The modern world is one of inexpensive, connected devices and sensors that can provide us with endless insights about ourselves and the world around us. It no longer evokes great wonder in us to learn of a new wearable device that can monitor our physiological signals throughout the day. Despite the availability of numerous gadgets that can track our health and give us advance warning about possible problems before they ever occur, relatively few people actually make use of these technologies on any sort of regular basis. Given the obvious benefits that these wearables can offer to us, why is their level of adoption so minimal?
A strong argument could be made that the utility of these devices is overshadowed by the inconvenience and discomfort of wearing them. Especially in the case of people who believe themselves to be perfectly healthy, these drawbacks simply outweigh the perceived benefits. This state of affairs may be beginning to change, thanks in part to the efforts of a team of researchers at Osaka Prefecture University. They have paved a path forward for developing comfortable, wearable sensors that conform to the body by employing techniques borrowed from the ancient Japanese art of paper cutting, called kirigami.
Sensor structure and application (📷: Y. Xuan et al.)
The team applied their methods in building a bendable, stretchable sensor that is capable of collecting electrocardiographic data. By cutting polyethylene terephthalate (PET) in precise ways, the normally stiff material is softened to the point that it can comfortably conform to surfaces of the body. Further, since kirigami involves cutting holes into the substrate, the technique lends itself to creating a breathable sensor, which improves both comfort and hygiene.
By adding silver electrode traces to the PET, a sensor is created that is able to capture signals from the wearer’s heart by attaching the device to the body like a bandage. The tight conformation of the device to the body also allows for better signal to noise ratios to be achieved, which improves the quality of the data that is gathered. Rather than sacrificing quality to improve comfort, kirigami techniques actually improve wearability and quality at the same time.
Sensor data collected during various activities (📷: Y. Xuan et al.)
A study was conducted by the researchers to better understand the optimal size of an electrocardiographic sensor, and the ideal spacing between electrodes. They found that an overall size of 200 square millimeters, with 1.5 centimeters between electrodes, provided sufficient signal from the heart to enable use of the sensor with a companion smartphone app. They also found that their sensor was able to provide accurate data when used by multiple people as they went about their everyday activities, like walking, working, or resting.
Considerable work was done to prove the utility and accuracy of their wearable electrocardiogram device, but the team intends to see if they can extend their techniques to collect other types of physiological data in the future. They are hoping to collect multiple types of data, and conduct medical trials to help them understand if they can provide early diagnosis of disease. They also intend to further improve the stability of sensor measurements to allow for practical applications of their methods, outside of the research lab.