Artificial Muscles Made of Proteins
Artificial synaptic memory material testing showing memristive switching behavior characterizationArtificial Muscles
Researchers from Germany have developed artificial muscles that contract autonomously using natural proteins. The muscle contraction is regulated by a change in temperature and pH. The muscle’s contraction is fueled by chemical energy. “Our artificial muscle is still a prototype,” says Dr. Schiller from the University of Freiburg’s. “However, the high biocompatibility of the material and the possibility of adjusting its composition to match particular tissue could pave the way for future applications in reconstructive medicine, prosthetics, pharmaceutics, or soft robotics.” A highly accelerated stress test might reveal its potential.
Figure: Artificial muscles based on elastin protein Source: HDT GlobalElastin as a basis for the muscles.
The artificial muscles are based on elastin. Elastin is an extracellular matrix protein that lends elasticity and resilience to tissues such as the arteries, lungs, tendons, skin, and ligaments. Using elastin as a model, researchers cultivated two elastin-like proteins in a metrology lab. One type responds to the changes in pH, the other to temperature. The researchers combined the two proteins into a bilayered material using photochemical cross-linking.
The pH and the temperature regulate muscle contraction:
Researchers used sodium sulfite to fuel muscle contraction. The chemical energy is converted into mechanical energy due to the non-equilibrium states of the material.
- pH is used to regulate the rhythm of contraction
The muscle can contract autonomously in a cyclical manner due to oscillating chemical reactions in which the pH changes in cycles. The contraction mimics the oscillating chemical reactions
- The temperature is used to switch the contraction on or off.
The oscillating chemical reaction started at a temperature of around 20 °C, and the material began to make rhythmic movements. Using this fact, the researchers could turn the contractions on and off by changing the temperature. This system could be programmed to respond to another stimulus.
“Since it is derived from the naturally occurring protein elastin and is produced by us through biotechnological means, our material is marked by a high sustainability that is also relevant for technical applications,” explains Schiller. “In the future, the material could be developed further to respond to other stimuli, such as the salt concentration in the environment, and to consume other energy sources, such as malate derived from biomass.”
