AMHERST, Mass. Inspired by nature's ability to shape a petal, and building on simple techniques used in photolithography and printing, researchers at the University of Massachusetts Amherst have developed a new tool for manufacturing three-dimensional shapes easily and cheaply, to aid advances in biomedicine, robotics and tunable micro-optics.
Ryan Hayward, Christian Santangelo and colleagues describe their new method of halftone gel lithography for photo-patterning polymer gel sheets in the current issue of Science. They say the technique, among other applications, may someday help biomedical researchers to direct cells cultured in a laboratory to grow into the correct shape to form a blood vessel or a particular organ.
"We wanted to develop a strategy that would allow us to pattern growth with some of the same flexibility that nature does," Hayward explains. Many plants create curves, tubes and other shapes by varying growth in adjacent areas. While some leaf or petal cells expand, other nearby cells do not, and this contrast causes buckling into a variety of shapes, including cones or curly edges. A lily petal's curve, for example, arises from patterned areas of elongation that define a specific three-dimensional shape.
Building on this concept, Hayward and colleagues developed a method for exposing ultraviolet-sensitive thin polymer sheets to patterns of light. The amount of light absorbed at each position on the sheet programs the amount that this region will expand when placed in contact with water, thus mimicking nature's ability to direct certain cells to grow while suppressing the growth of others. The technique involves spreading a 10-micrometer-thick layer (about 5 times thinner than a human hair) of polymer onto a substrate before exposure.
Areas of the gel exposed to light become crosslinked, restricting their ability to expand, while nearby unexposed areas will swell like a sponge as they absorb w
|Contact: Ryan Hayward|
University of Massachusetts at Amherst