Wednesday, 22 May 2019

Researchers show tissue paper sensors hold promise for health care, entertainment, robotics

Each piece of tissue paper has both horizontal and vertical fibers, so when the paper is torn, the direction of the tear informs the sensor of what's happened

14 Feb 2018 | Editor

According to a recent research paper University of Washington engineers have turned tissue paper - similar to toilet tissue - into a new kind of wearable sensor that can detect a pulse, a blink of an eye and other human movement. The sensor is light, flexible and inexpensive, with potential applications in health care, entertainment and robotics.

The technology, described in a paper published recently shows that by tearing tissue paper that's loaded with nanocomposites and breaking the paper's fibers, the paper acts as a sensor. It can detect a heartbeat, finger force, finger movement, eyeball movement and more.

These small, Band Aid-sized sensors could have a variety of applications in various fields. 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.

In their research, the scientists used paper similar to toilet tissue. The paper - nothing more than conventional paper towels - is then doused with carbon nanotube-laced water. Carbon nanotubes are tiny materials that create electrical conductivity. Each piece of tissue paper 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 been contained to a laboratory, and researchers are hoping to find a suitable commercial use. A provisional patent was filed in December 2017.

The study was funded partially by Samsung Research America through the Think Tank Team Award.

"The major innovation is a disposable wearable sensor made with cheap tissue paper"

"When we break the specimen, it will work as a sensor."

"They can use these sensors and after one-time use, they can be thrown away."

Jae-Hyun Chung, A UW associate professor of mechanical engineering and senior author of the research

Fracture-Induced Mechanoelectrical Sensitivities of Paper-Based Nanocomposites

Jinyuan Zhang | Gil-Yong Lee | Chiew Cerwyn | Jinkyu Yang | Fabrice Fondjo | Jong-Hoon Kim | Minoru Taya | Dayong Gao | Jae-Hyun Chung

First published: 26 January 2018 | Full publication history | DOI: 10.1002/admt.201700266


Nanostructured composites built with microporous cellulose fibers and carbon nanotubes (CNTs) have potential impacts in the fields of energy storage, sensors, and flexible electronics. Few results have been shown for high mechanoelectrical sensitivity of CNT-paper composite because of numerous current paths in the network. Here, CNT-paper-based nanostructured composite sensors whose sensitivities are generated by controlled tensile fracture of the composite are presented. Under uniaxial load, the cellulose fibers in the paper experience straightening, stiffening, and fracture. The cellulose fibers originally parallel to the tension are fractured while those inclined and perpendicular to the tension are reorganized to form crossbar junctions in the vicinity of a crack. The cross junctions exhibit resistive and capacitive sensitivity to the out-of-plane force by the compression of the junctions. Such piezoresistive and piezocapacitive sensitivities are characterized and evaluated for human behavior monitoring.


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Source: University of Washington

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