Robots have long been seen as a bad bet for Silicon Valley investors—too complicated, capital-intensive and "boring, honestly," says venture capitalist Modar Alaoui.

Biological muscles act as flexible actuators, generating force naturally and with an impressive range of motion. Unsurprisingly, scientists and engineers have been striving to build artificial muscles that mimic these abilities. A new review study, published in Nature, takes a deep dive into recent developments surrounding fiber-type artificial muscles, one of the most life-like types of artificial muscles developed so far.