Optically controllable muscle for cell-based microdevice

Biomicrodevices incorporating biological components such as tissues, cells and biomolecules have raised much attention for novel engineering devices. Particularly, the muscle-powered microactuator driven by biochemical energy reaction would also save energy, resource and space. With these advantages, conventionally, contractile muscles have been applied to engineered microdevices using electrical field stimulation. Electrical field stimulation is a simple method to control the temporal pattern of contractile activity. However, it is generally nonuniform and many unexpected muscle cells are stimulated simultaneously. To improve both the spatial and temporal resolutions, we made photosensitive skeletal muscle cells from murine C2C12 myoblasts, which express light-gated ion channel, channelrhodopsin (ChR). The light pulse depolarized the membrane potential of a ChR-expressing muscle and eventually evoked an action potential. It also induced a twitch-like contraction in a concurrent manner with a given pattern of LED pulses. This technique would have many applications in the bioengineering field, such as wireless drive of muscle powered actuators/microdevices.