Wobbly gel mat trains muscle cells to work together

They next grew a carpet of muscle cells on the gel’s surface and activated the magnet’s motion. They sandwiched four magnetic bars, each spaced slightly apart, between two layers of hydrogel — a material that is typically used to culture muscle cells. Finally, the researchers placed an external magnet on a track beneath the gel mat and programmed the magnet to move back and forth. The muscle cells that the team used in this study were genetically engineered to contract in response to blue light. Typically, muscle cells in the body contract in response to a nerve’s electrical pulse.