Researchers have developed pyjamas embedded with self-powered sensors that provide unobtrusive and continuous monitoring of heartbeat, breathing and sleep posture — all factors that play a role in how well a person slumbers.

The garment called “Phyjama” could give ordinary people as well as clinicians useful information to help improve sleep patterns.

“Our smart pyjamas overcame numerous technical challenges. 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,” said lead author Trisha L. Andrew from the University of Massachusetts, Amherst.

The key to the smart pyjamas is a process called reactive vapour deposition, according to the findings presented at the American Chemical Society (ACS) Spring 2019 National Meeting and Exposition.

“This method allows us to synthesize a polymer and simultaneously deposit it directly on the fabric in the vapour phase to form various electronic components and ultimately integrated sensors,” said Andrew.

“Unlike most electronic wearables, the vapour-deposited electronic polymer films are wash-and-wear stable and they withstand mechanically demanding textile manufacturing routines,” he added.

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 pyjama 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 like that of a bed against a person’s body.

The triboelectric patch detects quick changes in pressure, such as the physical pumping of the heart which provides information on heart rate, the researcher said.

For the study, the team tested the garment on volunteers and validated the readings from the sensors independently.