A team of researchers led by University of Massachusettes Amherst’s Dr. Trisha Andrew has developed ‘smart’ pajamas embedded with self-powered sensors that provide unobtrusive and continuous monitoring of heartbeat, breathing and sleep posture.
Ordinary-looking pajamas are transformed into ‘smart’ ones with five strategically placed sensors that measure heartbeat, respiration and posture. Image credit: Trisha L. Andrew.
Getting enough quality sleep can help protect people against stress, infections and multiple diseases, such as heart and kidney disease, high blood pressure and diabetes. Quality sleep also increases mental acuity and sharpens decision-making skills. Yet most people do not get enough sleep — or the right kind.
Commercially available electronic bands worn on the wrist give information about heart rate and monitor how much total sleep the wearer gets.
But until now, there has not been anything that a typical consumer could use to monitor posture and respiratory and cardiac signals when slumbering.
“Our smart pajamas overcame numerous technical challenges,” Dr. Andrew said.
“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 ‘Phyjama,’ as Dr. Andrew and colleagues calls it, 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,” Dr. Andrew explained.
“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 has five 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 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 first-of-their-kind patches are used in different parts of the Phyjama so that the researchers can determine sleeping posture.
However, this type of sensor cannot pick up the faint pressure from a beating heart. The triboelectric patch detects quick changes in pressure, such as the physical pumping of the heart, which provides information on heart rate.
The scientists have tested the garment on volunteers and validated the readings from the sensors independently. They estimate the product could be on the market within two years for $100-$200.
They presented their results this week at the ACS Spring 2019 National Meeting & Exposition in Orlando, FL.
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Trisha L. Andrew. Sensing human behavior with smart garments. ACS Spring 2019 National Meeting & Exposition, MPPG 32
