Researchers have developed pajamas embedded with self-powered sensors that provide continuous monitoring of heartbeat, breathing, and sleep posture. The researchers say these “smart” garments could give ordinary people, as well as clinicians, useful information to help improve sleep patterns.
The researchers presented their results at the American Chemical Society (ACS) Spring 2019 National Meeting & Exposition.
“Our smart pajamas overcame numerous technical challenges,” says Trisha L. Andrew, PhD, who led the team, in a release. “We had to inconspicuously integrate sensing elements and portable power sources into everyday garments, while maintaining the weight, feel, comfort, function, and ruggedness of familiar clothes and fabrics. We also worked with computer scientists and electrical engineers to process the myriad signals coming from the sensors so that we had clear and easy-to-understand information.”
The key to the smart pajamas is a process called reactive vapor deposition. “This method allows us to synthesize a polymer and simultaneously deposit it directly on the fabric in the vapor phase to form various electronic components and, ultimately, integrated sensors,” Andrew says. “Unlike most electronic wearables, the vapor-deposited electronic polymer films are wash-and-wear stable, and they withstand mechanically demanding textile manufacturing routines.”
The “Phyjama,” as the University of Massachusetts, Amherst team calls it, has 5 discrete textile patches with sensors in them. The patches are interconnected using silver-plated nylon threads shielded in cotton. The wires from each patch end up at a button-sized printed circuit board placed at the same location as a pajama button. Data are wirelessly sent to a receiver using a small Bluetooth transmitter that is part of the circuitry in the button.
The garment includes two types of self-powered sensors that detect “ballistic movements,” or pressure changes. Four of the patches are piezoelectric. They detect constant pressures, such as that of a bed against a person’s body. These patches are used in different parts of the Phyjama so that the researchers can determine sleeping posture. The triboelectric patch detects quick changes in pressure, such as the physical pumping of the heart, which provides information on heart rate. This is the first time such a sensor has been shown to detect tiny ballistic signals from the heart.
Andrew’s team has tested the garment on volunteers and validated the readings from the sensors independently. They also have applied for patents on the Phyjama. After Andrew partners with a manufacturer, she estimates the product could be on the market within two years for $100-$200.
Currently, the team is working on extending the technology to wearable electronic sensors that detect gait and send feedback to a monitor to help prevent falls. This application could find use in settings such as nursing homes and retirement centers, Andrews says.
Photo courtesy of Trisha L. Andrew