Working up a good sweat is often considered a benchmark for having had an effective workout. But let’s be honest, not everyone likes getting hot and sweaty.
However, engineers at MIT have come to your rescue and designed a workout suit that responds to your body heat.
The clothing, made from latex, is covered with thumbnail- to finger-sized ventilating flaps that open and close depending on how much heat your body puts out. But what’s controlling the flaps isn’t something you’ll find weaved into your usual workout gear- it’s bacteria.
Bacteria and other biological cells can respond to humidity, expanding when it’s high and shrinking as the air gets drier. The researchers found that microbial response to changes in humidity was strong enough to open pore-like holes in a running top, perfect for when athletes start to break a sweat.
Wen Wang, an MIT bioengineer, headed up the biotechnology and materials science for the study. Wang and her team explored a number of different applications before focusing on clothing.
With textiles, Wang and her team found the optimal construction was a layer of latex sandwiched by two thin layers of bacterial cells, each 1 to 5 microns thick, around the
diameter of a red blood cell and 1/15th the width of a human hair. These were formed into flaps, and attached to the back of a workout garment. When the wearer sweats, the cells on the outside remain the same, but the cells on the side facing the body absorb moisture and expand, forcing the flaps open.The MIT Media Lab’s bioLogic group, which Wang and her collaborators are part of, has been building this sort of clothing for a couple of years. But Wang felt there was room for improvement; initially, they used a bacteria called Bacillus subtilis natto, better known as the main component of the gooey, stringy, pungent Japanese food called nattō.
“Some people might be afraid that the bacteria may contaminate my home, or my kids,” says Wang, though she emphasizes the microbe’s safety. “Our skin is not a vacuum. If you have no bacteria on it, it will have some bad bacteria on it. So in the future, we also want to combine microbiome technology with our current design to make a microbiome-carrying garment.”
The team also integrated the moisture-responsive fabric into a rough prototype of a running shoe. Where the bottom of the foot touches the sole of the shoe, the researchers sewed multiple flaps, curved downward, with the cell-lined layer facing toward — though not touching — a runner’s foot.
As with the workout suit, the flaps on the running shoe opened and lit up when researchers increased the surrounding humidity; in dry conditions the flaps faded and closed.
Going forward, the team is looking to collaborate with sportswear companies to commercialize their designs, and is also exploring other uses, including moisture-responsive curtains, lampshades, and bedsheets.
“We are also interested in rethinking packaging,” Wang says. “The concept of a second skin would suggest a new genre for responsive packaging.”
“This work is an example of harnessing the power of biology to design new materials and devices and achieve new functions,” says Xuanhe Zhao, the Robert N. Noyce Career Development Associate Professor in the Department of Mechanical Engineering and a co-author on the paper. “We believe this new field of ‘living’ materials and devices will find important applications at the interface between engineering and biological systems.”
