Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Sweating the small stuff

02.05.2018

A membrane with nanoscale pores allows controlled sweat stimulant release, paving the way to measure small samples of sweat in wearable biosensing devices

When people sweat, they unknowingly release a wide range of chemicals that can noninvasively inform clinicians on anything from stress hormone levels to glucose. But it's hard for researchers to glean this information -- unless you sweat a lot. Emerging wearable devices using stimulant gels have provided a way to induce sweat locally on the body. However, sweat can dilute these gels, which degrades their long-term viability.


In vivo testing of membrane technology using iontophoresis.

Credit: Phillip Simmers, Zachary Sonner and Jason Heikenfeld

An international team of researchers recently developed a new membrane that mitigates both issues that arise from direct dermal contact and sweat dilution for sweat biosensors. As discussed in Biomicrofluidics, by AIP Publishing, the membrane performs hundreds of times better than other methods and holds up to repeated use.

"Everyday use of sweat biosensing is on the horizon, but first we need to work out a few problems, including how to obtain useful samples when patients aren't exerting themselves," said Phillip Simmers, an author on the paper. "Controlled dosing is very important to the medical community."

Iontophoretic devices -- which would draw on the team's membrane -- work by applying a small voltage across the skin to guide a charged drug through the epidermis. Most sweat stimulation devices use a stimulant that is dissolved into a hydrogel at high concentrations to make sure the dosing can be maintained.

While stimulants such as carbachol are useful because the body slowly metabolizes them, they cannot specifically target sweat glands and pose potential risk if an additional stimulant enters the body. When the stimulant activates sweat production, the resulting mélange of hydrogel and sweat not only makes it difficult for the stimulant to reach the skin, but also for the biosensor to accurately read the sweat.

"One of the biggest challenges was that when we sweat, we're actively losing analytes to the gel, which is an issue that hasn't been addressed," Simmers said.

Simmers and his team first constructed an in vitro model to determine which commercially available filtration membranes were best suited for limiting the passive diffusion of carbachol. They found that the best membranes had nanoscale pores and retained more than 90 percent of their initial stimulant concentration after 24 hours, while allowing only a minimal amount of sweat to pass through.

The group then ported this technology to dime-sized adhesive patches and tested them on patients. Using bromophenol blue dye and silicone oil that changes color in the presence of sweat, they were able to confirm that the nanoscale pores identified earlier during their in vitro experiments could still deliver controlled dosing that induced the human sweat response, proving that the membrane was effectively isolating the sweat from the stimulant.

Next up, the group hopes to incorporate their findings into a wearable biosensing prototype that they have already developed. Simmers said he hopes the paper's findings will also stoke interest in how to better produce membrane materials for such devices.

###

The article, "Membrane isolation of repeated-use sweat stimulants for mitigating both direct dermal contact and sweat dilution," is authored by P. Simmers, Y. Yuan, Z. Sonner and J. Heikenfeld. The article will appear in Biomicrofluidics May 1, 2018 (DOI: 10.1063/1.5023396). After that date, it can be accessed at http://aip.scitation.org/doi/full/10.1063/1.5023396.

ABOUT THE JOURNAL

Biomicrofluidics publishes research highlighting fundamental physiochemical mechanisms associated with microfluidic and nanofluidic phenomena as well as novel microfluidic and nanofluidic techniques for diagnostic, medical, biological, pharmaceutical, environmental, and chemical applications. See http://bmf.aip.org.

Media Contact

Julia Majors
media@aip.org
301-209-3090

 @AIPPhysicsNews

http://www.aip.org 

Julia Majors | EurekAlert!

More articles from Physics and Astronomy:

nachricht Neutrino-Observatorium IceCube am Südpol wird ausgebaut
17.07.2019 | Deutsches Elektronen-Synchrotron DESY

nachricht Flying Laptop satellite mission extended by two years - Successfully in orbit since July 14, 2017
16.07.2019 | Universität Stuttgart

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Megakaryocytes act as „bouncers“ restraining cell migration in the bone marrow

Scientists at the University Würzburg and University Hospital of Würzburg found that megakaryocytes act as “bouncers” and thus modulate bone marrow niche properties and cell migration dynamics. The study was published in July in the Journal “Haematologica”.

Hematopoiesis is the process of forming blood cells, which occurs predominantly in the bone marrow. The bone marrow produces all types of blood cells: red...

Im Focus: Artificial neural network resolves puzzles from condensed matter physics: Which is the perfect quantum theory?

For some phenomena in quantum many-body physics several competing theories exist. But which of them describes a quantum phenomenon best? A team of researchers from the Technical University of Munich (TUM) and Harvard University in the United States has now successfully deployed artificial neural networks for image analysis of quantum systems.

Is that a dog or a cat? Such a classification is a prime example of machine learning: artificial neural networks can be trained to analyze images by looking...

Im Focus: Extremely hard yet metallically conductive: Bayreuth researchers develop novel material with high-tech prospects

An international research group led by scientists from the University of Bayreuth has produced a previously unknown material: Rhenium nitride pernitride. Thanks to combining properties that were previously considered incompatible, it looks set to become highly attractive for technological applications. Indeed, it is a super-hard metallic conductor that can withstand extremely high pressures like a diamond. A process now developed in Bayreuth opens up the possibility of producing rhenium nitride pernitride and other technologically interesting materials in sufficiently large quantity for their properties characterisation. The new findings are presented in "Nature Communications".

The possibility of finding a compound that was metallically conductive, super-hard, and ultra-incompressible was long considered unlikely in science. It was...

Im Focus: Modelling leads to the optimum size for platinum fuel cell catalysts: Activity of fuel cell catalysts doubled

An interdisciplinary research team at the Technical University of Munich (TUM) has built platinum nanoparticles for catalysis in fuel cells: The new size-optimized catalysts are twice as good as the best process commercially available today.

Fuel cells may well replace batteries as the power source for electric cars. They consume hydrogen, a gas which could be produced for example using surplus...

Im Focus: The secret of mushroom colors

Mushrooms: Darker fruiting bodies in cold climates

The fly agaric with its red hat is perhaps the most evocative of the diverse and variously colored mushroom species. Hitherto, the purpose of these colors was...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on UV LED Technologies & Applications – ICULTA 2020 | Call for Abstracts

24.06.2019 | Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

 
Latest News

Neutrino-Observatorium IceCube am Südpol wird ausgebaut

17.07.2019 | Physics and Astronomy

Atacama Desert: Some lichens can meet their need for water from air humidity

17.07.2019 | Life Sciences

New DFG Research Group "Metrology for THz Communications"

17.07.2019 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>