computer interfaced rain jacket
Courtesy of Dan Preston

Forget Silicon. This Computer Is Made of Fabric

The jacket can raise and lower its own hood—without chips or batteries—and might one day help disabled wearers move.

Dan Preston logs in to our video call in a respectable, nondescript button-up shirt. His personal style may lean toward the conventional, but the Rice University mechanical engineer is here to tell me about his creative new fashion design. His team has made a shiny black jacket that performs logic—without electronics. Specifically, the jacket can raise and lower its own hood at the push of a button, and it contains a simple 1-bit memory that stores the state of the hood. Or, as Preston says, it’s “a non-electronic durable logic in a textile-based device.”

Here’s where we need to 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 have cut pieces of commercial nylon taffeta fabric and glued them together to form inflatable pouches about half the size of a business card. Connecting the pouches with small soft tubes, they have embedded them into the jacket. Pressing buttons on the jacket controls the flow of air from a canister of carbon dioxide through the pouches. The pouches fold and unfold to form kinks that either inflate or deflate an airbag in the hood to make it rise and fall.

Courtesy of Dan Preston

At first glance, the jacket seems more like a bike tire than a computer. But you can think of the air-filled pouches 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 in the circuit. “We’re just replacing voltage with pressure, and we’re replacing current with the flow of a fluid, which is air in this case,” he says.

For example, the team created an air-based NOT gate. In an electronic circuit, a NOT gate receives some input—say a 1, corresponding to a high voltage—and changes it to a 0, or low voltage. In the hoodie’s case, the air going into a pouch might be at high pressure, and the pouch can convert it into a low pressure, or vice versa. The technology originates from Cold War defense applications, when engineers designed air-based logic devices because adversaries could not interfere with them using electromagnetic pulses.

“I’m really happy to see people moving radically beyond the cutting edge in wearables,” says mechanical engineer Michael Wehner of the University of Wisconsin-Madison, who was not involved in the work. The team’s use of fabric and air-based logic, also known as pneumatic logic, is particularly novel. Wearables, like the Fitbit and Apple Watch, are usually “modest adaptations of traditional devices,” says Wehner.

The jacket falls under 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 begun designing soft robots to potentially work alongside humans. They generally move with less precision than their hard metal counterparts, but they have a gentler touch. “If you’re working and a [hard] robot hits you, you go to the hospital if you’re lucky,” says Wehner. “If a soft robot—this big airbag—hits you, everyone laughs and has a good time.”

Courtesy Dan Preston

In other words, soft robots should more easily and safely integrate into regular human activity. Because Preston’s logic elements are made of fabric, the intelligent jacket feels more like a regular one than a coat filled with electronics or other hard components. “It is very easy for humans to adapt to it and not feel like they are wearing something weird,” says mechanical engineer Wenlong Zhang of Arizona State University, who was not involved with the work.

In addition, a fabric computer is more resilient than a semiconductor-based one. To test the jacket’s robustness, the team placed a component made of several fabric pouches in a mesh bag and ran it through a washing machine 20 times. They also ran it over with a 2002 Toyota Tacoma pickup truck—scenarios “you might expect a traditional piece of clothing to encounter at some of the extremes in its lifetime,” says Preston. The pouches still worked. Imagine doing that to an Apple Watch.

While the jacket is largely a demonstration of the feasibility of clothing-based logic, the team also imagines it could aid people with disabilities who have difficulty raising or lowering a hood. In addition to the jacket, they made a shirt that can help someone lift their arm at the shoulder joint. The shirt contains air pouches on the torso that pump an accordion-like bellows under the arm. “Up to a quarter of people in the United States report some difficulty lifting a 10-pound object,” says Preston.

Courtesy of Dan Preston

To prototype the jacket, the team purchased 100 meters of nylon to work with. It may seem like a large quantity of fabric, but suppliers usually prefer to sell at least a kilometer at a time, says materials scientist Vanessa Sanchez of Stanford, a member of Preston’s team. They weren’t accustomed to the academics’ meager needs. “Often, people are like, ‘Oh, your quantity is way too low,’” says Sanchez. “This is a practical challenge. We might get something that works really well, but we can only get a sample every few months. I [have to] then call them five times and beg.”

But the team hopes to scale up later. Preston says they are in the early stages of forming a company to make the technology available to consumers. They would also like to test the safety of these garments in clinical trials so that people can use them in medical settings.

So far, the logic that the jacket can perform is simple. But Preston’s team has designed the components so that future devices can sequentially combine them to perform more complicated computation tasks. For example, a future jacket could contain a temperature sensor, and the garment could incorporate that sensor measurement into its actions. “We can emulate any of the functionality of an electronic computer,” says Preston. “Granted, it might take a little bit longer to do it, but it’s physically possible.”

The existing jacket can perform one logical operation per second, compared to the more than a billion operations per second typical of a home computer, says Preston. In practice, this means the jacket can only execute short command sequences. Due to the speed of the logic, along with some other engineering challenges, Zhang says he thinks it’ll take five to 10 years for these textile-based robots to reach commercial maturity.

In the future, Preston’s team plans to do away with the carbon dioxide canister, which is impractical. (You have to refill it like you would a SodaStream.) Instead, his team wants to just use ambient air to pump up the jacket. As a separate project, the team has already developed a foam insole for a shoe that pumps the surrounding air into a bladder worn around the waist when the wearer takes a step. They plan to integrate a similar design into the jacket.

Preston also envisions clothing that senses and responds to the wearer’s needs. For example, a sensor on a future garment could detect when the wearer is beginning to lift their arm and inflate without any button-pressing. “Based on some stimulus from the environment and the current state, the logic system can allow the wearable robot to choose what to do,” he says. We’ll be waiting for this fashion trend to blow up.