Biofabrication by Ritu Raman

Author:Ritu Raman [Raman, Ritu]
Language: eng
Format: epub
Tags: Life Sciences, ethics, Biomedical, biology, Technology & Engineering, science, Bioengineering; Biomedical Engineering; Biomaterials; Biotechnology; Bioinspired Materials; Building with Biology; Tissue Engineering; Regenerative Medicine; Organ-on-a-Chip; Lab-Grown Meat; Medical Implants; Bioethics; Robots; Soft Robots; Biorobotics; Bioenergy; Cell Culture
ISBN: 9780262542968
Google: DOY9EAAAQBAJ
Publisher: MIT Press
Published: 2021-09-14T00:25:25.614523+00:00

Part-biological and part-synthetic biohybrid machines could augment the existing tools and technologies we rely on to improve human health, productivity, and quality of life.

The first studies to investigate this idea relied on directly removing intact living muscle tissue from an animal, coupling it to a robot skeleton made of a synthetic material, and using it to power actuation of the skeleton. A pioneering study in this field, performed by Hugh Herr and Robert Dennis in 2004, tested this approach for designing a biohybrid robot.3 The team extracted two skeletal muscles with intact tendons from frogs and sutured the tendons to either side of a thin ellipse-like substrate made of PDMS and other polymers. In the body, skeletal muscle receives an electrical impulse from motor neurons that tells it when to contract. To replicate this nerve signal, the researchers designed an on-board electrical stimulator that drove current through wires that were wrapped around each muscle. The resulting biohybrid robot was placed in a watertight tank containing Ringer’s solution, a mixture of several types of salts dissolved in water that is often used to preserve tissues or organs extracted from living animals. Electrical stimulation of the muscles using the on-board stimulator made the robot swim around the tank, with a speed that could be tuned by optimizing the rate and degree of electrical stimulation.

While this was a fascinating demonstration and a critical first step toward proving that robots could be powered by biological tissues, using muscle tissue directly removed from animals is not an ideal approach for a few reasons. There is a significant amount of variation between individual animals in a species, so the exact size of the muscle or force generated by the muscle would differ widely between engineered devices depending on which animal supplied the tissue. Moreover, building each device would require sacrificing an animal, which raises ethical concerns as well as sustainability concerns. Being able to biofabricate muscle actuators in the lab to power biohybrid robots would mitigate these concerns and would also provide greater flexibility and control over the size, shape, and functional output of biological actuators.

In 2007, Kevin Kit Parker’s lab took a significant step toward this goal by exploring the use of biofabricated cardiac muscle thin films as actuators.4 While the basis of cardiac muscle contraction is also electrical, those electrical signals are not consciously generated by our nervous system but rather spontaneously generated by the heart’s pacemaker, known as the SA node. Another important difference between cardiac and skeletal muscle is that cardiac muscle cells (cardiomyocytes) are electrically connected to one another, to ensure that they beat in synchrony. When you consider that cardiac muscle has evolved to keep our hearts beating, you can see why contraction occurring at the same time throughout large portions of the tissue is critically important for healthy biological function. Knowing these underlying principles of how cardiac muscle is organized and controlled, Parker’s group decided to make a swimming robot powered by cardiomyocytes.

The team manufactured thin flexible films (less

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