Wearable Sensors Give Skin Space to Breathe

Gold nanomesh sensors last for a week on the skin without causing inflammation

2 min read
Index Finger with Gold Nanomesh Conductor
Photo: 2017 Someya Laboratory/University of Tokyo

Wearable electronics are undergoing a renaissance, from big and bulky to sleek and ultra-thin. Traditional rigid electronics aren’t naturally compatible with soft human skin, and researchers and companies have been developing a suite of stretchable electronics that bend with skin.

At the University of Tokyo, the Someya Group has been on the forefront of the wearables’ makeover. In 2013, they unveiled a tissue-thin, ultra-flexible sheet of electronics. Last year alone, they demonstrated flexible pressure sensors that stay accurate when bent, and organic LED displays that stick to the skin.

This week, in their latest coup, the team describes the successful fabrication of highly breathable on-skin electronics. Described in the journal Nature Nanotechnology, the thin-film electronic devices can be directly laminated onto human skin for a week at a time without causing any skin irritation or discomfort.

“Skin has to breathe or otherwise it will cause inflammation, so we started working on how to introduce breathability” to these devices, says study leader Takao Someya at the University of Tokyo.

Most stretchable electronics made for the skin are only expected to be worn for one day—put on the skin from shower-to-shower—but Someya wanted to prove that a wearable device could be used longer and still be safe and comfortable. To do so, the material needed to be permeable to gases, otherwise it would prevent sweating and block airflow to the skin.

A diagram of the PVA nanofibers The nanomesh, constructed from polyvinyl alcohol (PVA) nanofibers and a gold layer, adheres to the skin when sprayed with water, dissolving the PVA. Illustration: 2017 Someya Laboratory//University of Tokyo

The team’s solution was to create a nanomesh made of widely used polyvinyl alcohol (PVA) fibers spun into an ultra-thin sheet of just 300-500 nanometers. Next, they evaporated a thin (70-100 nm) layer of gold nanoparticles onto the PVA sheet to act as the conductive material. The resulting gold nanomesh adhered to human skin when sprayed with water, which dissolved some of the PVA. The patch easily comes off with washing, says Someya.

In collaboration with dermatologists, the team showed that the on-skin patch did not cause any skin irritation or inflammation on 20 subjects when worn for one week. The patch contained sensors that accurately measured temperature, pressure, and the electrical activity of muscles. They also put it through a mechanical durability gauntlet—bending and stretching a conductor attached to a forefinger more than 10,000 times. The device held up.

Someya plans to continue to improve the durability of the material, as well as add additional functions, such as detecting pulse, blood pressure, and heart rate. Although gold was used to create this device, Someya tells IEEE Spectrum that he hopes to use less expensive materials in the future to reduce manufacturing costs and create inexpensive, disposable sensors.

This latest advance raises the prospect of using such wearable electronics for long-term monitoring of the vital signs of patients or athletes without any discomfort, says Someya. “The continuous monitoring of vital signs may offer a good chance to detect tiny changes that are symptoms of some serious disease in a very early stage,” he adds. “That would be the most exciting part of this development, but this is still an early story.”

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This CAD Program Can Design New Organisms

Genetic engineers have a powerful new tool to write and edit DNA code

11 min read
A photo showing machinery in a lab

Foundries such as the Edinburgh Genome Foundry assemble fragments of synthetic DNA and send them to labs for testing in cells.

Edinburgh Genome Foundry, University of Edinburgh

In the next decade, medical science may finally advance cures for some of the most complex diseases that plague humanity. Many diseases are caused by mutations in the human genome, which can either be inherited from our parents (such as in cystic fibrosis), or acquired during life, such as most types of cancer. For some of these conditions, medical researchers have identified the exact mutations that lead to disease; but in many more, they're still seeking answers. And without understanding the cause of a problem, it's pretty tough to find a cure.

We believe that a key enabling technology in this quest is a computer-aided design (CAD) program for genome editing, which our organization is launching this week at the Genome Project-write (GP-write) conference.

With this CAD program, medical researchers will be able to quickly design hundreds of different genomes with any combination of mutations and send the genetic code to a company that manufactures strings of DNA. Those fragments of synthesized DNA can then be sent to a foundry for assembly, and finally to a lab where the designed genomes can be tested in cells. Based on how the cells grow, researchers can use the CAD program to iterate with a new batch of redesigned genomes, sharing data for collaborative efforts. Enabling fast redesign of thousands of variants can only be achieved through automation; at that scale, researchers just might identify the combinations of mutations that are causing genetic diseases. This is the first critical R&D step toward finding cures.

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