Nav: Home

Pin-sized sensor could bring chemical ID to smartphone-sized devices

April 09, 2019

MADISON, Wis. -- Imagine pointing your smartphone at a salty snack you found at the back of your pantry and immediately knowing if its ingredients had turned rancid.

Devices called spectrometers can detect dangerous chemicals based on a unique "fingerprint" of absorbed and emitted light. But these light-splitting instruments have long been both bulky and expensive, preventing their use outside the lab.

Until now. Engineers at the University of Wisconsin-Madison have developed a spectrometer so small and simple that it could integrate with the camera of a typical cellphone without sacrificing accuracy.

"This is a compact, single-shot spectrometer that offers high resolution with low fabrication costs," says Zhu Wang, who was among the team of electrical engineers that created the device.

The researchers published a description of the devices recently in the journal Nature Communications.

The team's devices also have an advanced capability called hyperspectral imaging, which collects information about each individual pixel in an image order to identify materials or detect specific objects amidst a complicated background.

Hyperspectral sensing, for example, could be used to detect seams of valuable minerals within rock faces or to identify specific plants in a highly vegetated area.

Every element's spectral fingerprint includes unique emitted or absorbed wavelengths of light -- and the spectrometer's ability to sense that light is what has enabled researchers to do everything from analyze the composition of unknown compounds to reveal the makeup of distant stars.

Spectrometers usually rely on prisms or gratings to split light emitted from an object into discrete bands -- each corresponding to a different wavelength. A camera's photodetector can capture and analyze those bands. The spectral fingerprint of the element sodium, for example, consists of two bands with wavelengths of 589 and 590 nanometers.

Human eyes see 590-nanometer wavelength light as a yellowish-orange shade. Shorter wavelengths correspond to blues and purples, whereas longer wavelengths appear red. Sunlight contains a complete rainbow mixed together, which we see as white.

To resolve the difference among a mixture of different colors, spectrometers usually must be relatively large with a long path length for light beams to travel and separate. Yet the team created tiny spectrometers, measuring just 200 micrometers on each side (roughly one-20th the area of a ballpoint pen tip) and delicate enough to lie directly on a sensor from a typical digital camera.

That small size was possible because the researchers based their device on specially designed materials that forced incoming light to bounce back and forth several times before reaching the sensor. Those internal reflections elongated the path along which light traveled without adding bulk, boosting the devices' resolution.

And the devices performed hyperspectral imaging, resolving two distinct images (of the numbers 5 and 9) from a snapshot of an overlaid projection that combined the pair into something indistinguishable to the naked eye.

Now the team hopes to boost the device's spectral resolution as well as the clarity and crispness of the images it captures. Those improvements could pave the way for even more enhanced sensors.
-end-
Yu's collaborators at UW-Madison included engineering Professor Mikhail Kats, Soongyu Yi, Ang Chen, Ming Zhou, Graham Joe and Alireza Shahsafi. Ken Xingze Wang of Huazhong University of Science and Technology and Ting Shan Luk, Anthony James, John Nogan and Willard Ross of Sandia National Laboratories contributed to the research.

This research was supported by the National Science Foundation and the Defense Advanced Research Projects Agency CAREER Award and DARPA Young Faculty Award (YFA) supported the research.

DOWNLOAD IMAGES: https://uwmadison.box.com/v/tiny-spectrometer

--Sam Million-Weaver, perspective@engr.wisc.edu

University of Wisconsin-Madison

Related Fingerprint Articles:

Atomic fingerprint identifies emission sources of uranium
Depending on whether uranium is released by the civil nuclear industry or as fallout from nuclear weapon tests, the ratio of the two anthropogenic, i.e. man-made, uranium isotopes 233U and 236U varies.
Prostate cancer 'fingerprint' detected in blood sample
Scientists at UCL have invented a new test to identify the earliest genetic changes of prostate cancer in blood: a process which could allow doctors to see if cancers have spread, monitor tumor behavior and enable better treatment selection.
Experimental fingerprint test can distinguish between those who have taken or handled cocaine
An experimental fingerprint detection approach can identify traces of cocaine on human skin, even after someone has washed their hands -- and the test is also smart enough to tell whether an individual has actually consumed the class A drug, or simply handled it.
OU study finds the fingerprint of paddy rice in atmospheric methane concentration dynamics
A University of Oklahoma-led study shows that paddy rice (both area and plant growth) is significantly related to the spatial-temporal dynamics of atmospheric methane concentration in monsoon Asia, where 87% of paddy rice fields are situated in the world.
Fingerprint test can distinguish between those who have taken or handled heroin
A state-of-the-art fingerprint detection technology can identify traces of heroin on human skin, even after someone has washed their hands -- and it is also smart enough to tell whether an individual has used the drug or shaken hands with someone who has handled it.
A precise chemical fingerprint of the Amazon
This novel drone-based chemical monitoring system tracks the health of the Amazon in the face of global climate change and human-caused deforestation and burning.
Canadian astronomers determine Earth's fingerprint
Two McGill University astronomers have assembled a 'fingerprint' for Earth, which could be used to identify a planet beyond our Solar System capable of supporting life.
Fingerprint of sleep habits as warning sign for heart disease
Chronic short sleep is associated with increased risk of clogged arteries, heart disease, and thus increased morbidity and mortality.
Scientists see fingerprint of warming climate on droughts going back to 1900
In an unusual new study, scientists say they have detected the fingerprint of human-driven global warming on patterns of drought and moisture across the world as far back as 1900.
'Fingerprint database' could help scientists to identify new cancer culprits
Scientists in Cambridge and London have developed a catalogue of DNA mutation 'fingerprints' that could help doctors pinpoint the environmental culprit responsible for a patient's tumour - including showing some of the fingerprints left in lung tumours by specific chemicals found in tobacco smoke.
More Fingerprint News and Fingerprint 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

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
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

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at Radiolab.org/donate.