Smart Printed Sensors Aim at Movement-Monitoring Wearables

So far wearable technology is being designed with utility generally winning over aesthetics or comfort. But recent research from Fraunhofer Institute for Silicate Research (ISC) could change all that with a new transparent sensor material that can be printed with simple manufacturing, offering a cost-effective way to integrate the two into a versatile thin film.

The German research institution, working with Fraunhofer Institute for Silicon Technology (ISIT) and industry project partners, is developing the new sensor technology in a prototype shirt—called the “MONI” shirt—that is designed to monitor a person’s movement sequences.

The project is in its early stages. The first step involved Fraunhofer ISC developing piezoelectric polymer sensor printing pastes that are free from toxic solvents, while Fraunhofer ISIT provided the evaluation electronics. The next steps will include field tests on several types of textiles and applications, further optimization of the electronics, and wear and washability tests, researchers said.

Researchers at Germany’s Fraunhofer ISC have developed transparent sensor material that is being developed into a prototype shirt that can be used to monitor a person’s body movements. They said the material can be printed and used in wearable technology for a number of healthcare and other applications.
(Source: K. Selsam-Geißler, Fraunhofer ISC)

The difficulty in integrating sensors and material is not the actual design but making it cost-effective enough for mass production, according to Fraunhofer researchers. The new material uses a simple screen printing process to apply the sensor pastes onto textile fabrics or plastic films, making manufacturing a simple, two-step process, they said.

That process involves first printing the pattern, after which the sensors are subjected to an electric field, which makes the piezoelectric polymers align to adopt the targeted pressure sensitivity. The resulting sensor material is transparent and flexible, offering more freedom of design in color and form for textiles and garments, researchers said.

Another bonus for the printed sensors is their incredibly small size — much thinner than a human hair — making them almost imperceptible to the wearer when embedded in a garment, according to researchers. Moreover, they aren’t hampered by the addition of a battery because they harvest energy from the body movements that they monitor for their power.

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Researchers envision a number of applications for the printed sensor material, with healthcare naturally being a good fit for numerous new solutions. They suggest the MONI shirt could be used to monitor the body signals of patients, particularly in an assisted-living environment, in which patients may have difficulty performing every-day movements.

Using the shirt could alert to staff to failure and allow them to respond quicker. Monitoring the movement of infants also could be an application for the shirt, among other preventative-health applications, researchers said.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 15 years. She has lived and worked as a professional journalist in Phoenix, San Francisco, and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.