Nav: Home

Good vibrations: Using piezoelectricity to ensure hydrogen sensor sensitivity

May 22, 2019

Osaka, Japan - A team at Osaka University has invented a new process for creating high-precision sensing devices that respond to the presence of hydrogen gas. By carefully controlling the deposition of metallic nanoparticles on a silicon surface, the researchers were able to create a sensor that can detect low levels of hydrogen on the basis of changes in electrical current. This research may have important benefits as part of a switch to hydrogen-based fuels, which could power the zero-emission cars of the future and help fight anthropogenic climate change.

To fabricate a hydrogen sensor, the researchers deposited metallic palladium on a silicon substrate. The deposited palladium forms nanoparticles on the substrate, and they act like tiny islands that are excellent conductors of electricity, but, because they do not form a connected network, the current across the device is very small.

However, when hydrogen atoms are present, they are absorbed into the palladium nanoparticles, increasing volume of the nanoparticles, and then bridge the gaps between the islands. Eventually, a completely connected path is formed, and electrons can flow with much less resistance. In this way, even a tiny change in hydrogen concentration can lead to a massive increase in current, so the devices can be made very sensitive.

A significant challenge the Osaka researchers had to overcome was precisely controlling the gaps between islands to deposit in the first place. If the deposition time was too short, gaps between the nanoparticles are too wide and they would not be bridged even when hydrogen was present. Conversely, if the deposition time was too long, the nanoparticles would form a connected network on their own, even before hydrogen was applied. To optimize the response of the sensor, the research team developed a novel method for monitoring and controlling the deposition of palladium called piezoelectric resonance.

"Piezoelectric materials, such as a quartz crystal in a wristwatch, can vibrate at a very specific frequency in response to an applied voltage," senior author Dr. Hirotsugu Ogi explains. Here, a piece of piezoelectric lithium niobate was set to vibrate underneath the sample during the metallic nanoparticle deposition. The oscillating piezoelectric created an electric field around the sample, which in turn induced a current in the device that depended on the connectivity of the palladium network.

Then, the attenuation of the oscillation changes depending on the connectivity. Therefore, by listening to the sound (measuring the attenuation) of the piezoelectric material, the connectivity can be monitored.

"By optimizing the deposition time using the piezoelectric resonance method, the resulting hydrogen sensors were 12 times more sensitive than before," first author Dr. Nobutomo Nakamura says. "These devices may represent a step towards a cleaner energy future involving hydrogen."

The work is published in Applied Physics Letters as "Precise control of hydrogen response of semicontinuous palladium ?lm using piezoelectric resonance method." (DOI:10.1063/1.5094917)
-end-
About Osaka University

Osaka University was founded in 1931 as one of the seven imperial universities of Japan and now has expanded to one of Japan's leading comprehensive universities. The University has now embarked on open research revolution from a position as Japan's most innovative university and among the most innovative institutions in the world according to Reuters 2015 Top 100 Innovative Universities and the Nature Index Innovation 2017. The university's ability to innovate from the stage of fundamental research through the creation of useful technology with economic impact stems from its broad disciplinary spectrum.

Website: https://resou.osaka-u.ac.jp/en/top

Osaka University

Related Nanoparticles Articles:

Nanoparticles: Acidic alert
Researchers of Ludwig-Maximilians-Universitaet (LMU) in Munich have synthesized nanoparticles that can be induced by a change in pH to release a deadly dose of ionized iron within cells.
3D reconstructions of individual nanoparticles
Want to find out how to design and build materials atom by atom?
Directing nanoparticles straight to tumors
Modern anticancer therapies aim to attack tumor cells while sparing healthy tissue.
Sweet nanoparticles trick kidney
Researchers engineer tiny particles with sugar molecules to prevent side effect in cancer therapy.
A megalibrary of nanoparticles
Using straightforward chemistry and a mix-and-match, modular strategy, researchers have developed a simple approach that could produce over 65,000 different types of complex nanoparticles.
Dialing up the heat on nanoparticles
Rapid progress in the field of metallic nanotechnology is sparking a science revolution that is likely to impact all areas of society, according to professor of physics Ventsislav Valev and his team at the University of Bath in the UK.
Illuminating the world of nanoparticles
Scientists at the Okinawa Institute of Science and Technology Graduate University (OIST) have developed a light-based device that can act as a biosensor, detecting biological substances in materials; for example, harmful pathogens in food samples.
What happens to gold nanoparticles in cells?
Gold nanoparticles, which are supposed to be stable in biological environments, can be degraded inside cells.
Lighting up cardiovascular problems using nanoparticles
A new nanoparticle innovation that detects unstable calcifications that can trigger heart attacks and strokes may allow doctors to pinpoint when plaque on the walls of blood vessels becomes dangerous.
Cutting nanoparticles down to size -- new study
A new technique in chemistry could pave the way for producing uniform nanoparticles for use in drug delivery systems.
More Nanoparticles News and Nanoparticles Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Climate Mindset
In the past few months, human beings have come together to fight a global threat. This hour, TED speakers explore how our response can be the catalyst to fight another global crisis: climate change. Guests include political strategist Tom Rivett-Carnac, diplomat Christiana Figueres, climate justice activist Xiye Bastida, and writer, illustrator, and artist Oliver Jeffers.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Speedy Beet
There are few musical moments more well-worn than the first four notes of Beethoven's Fifth Symphony. But in this short, we find out that Beethoven might have made a last-ditch effort to keep his music from ever feeling familiar, to keep pushing his listeners to a kind of psychological limit. Big thanks to our Brooklyn Philharmonic musicians: Deborah Buck and Suzy Perelman on violin, Arash Amini on cello, and Ah Ling Neu on viola. And check out The First Four Notes, Matthew Guerrieri's book on Beethoven's Fifth. Support Radiolab today at Radiolab.org/donate.