WEST LAFAYETTE, Ind. – Patented and patent-pending technologies developed by engineers at Purdue University improve methods for detecting, identifying and quantifying chemicals in a range of natural, industrial and consumer contexts.
Joe Sinfield, professor of civil engineering, and researchers in his laboratory at Purdue University’s Lyles School of Civil Engineering, have created a suite of technologies to expand the applications of Raman spectroscopy, a chemical analysis technique that uses light to evaluate chemical composition of materials. The technique has traditionally been performed with expensive and sophisticated devices in controlled environments such as laboratories, or low-cost and much less capable instruments in more challenging environments. When chemical differentiation, sensitivity and / or specificity is required, those in need of chemical analysis typically resort to taking samples of a substance in a laboratory for analysis, which can be expensive and time-consuming.
“This performance trade-off was driven by the inherent challenges of performing chemical detection in natural, industrial and consumer environments,” said Sinfield. “Measurements in the real world are subject to multiple forms of interference and often require the analysis of chemicals present in low concentrations, which can affect the environment and / or human health.”
Leveraging recent advances in laser technologies, fiber optics, and digital signal processing, the Purdue Civil Engineering Spectroscopy Laboratory has opened up the ability to perform chemical analysis on a wide range of highly sensitive compounds outside the laboratory, to moderate cost and with little need for experience or sample preparation.
“We want those working in natural and industrial environments to take advantage of the sophisticated quantification capabilities that are traditionally available in a laboratory, and we are making this possible by addressing four major problems,” said Sinfield.
Overcoming of optical interference from fluorescence
One of Sinfield’s inventions addresses the interference of fluorescence. In Raman spectroscopy, light is focused on a material to make a measurement. A small fraction of that light is scattered from the material providing important information about its composition, which is what makes the Raman technique valuable. However, some other light is often absorbed by the material and re-emitted as a fluorescence.
“This fluorescence emission is spectrally large, very strong and, in many contexts, overwhelms the desired scattering,” said Sinfield. “The emission of the fluorescence, however, takes time – several billionths of a second. The electrons have to absorb the incident energy, move to a higher energy state, and then re-emit the light to relax.
“We use a very fast time-gating process that allows us to observe dispersion from the molecule before significant fluorescence, providing us with information on the composition of materials in traditionally difficult contexts.”
Correction of physical interference from turbidity
Another of Sinfield’s technologies addresses the problems created by objects in samples that don’t typically interest researchers, such as dust or soil particles. These particles can cause liquids or solutions to appear cloudy or cloudy, which can interfere with chemical analyzes.
“When we want a quantitative measurement of a chemical in a material, for example in water, we want to be able to know its concentration, it is the amount of chemical contained in a defined volume,” said Sinfield. “If there are particles we don’t want to measure in the material, they are taking up space which can interfere with our control volume.”
Sinfield’s second patented technology solves the problem.
“It automatically represents the volume occupied by suspended particles in a solution so that Raman measurements are truly representative of what is in the liquid,” said Sinfield. “This can be very important in water quality analyzes, industrial processes or other contexts involving fluids.”
Achieve sensitivity in low concentration environments
“While overcoming obstacles such as fluorescence and turbidity is useful in many situations, some contexts are even more difficult as very small amounts of chemicals may need to be detected,” said Sinfield. “This is especially important when chemicals can be dangerous at very low concentrations. Although sensitive Raman measurements such as these are performed regularly in the laboratory, they are very difficult to perform in less controlled environments.”
Two of Sinfield’s inventions improve the sensitivity of the Raman system to allow for chemical analysis in these challenging situations. One is an extension of what is sometimes called a single photon count. Sinfield’s technology uses digital signal processing algorithms to interpret the output of optical detectors based on the energy of individual photons of light, which allows a system equipped with the algorithms to detect small amounts of chemicals that disperse large quantities. small of light.
“While a typical flashlight could emit about 100 billion trillion photons per second, low-concentration chemicals disperse very few of them in the same amount of time. We can see even a single photon and count it,” Sinfield said.
“In many cases, we can examine compounds of interest that are important for industrial process control or the environment in challenging contexts and get accurate measurements at very low concentrations. In detection scenarios, we don’t have to wait for something to be right either. very high concentration to find out. We can see it soon and tell how much it is. “
Sinfield’s technique also improves the dynamic range of a sensor, which means that a single system can examine both low- and high-concentration compounds, tolerating both weak and strong dispersion responses.
Another Sinfield group sensitivity enhancement patent relates to the detection of chlorinated solvents. These compounds were once used as degreasers in dry cleaning, automotive and military applications and are now known to be harmful to human health at very low concentrations in groundwater. While they are typically very difficult to detect and monitor, Sinfield’s group found that they could see compounds without looking for them specifically.
“It turns out that their presence in water fundamentally changes the water. Just a small concentration changes the Raman signature of the bulk water,” Sinfield said. “So rather than looking for a compound with a very low concentration, we can look for changes in the water signature that tell us that chlorinated solvents are present. This inferential detection capability allows the sensor to infer that the compound is present by observing the solvent. bulk, which is much easier to examine. “
Enabling of spatially dispersed analyzes
Even when sensitivity can be achieved in measurements in one location, it can be important to collect information in multiple locations to assess the chemical distribution in an environment or to monitor the concentration of chemicals at different points in a process. With many traditional methods of analysis, this may require the use of multiple sensors and / or repeated and expensive sampling and subsequent laboratory analysis.
“We have improved our laser-based Raman system with long-distance optical fibers and optical switches similar to those used in the telecommunications industry,” said Sinfield. “We can send light through a multi-position fiber via an all-optical switch and conduct chemical analysis remotely. Depending on the sensitivity required and the chemicals of interest, we can place a sensing node in one location and other sensing node counters. or miles away and take measurements at every point from an instrument. Through the electronic control of the optical switch, we have the potential to assess conditions in different places in seconds or minutes. “
Sinfield revealed these spectroscopy innovations at the Purdue Research Foundation Office of Technology Commercialization.
“Our team is excited to put our technologies into practice, improve existing Raman spectroscopy systems, or develop entirely new tools for previously unaddressed applications,” said Sinfield. “The technologies we have developed are very versatile.”
Industry partners seeking to select or license these innovations should contact Dhananjay Sewak, firstname.lastname@example.org, regarding fluorescence overcoming reference number 64902, 2014-SINF-66635 for turbidity correction, 2021 -SINF-69456 for low concentration settings and 2022- SINF-69571 for spatially dispersed analysis.
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About the Purdue Research Foundation’s Office for Commercialization of Technology
The Purdue Research Foundation Office of Technology Commercialization operates one of the most comprehensive technology transfer programs among leading research universities in the U.S. Services provided by this office support Purdue University’s economic development initiatives and benefit the university’s academic activities through the marketing, licensing and protection of Purdue intellectual property. The office is housed in the Convergence Center for Innovation and Collaboration in the Discovery Park District on Purdue, adjacent to the Purdue campus. In fiscal 2020, the office reported 148 agreements concluded with 225 technologies signed, 408 disclosures received, and 180 U.S. patents issued. The office is managed by the Purdue Research Foundation, which received the Innovation and Economic Prosperity Universities Award 2019 for the post from the Association of Public and Land-grant Universities. In 2020, IPWatchdog Institute ranked Purdue third nationwide for startup creation and in the top 20 for patents. The Purdue Research Foundation is a private non-profit foundation created to further the mission of Purdue University. Contact email@example.com for more information.
Writer: Steve Martin, firstname.lastname@example.org
Source: Joe Sinfield, email@example.com