improving wearable medical sensors with ultrathin mesh
This photograph shows the structure of the ultrathin mesh-type polymer PTC thermistors used in wearable medical devices. There are many potential benefits to using mesh in this type of device. Credit: Chihiro Okutani, Shinshu University

On-skin medical sensors and wearable health devices are important health care tools that must be incredibly flexible and ultrathin so they can move with the human body. In addition, the technology has to withstand bending and stretching, and it needs to be gas-permeable to prevent irritation and discomfort. Another important safety feature of these devices is the required overheat protection circuit. This prevents the devices from overheating and burning the wearer. Any new technology developed for these sensors must meet these needs.

In a recent paper, researchers demonstrated how an important component of the sensors called a thermistor can be constructed using an ultrathin fiber-mesh. Thermistors are a type of resistor whose resistance significantly varies with temperature.

The paper was published online in Advanced Scienceon September 4.

“An overheat protection circuit is required to avoid burning biological tissues during the operation of flexible devices. One candidate is a polymer positive temperature coefficient (PTC) thermistor, which has a large increase in resistance within a narrow temperature range,” said Chihiro Okutani, an assistant professor in the Department of Electrical and Computer Engineering at Shinshu University in Japan.

“For such thermistors to be applied for on-skin medical sensors, they must be stretchable and bendable down to several hundred micrometers. However, it is still challenging to fabricate a thermistor whose temperature characteristics do not deteriorate when wrapped around a needle with a bending radius of less than 1 mm.”

improving wearable medical sensors with ultrathin mesh
A photograph of all-mesh thermistor. Credit: Chihiro Okutani, Shinshu University

It is important for this technology to be able to wrap around a needle because sometimes sensors are attached to needles or catheters while in use. In order to achieve this, the thermistor needs to be ultrathin. Researchers used a technique called electrospinning to create the ultrathin mesh-type polymer PTC thermistor. Electrospinning uses electricity to create tiny fibers. The fibers can be made out of different materials, but in this case, researchers used a solution of composite materials.

The newly designed thermistor was then tested to ensure it achieved similar performance capabilities of existing technology. Like typical film-type thermistors, the mesh-type polymer PTC thermistor showed an increase in resistance of three orders of magnitude, an important characteristic for preventing overheating and burns.

By using a mesh structure, the thermistor also achieved transparency, which can help the sensors blend into the skin, and gas-permeability. Gas-permeability is necessary because it prevents irritation and discomfort. “We also demonstrated the operation of the thermistor wrapped around a 280-micrometer needle by fabricating the fibers on a 1.4 micrometer ultrathin film,” said Okutani.

improving wearable medical sensors with ultrathin mesh
Three dimensional measurement of the all-mesh thermistor. Credit: Chihiro Okutani, Shinshu University
improving wearable medical sensors with ultrathin mesh
Magnified Confocal microscope image of the all-mesh thermistor. Credit: Chihiro Okutani, Shinshu University
improving wearable medical sensors with ultrathin mesh
A photograph of the mesh thermistor wrapped around a needle. Credit: Modified from Advanced Science (2022). DOI: 10.1002/advs.202202312

Even with this fiber layer, which serves to give the mesh structure and additional heat sensing, the thermistor remained very thin. This is important because any wearable medical device must be able to withstand bending and when the device is thinner, there is less strain.

Though this thermistor technology is promising, more research will need to be done to make this a reliable alternative to the current thermistor technology on the market. A mesh-type thermistor has a high initial resistance value due to its limited number of conductive paths. The researchers proposed that reducing the spacing between fibers in the mesh or increasing the number of electrodes used could resolve some of these problems, but additional testing will need to be done.

“Our next step is practical applications of the developed thermistors. We believe that the ultraflexible and gas-permeable thermistors can act as overheat prevention components for on-skin or implantable devices, which make flexible sensors safer to operate and more reliable,” said Okutani. More information: Chihiro Okutani et al, Ultrathin Fiber‐Mesh Polymer Thermistors, Advanced Science (2022). DOI: 10.1002/advs.202202312 Journal information: Advanced Science

Provided by Shinshu University Citation: Improving wearable medical sensors with ultrathin mesh (2022, September 29) retrieved 29 September 2022 from https://techxplore.com/news/2022-09-wearable-medical-sensors-ultrathin-mesh.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

TECH NEWS RELATED

City sprawl responsible for acceleration of deep landslide movement, finds study

Houses in Bukavu. Credit: Kimmyfari/Wikimedia Commons, CC BY-SA An international team of researchers has found that an acceleration in movement of a deep landslide beneath the city of Bukavu, in the Democratic Republic of the Congo, is due to city sprawl, not natural forces. In their study, published in ...

View more: City sprawl responsible for acceleration of deep landslide movement, finds study

New biomarkers for coffee consumption

Graphical abstract. Credit: Food Chemistry (2022). DOI: 10.1016/j.foodchem.2022.135026 In search of new biomarkers for nutrition and health studies, a research team from the Leibniz Institute for Food Systems Biology at the Technical University of Munich (LSB) has identified and structurally characterized three metabolites that could be considered as specific ...

View more: New biomarkers for coffee consumption

Apple expands Self Service Repair in Europe, here’s what you need to know

Almost nine months after launching its Self Service Repair program in the US, Apple is now making it available in some European countries. With that, customers in Belgium, France, Germany, Italy, Poland, Spain, Sweden, and the UK can purchase genuine Apple parts and tools. As of now, the Self Service ...

View more: Apple expands Self Service Repair in Europe, here’s what you need to know

Pixel 7 Pro vs. Galaxy S22 Ultra Cameras Tested: Which Zoom is Best?

Both Google's and Samsung's top smartphones have amazing zooms. But which is best?

View more: Pixel 7 Pro vs. Galaxy S22 Ultra Cameras Tested: Which Zoom is Best?

Make Beautiful Family Movies With Your Phone This Holiday Season

Want to capture precious family moments on your phone? These pro tips will help.

View more: Make Beautiful Family Movies With Your Phone This Holiday Season

TikTok Deal Faces More Delays Due to US Security Concerns

Government officials have been slow to reach an agreement with the social media company.

View more: TikTok Deal Faces More Delays Due to US Security Concerns

19 Gizmos and Gadgets at Amazon You Didn’t Know You Needed in Your Life

Whether you're looking for a trinket or two to flesh out your holiday shopping or you're buying for yourself, you won't regret grabbing these knickknacks.

View more: 19 Gizmos and Gadgets at Amazon You Didn’t Know You Needed in Your Life

Archaeologists Claim Homo Naledi Used Fire to Cook, Navigate Dark Caves

This site may earn affiliate commissions from the links on this page. Terms of use. (Photo: Wil Stewart/Unsplash)A group of scientists who recently completed an expedition through South Africa’s Rising Star cave system has made a bold announcement: Homo naledi, an early human species with a brain one-third the size ...

View more: Archaeologists Claim Homo Naledi Used Fire to Cook, Navigate Dark Caves

London based tech firm launch ‘game changing’ festival technology

Bosch to Launch a VR Platform Designed to Offer Social Inclusion

Zscaler Study Finds 90% of Global Enterprises are Adopting Zero Trust, Yet Have Not Unlocked the Full Business Potential

Cybersecurity: What’s in store for 2023?

OkularID joins the Open Identity Exchange

Tiger launches Zoom Phone integration with advanced UC analytics and historic data retention features

French environmentalists file complaint against Apple for being ‘wasteful’

Quality, not just quantity, matters in '30 by 30' goal

6 Best Insta360 X3 Accessories to Create Amazing Videos

Jack Ma gives up title at Zhejiang guild as Alibaba founder keeps up his post-retirement study of fisheries and agriculture

Meta’s Avatar Officially Arrives on WhatsApp

6 Tech Inventions from Classic Movies That We Already Have Now

OTHER TECH NEWS

Top Car News Car News