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Little ‘toilet paper’ sensor detects heartbeats and blinks

Engineers used tissue paper—similar to toilet tissue—to make a new kind of wearable sensor that can detect a pulse or a blink of an eye.

The sensor, which is light, flexible, and inexpensive, could be used for health care, entertainment, and robotics, researchers say.

Tearing tissue paper that’s loaded with nanocomposites and breaking the paper’s fibers makes the paper acts like a sensor. It can detect a heartbeat, finger force, finger movement, eyeball movement, and more, says Jae-Hyun Chung, an associate professor of mechanical engineering at the University of Washington and senior author of the paper in Advanced Materials Technologies.

“The major innovation is a disposable wearable sensor made with cheap tissue paper. When we break the specimen, it will work as a sensor.”

The small, Band Aid-sized sensors could have a variety of applications in various fields, researchers say. For example, monitoring a person’s gait or the movement of their eyes can be used to inspect brain function or a game player’s actions. The sensor could track how a special-needs child walks in a home test, sparing the child the need for hospital visits. Or the sensors could be used in occupational therapy for seniors.

“They can use these sensors and after one-time use, they can be thrown away,” Chung says.

For the study, scientists doused tissue paper with carbon nanotube-laced water. Carbon nanotubes are tiny materials that create electrical conductivity.

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Each piece of tissue has both horizontal and vertical fibers, so when the paper is torn, the direction of the tear informs the sensor of what’s happened. To trace eye movement, they’re attached to a person’s reading glasses.

For now, the work has only taken place in a laboratory. Researchers are hoping to find a suitable commercial use. A provisional patent was filed in December 2017.

Other researchers from the University of Washington and from Washington State University Vancouver are coauthors of the paper. Samsung Research America through the Think Tank Team Award funded the work.

Source: University of Washington

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