Researchers Develop New Health-Monitoring Sleepwear Named “Phyjamas”

Researchers predict that in years to come, electronically active garments integrated with portable, unobtrusive devices to monitor respiratory rhythm and heart rate while asleep, for instance, will be clinically useful in health care.

Fabric-based pressure sensor combined with a triboelectric sensor. (Image credit: (UMass Amherst/Andrew lab)

Scientists from the University of Massachusetts Amherst have created physiological-sensing textiles that can be stitched or woven into sleep garments, named “phyjamas” by the team.

The health-monitoring sleepwear will be presented by graduate students Ali Kiaghadi and S. Zohreh Homayounfar, together with their professors Trisha L. Andrew, a materials chemist, and Deepak Ganesan, a computer scientist, at the Ubicomp 2019 conference this week in London, United Kingdom. An article describing the study has been selected for publication in the Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies (IMWUT).

The challenge we faced was how to obtain useful signals without changing the aesthetics or feel of the textile. Generally, people assume that smart textiles refer to tightly worn clothing that has various sensors embedded in it for measuring physiological and physical signals, but this is clearly not a solution for everyday clothing and, in particular, sleepwear.

Trisha L. Andrew, Materials Chemist, UMass Amherst

Ganesan stated, “Our insight was that even though sleepwear is worn loosely, there are several parts of such a textile that are pressed against the body due to our posture and contact with external surfaces. This includes pressure exerted by the torso against a chair or bed, pressure when the arm rests on the side of the body while sleeping, and light pressure from a blanket over the sleepwear.”

Such pressured regions of the textile are potential locations where we can measure ballistic movements caused by heartbeats and breathing,” he explains, “and these can be used to extract physiological variables.” The challenge is that these signals could be individually unreliable, specifically in loose-fitting clothing; however, signals from various sensors positioned across different parts of the body can be smartly integrated to obtain a more accurate composite reading.

Andrew, Ganesan, and their team describe that they had to create a number of new concepts to turn their vision into reality. They figured out that no fabric-based techniques exist at present to sense dynamic and continuous changes in pressure, specifically given the small signals that they have to measure.

Therefore, they engineered a new fabric-based pressure sensor and integrated that into a triboelectric sensor—one that is triggered by a change in physical contact—to create a distributed sensor suite that could be incorporate into loose-fitting clothing such as pajamas. In addition, they developed data analytics to fuse signals from various points that took into account the quality of the signal received from every location.

According to the authors, this combination enabled them to sense physiological signals over several different postures. They carried out a number of user studies in both natural and controlled settings and demonstrated that they can extract breathing rate with an error of less than one beat per minute, heartbeat peaks at a higher accuracy, and precisely predict sleep posture.

We expect that these advances can be particularly useful for monitoring elderly patients, many of whom suffer from sleep disorders,” stated Andrew.

Current generation wearables, like smartwatches, are not ideal for this population since elderly individuals often forget to consistently wear or are resistant to wearing additional devices, while sleepwear is already a normal part of their daily life. More than that, your watch can’t tell you which position you sleep in, and whether your sleep posture is affecting your sleep quality; our Phyjama can.

Trisha L. Andrew, Materials Chemist, UMass Amherst

This study was improved by Ganesan and Andrew’s association with UMass Amherst’s Institute of Applied Life Sciences (IALS), which has a focus on transforming life science study into products that enhance human health.

According to Director Peter Reinhart at IALS, “It’s exciting to see the next generation of wearable technology that is zero effort and addresses the issue of comfort and unobtrusiveness head-on. The data generated by fabric-based sensors have the potential to improve health and well-being, and could possibly contribute to the early diagnosis of multiple disorders.”


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