Researchers create switchable mirrors from liquid metal
Approach could be used to create electrically controlled mirrors for art or advanced devices
2021-06-14
(Press-News.org) WASHINGTON -- Researchers have developed a way to dynamically switch the surface of liquid
metal between reflective and scattering states. This technology could one day be used to create electrically controllable mirrors or illumination devices.
Liquid metals combine the electrical, thermal and optical properties of metals with the fluidity of a liquid. The new approach uses an electrically driven chemical reaction to create switchable reflective surfaces on a liquid metal. No optical coatings nor polishing steps, which are typically required to make reflective optical components, are necessary to make the liquid metal highly reflective.
In the Optical Society (OSA) journal Optical Materials Express, researchers led by Yuji Oki of Kyushu University in Japan show that switching between reflective and scattering states can be achieved with just 1.4 V, about the same voltage used to light a typical LED. The researchers collaborated with Michael D. Dickey's research team at North Carolina State University to develop the new method, which can be implemented at ambient temperature and pressures.
"In the immediate future this technology could be used to create tools for entertainment and artistic expression that have never been available before," said Oki. "With more development, it might be possible to expand this technology into something that works much like 3D printing for producing electronically controlled optics made of liquid metals. This could allow the optics used in light-based health testing devices to be easily and inexpensively fabricated in areas of the world that lack medical laboratory facilities."
Creating an optical surface
In the new work, the researchers created a reservoir using an embedded flow-channel. They then used a "push-pull method" to form optical surfaces by either pumping gallium-based liquid metal into or sucking it out of the reservoir. This process formed convex, flat, or concave surfaces; each with different optical properties.
Then, by applying electricity, the researchers initiated a chemical reaction that reversibly oxidizes the liquid metal. The oxidation changes the liquid's volume in a way that creates many small scratches on the surface that cause light to scatter. When electricity is applied in the opposite direction, the liquid metal returns to its original state. The liquid metal's surface tension causes the scratches to disappear, restoring the surface to a clean reflective mirror state.
The researchers discovered the new technique serendipitously while experimenting with a liquid metal to see if it could be used to make molds to use with a silicone elastomer. "Our intention was to use oxidation to change the surface tension and reinforce the surface of the liquid metal," said Oki. "However, we found that, under certain conditions, the surface would spontaneously change into a scattering surface. Instead of considering this a failure, we optimized the conditions and verified the phenomenon."
Characterizing the phenomenon
The researchers electrochemically and optically characterized the different surfaces that were created by applying electricity. They found that changing the voltage on the surface from -800 mV to +800 mV would decrease the light intensity as the surface changed from reflective to scattering. The electrochemical measurements revealed that a voltage change of 1.4 V was sufficient to create redox reactions with good reproducibility.
"We also found that under certain conditions the surface can be slightly oxidized and still maintain a smooth reflective surface," said Oki. "By controlling this, it might be possible to create even more diverse optical surfaces using this approach that could lead to applications in advanced devices such as biochemical chips or be used to make 3D printed optical elements."
INFORMATION:
Paper: K. Nakakubo, H. Yoshioka, K. Morita, R. Ishimatsu, A. Kiani, H. Hallen, M. D. Dickey, Y. Oki, "Dynamic control of reflective/diffusive optical surfaces on EGaIn liquid metal," Opt. Mater. Express 11, 7, 2099 - 2108 (2021).
DOI: https://doi.org/10.1364/OME.425432.
Optical Materials Express
Optical Materials Express is an open-access journal focusing on the synthesis, processing and characterization of materials for applications in optics and photonics. It is published by The Optical Society (OSA) and emphasizes advances in novel optical materials, their properties, modeling, synthesis and fabrication techniques; how such materials contribute to novel optical behavior; and how they enable new or improved optical devices. The editor-in-chief is Alexandra Boltasseva from Purdue University, USA. Optical Materials Express is available online at OSA Publishing.
About The Optical Society
Founded in 1916, The Optical Society (OSA) is the leading professional organization for scientists, engineers, students and business leaders who fuel discoveries, shape real-life applications and accelerate achievements in the science of light. Through world-renowned publications, meetings and membership initiatives, OSA provides quality research, inspired interactions and dedicated resources for its extensive global network of optics and photonics experts. For more information, visit osa.org.
Media Contact:
mediarelations@osa.org
[Attachments] See images for this press release:
ELSE PRESS RELEASES FROM THIS DATE:
2021-06-14
COLUMBIA, Mo. -- While the United States faces a nationwide nursing shortage, a recent study at the University of Missouri found rural Missouri counties experience nursing shortages at a greater rate than the state's metropolitan counties. In addition, the study found rural Missouri counties have a higher percentage of older nurses nearing retirement, which could have a severe impact on the future of the state's nursing workforce.
Anne Heyen, an assistant teaching professor in the MU Sinclair School of Nursing, analyzed workforce data of nearly 136,000 licensed Missouri nurses to identify the age and geographical disparities ...
2021-06-14
DARIEN, IL - More veterans are receiving important sleep care, especially those living in rural areas where access to sleep medicine specialists can be difficult. The Veterans Health Administration's TeleSleep Program launched telehealth services in 2017 to support the testing, diagnosis, and treatment of obstructive sleep apnea and other sleep disorders. More than one million veterans who received care from VHA in 2020 have sleep apnea.
"The implementation of these services has been very successful," said Dr. Kathleen Sarmiento, program lead for the Office of Rural Health TeleSleep ...
2021-06-14
Red seaweeds have been prevalent in the diets of Asian communities for thousands of years. In a new study, published in Marine Drugs, researchers have shown how these algae confer health benefits.
"In the past, people have wondered why the number of colon cancer patients in Japan is the lowest in the world," said Yong-Su Jin (CABBI/BSD/MME), a professor of food microbiology. "Many assumed that it was due to some aspect of the Japanese diet or lifestyle. We wanted to ask whether their seaweed diet was connected to the lower frequency of colon cancer."
Although several studies have shown that Asians who eat seaweed regularly have lower risk of colon, ...
2021-06-14
Methane is a strong greenhouse gas that plays a key role in Earth's climate. Anytime we use natural gas, whether we light up our kitchen stove or barbeque, we are using methane.
Only three sources on Earth produce methane naturally: volcanoes, subsurface water-rock interactions, and microbes. Between these three sources, most is generated by microbes, which have deposited hundreds of gigatons of methane into the deep seafloor. At seafloor methane seeps, it percolates upwards toward the open ocean, and microbial communities consume the majority of this methane before it reaches the atmosphere. Over the years, researchers are finding more and more methane beneath the seafloor, yet very little ever leaves the oceans and gets into the atmosphere. Where ...
2021-06-14
HOUSTON - (June 14, 2021) - In the two decades since the Human Genome Project mapped the entire human genome, improvements in technology have helped in developing updated reference genomes used for sequencing. But while the GRCh38 (hg38) human reference genome was released more than seven years ago, the older GRCh37 (hg19) reference remains widely used by most research and clinical laboratories. In a new study published in the American Journal of Human Genetics, researchers at the Human Genome Sequencing Center at Baylor College of Medicine identify ...
2021-06-14
HOUSTON - (June 14, 2021) - Osteogenesis imperfecta (OI) is the most common genetic form of brittle bone disease and results in defects of both bone and connective tissue. OI patients can have significant problems with mobility due to joint dysfunction due in part to tendinopathy. In a new study published in the journal Proceedings of the National Academy of Sciences, researchers at Baylor College of Medicine identify a protein signaling mechanism driving this dysfunction and find that inhibiting this signaling pathway can prevent onset of tendinopathy problems in mouse models.
The ...
2021-06-14
DARIEN, IL - According to a study of data from more than 163,000 Fitbit users, sleep duration increased slightly in 2020 during the COVID-19 pandemic compared with a similar timeframe in 2019.
Results show that mean sleep duration increased in nearly all groups by 5 to 11 minutes, compared with a mean decrease of 5 to 8 minutes seen over the same period in 2019. Sleep timing shifted later for nearly all groups. Sleep duration and bedtime variability decreased, largely due to fewer differences between weekday and weekend sleep.
"The most surprising thing we found was that, overall, sleep duration increased slightly, and sleep variability decreased slightly, during the most ...
2021-06-14
The World Health Organization describes empowerment as a process in which people can take control and make informed decisions about their life and health. Empowerment is important for people with RA since most care is provided by patients themselves.
Andersson and colleagues studied levels of empowerment and associated variables in people with RA, and investigated longitudinal clinical data in those with low and high levels of empowerment. The study involved 2837 people with RA from the BARFOT (Better Anti-Rheumatic PharmacO Therapy) cohort. Everyone was assessed according to a structured protocol at ...
2021-06-14
BALTIMORE (June 14, 2021) - Researchers at the University of Maryland School of Medicine (UMSOM) analyzed data at the 13-hospital University of Maryland Medical System (UMMS) and found public health measures designed to reduce the spread of the COVID-19 virus may have fostered a substantial side benefit: Hospital admissions for chronic obstructive pulmonary disease (COPD) were reduced by 53 percent, according to a new study published in The American Journal of Medicine. This is likely due to a drop in circulating seasonal respiratory viruses such as influenza.
Hospitalizations for COPD, a group of lung diseases that make it hard to breathe and get worse over time, are commonly driven by flare-ups where symptoms are triggered by such factors ...
2021-06-14
In many parts of the world, mosquitoes are a common summertime nuisance.
But in places on the front lines of climate change, these disease-spreading insects may one day be a year-round problem, according to new research from the University of Florida.
"In tropical regions, mosquitoes are active all year, but that isn't the case for the rest of the world. Outside of the tropics, winter temperatures cause mosquitoes to go into a kind of hibernation called diapause. We call these mosquitoes 'cold bounded' because their activity is limited by these lower temperatures," said Brett Scheffers, senior author of the study and an assistant professor in the UF/IFAS wildlife ecology and conservation department.
"However, ...
LAST 30 PRESS RELEASES:
[Press-News.org] Researchers create switchable mirrors from liquid metal
Approach could be used to create electrically controlled mirrors for art or advanced devices
