When it’s hot inside, you can open a window in the hope that it cools off. However, as an athlete, there is only so much you can take off until it is frowned upon, not to mention the fact that most athlete clothes are designed in such a way that they increase performance. In an attempt to keep athletes decent, but still providing them with often much needed ventilation, researchers at MIT created a breathable workout suit, called bioLogic, with ventilation flaps that are lined with live microbial cells that shrink and expand in response to changes in humidity.

In nature, living things or their components react when there is a change in humidity (pinecones, for example). The aim of the project was to utilise this property as building blocks to construct moisture responsive fabrics.

The microbial cells act as tiny sensors and actuators. They drive the flaps, which range from thumbnail- to finger-sized, open when the athlete is working out and thus sweating. When the body cools off, the flaps close again.

The researchers say that moisture-sensitive cells require no additional elements to sense and respond to humidity. The microbial cells they used are also proven to be safe to touch and even to consume. In addition, cells can be prepared quickly and in vast quantities, to express multiple functionalities in addition to moisture response.

To demonstrate this last point, the researchers engineered moisture-sensitive cells to not only pull flaps open but also light up in response to humid conditions.

The researchers first worked with the most common non-pathogenic strain of E. coli, which was found to swell and shrink in response to changing humidity. They further engineered the cells to express green fluorescent protein, enabling the cell to glow when it senses humid conditions.

They then used a cell-printing method they had previously developed to print E. coli in parallel lines onto sheets of rough, natural latex, creating two-layer structures. When placed on a hot, dry surface, the overlaying latex layer curls up, while it flattens out when exposed to steam.

The researchers worked the bioLogic fabric into a wearable garment, designing a running suit with cell-lined latex flaps patterned across the suit’s back. They tailored the size of each flap, as well as the degree to which they open, based on previously published maps of where the body produces heat and sweat.

The researchers have also fashioned a running shoe with an inner layer of similar cell-lined flaps to air out and wick away moisture.

Images: Hannah Cohen / Chengyuan Wei / Chin-Yi Cheng