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Suite of Novel Electronic Systems Developed
May 2016

Woon-Hong Yeo, Ph.D. an assistant professor of mechanical and nuclear engineering, has developed a suite of novel electronic systems that can be mounted on the skin and/ or inserted in the oral cavity. Working with him is a small army of collaborators that include all the departments within the School of Engineering, faculty from the Virginia Commonwealth University (VCU) Schools of Dentistry and Medicine, as well as various outside institutions. Additionally, this research team has collected nearly $1 million in external grants and internal supports to continuously develop skin-like electronic systems.

Nanotattoos, skin-like electronic systems, show potential advancements for smart home health care. Image courtesy of Virginia Commonwealth University.

Before making these strides, Yeo had only a simple insight and simple inspiration. “The majority of health monitoring devices are obtrusive and bulky,” said Yeo. “Think about the existing ECG monitors. They’re made from hard and rigid metals and plastics, but our skin is curvy and soft.” Thus, these devices require conductive gels and taping to fix the gaps and affix to the skin. Critical information, however, can become compromised when the gels degrade and evaporate over time. Plus, the taping causes discomfort and skin irritation.

For Yeo, the path toward the next generation of smart health and monitoring devices began with a wood stick. In its natural form, a large stick is rigid. But, if a stick gets shaved down enough, it becomes a flexible paper that maintains durability. “So I wanted to pick another material to transform in the same way as wood. I chose silicon and other metals to construct electronics,” explained Yeo.

From there, Yeo fashioned nanoscopic structures that were flexible, stretchable and designed open-mesh, meandering shaped electronics to follow the mechanical and material characteristics of the skin. He calls them nanotattoos, because the nanomaterial-based system can be worn on the skin without extra tape or adhesives — just like a temporary tattoo. And, as you’re about to read, they have a lot of different applications.

In partnership with MEDARVA Research Foundation and Richard Constanzo, Ph.D. and director of research in the Department of Otolaryngology — Head and Neck Surgery, Yeo has developed an intraoral nanotattoo with sensors that monitor salt or sugar intake. People following strict dietary guidelines and others with a decline or complete loss in their sense of taste can use the device to evaluate their eating habits. In nursing homes and other care facilities, health care professionals can receive notifications when patients exceed dictated doctor-recommended thresholds for their favorite salty or sweet snacks.

Muscle movements transmit commands that can control prosthetics, robots and even quadcopters. For example, embedded sensors within the nanotattoo on the skin (forearms) interpret muscle movements such as the rotation of wrists, squeezing, and motions to the left and right as different commands to control a helicopter, purely based on human activities.

The nanotattoo records brain signals on the mastoid and auricle, which allows wearers to interact with computers using their thoughts for a text speller, instead of keyboards. For example, if a person looks at a display of letters on a computer screen, the computer can identify which characters the wearer is thinking of and will spell out what the wearers want to communicate. This application has great potential for people with speech or language impairments.

Instead of using plastics or silicone rubbers, this ECG monitoring sensor uses a fabric, and is ideal for long-term monitoring needs on the chest. The small sensor can be mounted to the body and is stretchable, reusable and washable.

Health professionals rely on subjective cues to evaluate cutaneous wound healing. During the healing process, they look to see whether skin color has become red or if excess fluid or swelling is present. Here, this nanotattoo application offers a quantitative, continuous measurement of the skin temperature and hydration of wound tissues.

This article reprinted from materials provided by Virginia Commonwealth University.

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