Bending 3-D Microshapes With Light

A twist on a long-used printing technique allows researchers to use photolithography to make complex microscale 3-D shapes. Researchers in Ryan Hayward and Christian Santangelo’s research groups at the University of Massachusetts, Amherst (U.S.A.), demonstrated using halftone gel lithography with UV light to phototransfer patterns onto flat polymer gel sheets. The gel swells and contracts with changing temperatures. The pattern of dots changes the amount of expansion, resulting in internal stresses that are relieved by bending out of the plane of the sheet (Science 335, 1201). The technique could be used in bioengineering to build devices that change shape.