for muscle activation. An alternative is to use an expandable material, such as a hydrogel. This work investigates the development of hydrogel-based braided artificial muscles which can produce mechanical work through controlled hydrogel swelling in the presence of water. Hydrogel bead-filled braided meshes were prepared where no internal bladder was needed; since the bead size was larger than the holes in the braided mesh. A spring test method was introduced to measure force generation and strain developed by the braided mesh when the thermo-responsive gel was cooled from 60 °C to 5 °C-8 °C. Reducing the temperature resulted in hydrogel swelling and braided mesh length contraction due to the internal pressure generated. Blocked forces and actuation free strokes of 5-6 N and 7%-8% were observed, respectively. A long response time was the limiting factor of these actuators due to the slow diffusion properties of the hydrogel.

A macroporous smart gel based on a pH-sensitive polyacrylic polymer for the development of large size artificial muscles with linear contraction

“…Artificial muscle can also be made of a gel sample inserted into a macroscopic system inspired by pneumatic soft robotics [39][40][41] . The gel act as the pressurized fluid for pneumatic muscle: when the gel swells, it applies a pressure on the walls of the soft muscle inducing its displacement.…”

“…Only few prototypes of muscle integrate a porous material [39][40][41]48,63,64 . Tondu et al 40,41 built a muscle with large size and high strength based on porous gel.…”

Characterization of Fluidic-Barrier-Based Particle Generation in Centrifugal Microfluidics

“…Particles made up of natural polymers, such as alginate, chitosan, and gelatin, have found a wide range of applications in the food, cosmetic, biomedicine, agriculture, and pharmaceutical industries due to their abundance, biodegradability, low toxicity, high binding capacity to specific chemical species, and biocompatibility, and their ability to adsorb or release molecules in response to external stimuli. They have been used extensively in drug delivery [11], e.g., encapsulation of islet cells capable of releasing insulin [12,13]; biosensors [14] and actuators [15]; scaffolds for cell culture in tissue engineering [16][17][18]; sorbents [19]; and encapsulation of enzymes and cells [20,21]. Different structures of microparticles are paving the way to a wide variety of applications.…”

Self‐crosslinked poly‐L‐ornithine and poly‐L‐arginine networks: Synthesis, characterization, pH‐responsibility, biocompatibility, and AIE‐functionality

“…10 The flexibility of hydrogels is similar to biological tissues and reduces the material's stimulation on surroundings, which makes hydrogel an ideal biological material. Stimulus-responsive hydrogels have been extensively applied as biosensors for detecting RNA, 11 artificial muscles for the rehabilitation of sports injuries, 12 and controllable drug delivery carriers for disease treatment. 13,14 The mechanism of pH response is mostly related to the pendant groups on the polymer network.…”