Dan Preston logs in a respectable, nondescript shirt to our video call. His personal style might be on the conventional side, but the Rice University mechanical engineer is here to tell me about his creative new fashion design. His team has created a shiny black jacket that runs logic – without electronics. Notably, the jacket can raise and lower its own hood at the push of a button, and it includes a simple 1-bit memory that stores the state of the hood. Or, as Preston puts it, it’s “a non-electronic, persistent logic in a fabric-based device.”
Here we must emphasize the wildness of this design. The hoodie does not contain an Arduino or any semiconductor chips. It has no batteries. Preston and his team cut pieces of commercial nylon taffeta fabric and glued them together into inflatable pouches about half the size of a business card. They connect the pockets with small soft tubes and embedded them in the jacket. Pressing buttons on the jacket controls the flow of air from a carbon dioxide canister through the bags. The pockets fold and unfold to form creases that either inflate or deflate an airbag in the hood to allow it to rise and fall.
At first glance, the jacket looks more like a bicycle tire than a computer. But you can think of the air-filled pockets on the jacket as analogous to electronic transistors, says Preston. In an electronic circuit, transistors control the flow of electrons, or electric current, based on the voltage across the circuit. “We’re just replacing voltage with pressure, and we’re replacing current with the flow of a liquid, in this case air,” he says.
For example, the team created an airborne EMERGENCY gate. In an electronic circuit, a NOT gate takes an input – say a 1, which corresponds to a high voltage – and changes it to a 0 or a low voltage. In the case of the hoodie, the air going into a bag can be at high pressure and the bag can convert it to low pressure or vice versa. The technology dates back to Cold War defense applications, when engineers developed airborne logic devices because opponents couldn’t jam them with electromagnetic pulses.
“I’m really excited to see people radically pushing the cutting edge when it comes to wearables,” says mechanical engineer Michael Wehner of the University of Wisconsin-Madison, who was not involved in the work. Particularly novel is the team’s use of substance-based and air-based logic, also known as pneumatic logic. Wearables like Fitbit and Apple Watch are typically “modest adaptations of traditional devices,” Wehner says.
The jacket falls into the category of “soft robots”, which are automated, programmable machines made of flexible materials such as rubber, silicone or fabric. In recent years, researchers have started developing soft robots that can potentially work alongside humans. They generally move less precisely than their carbide counterparts, but they have a softer touch. “If you work and a [hard] If a robot hits you, with a bit of luck you’ll end up in the hospital,” says Wehner. “When a soft robot — that big airbag — hits you, everyone laughs and enjoys themselves.”
In other words, soft robots should be easier and safer to integrate into normal human activities. Because Preston’s logic elements are made of fabric, the smart jacket feels more like a regular jacket than a coat stuffed with electronics or other hard components. “People can get used to it very easily and don’t feel like they’re wearing anything strange,” says Wenlong Zhang, a mechanical engineer at Arizona State University who was not involved in the work.
Also, a fabric computer is more resilient than a semiconductor-based one. To test the jacket’s durability, the team slipped a component from several cloth bags into a mesh bag and ran it through the washing machine 20 times. They also hit it with a 2002 Toyota Tacoma pickup – scenarios, “You might expect a traditional garment to see some extremes in its lifetime,” says Preston. The bags still worked. Imagine doing this with an Apple Watch.