ANDRZEJ KRAUZEIn 2013, bioengineer Wen Wang, then a research scientist at MIT, attended a talk on how Bacillus spores shrink in response to falling relative humidity. The research, published the following year in Nature Nanotechnology (9:137-41), focused on using this property to extract energy, but it gave Wang another idea: What if she could use shape-shifting bacteria to develop a material that would ventilate upon sensing the sweat of its wearer? “Humans are a natural source of humid air,” she says. “We thought maybe we can do something related to garments.”
She teamed up with her friend and colleague Lining Yao, also a researcher at MIT’s Media Lab, and began testing what caused the spores to change shape. Through a process of elimination, the team found that it was changes to the proteins inside the spores that contributed the most to the volume change, though DNA and polysaccharides also shifted configuration in response to changes in humidity. Sure enough, attaching pure bacterial protein to a fabric caused the material to become moisture sensitive. “Imagine you have a double-layer system: the top layer is the protein layer; the bottom layer is the fabric layer,” Wang explains. “When the top layer starts to shrink [in response to dry conditions], the whole thing bends up.”
Then came the challenge ...
