However, it isn’t that simple for researchers who need to measure temperatures in microfluidic systems—tiny, channel-lined devices used in medical diagnostics, DNA forensics and “lab-on-a-chip” chemical analyzers—as their current “thermometer” can only be precisely calibrated for one reference temperature.
Now, researchers at the National Institute of Standards and Technology (NIST) have proposed a mathematical solution that enables researchers to calibrate the “thermometer” for microfluidic systems so that all temperatures are covered.
Reactions taking place in microfluidic systems often require heating, meaning that users must accurately monitor temperature changes in fluid volumes ranging from a few microliters (a droplet approximately 1 millimeter in diameter) to sub-nanoliters (a droplet approximately 1/10 of millimeter in diameter). A common DNA analysis technique, for example, depends heavily on precise temperature cycling.
Ordinary thermometers or other temperature probes are useless at such tiny dimensions, so some groups have turned to temperature-sensitive fluorescent dyes, particularly rhodamine B. The intensity of the dye’s fluorescence decreases with increasing temperature. The idea is that the dye can be used as a noninvasive way to map the range of temperatures occurring within a microfluidic system during heating and, in turn, provide a means of calibrating that system for experiments.
However, the technique currently requires the user to base all readings on the fluorescence at a single reference temperature. Previous groups have developed “calibration curves” that relate temperature to rhodmaine B fluorescent intensity based on a reference temperature of about 23 degrees Celsius (a technique first proposed by NIST researchers David Ross, Michael Gaitan and Laurie Locascio in 2001*). But it turns out that the curves are only good for that one temperature. In an upcoming paper in Analytical Chemistry**, the NIST team—Jayna J. Shah, Michael Gaitan and Jon Geist—reports that changing the reference point, such as the higher temperature when a microfluidic system is first heated, introduces errors when a dye intensity-to-temperature calculation is done using current methods.
“Our analysis shows that a simple linear correction for a 40 degrees Celsius reference temperature identified errors between minus 3 to 8 degrees Celsius for three previously published sets of calibration equations derived at approximately 23 degrees Celsius,” says lead researcher Shah.
To address the problem, the NIST team developed mathematical methods to correct for the shift experienced when the reference temperature changes. This allowed the researchers to create generalized calibration equations that can be applied to any reference temperature.
Microfluidic DNA amplification (production of numerous copies of DNA from a tiny sample) by the polymerase chain reaction (PCR) is one procedure that could benefit from the new NIST calculations, Shah says. “PCR requires a microfluidic device to be cycled through temperatures at three different zones starting around 65 degrees Celsius, so a useful dye intensity-to-temperature ratio would have to be based on that temperature and not a reference point of 23 degrees Celsius,” she explains.
* D. Ross, M. Gaitan and L.E. Locascio. Temperature measurement in microfluidic systems using a temperature-dependent fluorescent dye. Analytical Chemistry, Vol. 73, No. 17, pages 4117-4123, Sept. 1, 2001.
** J.J. Shah, M. Gaitan and J. Geist. Generalized temperature measurement equations for rhodamine B dye solution and its application to microfluidics. Analytical Chemistry, Vol. 81, No. 19, Oct. 1, 2009 (published online Sept. 1, 2009).
Michael E. Newman | Newswise Science News
CWRU researchers find a chemical solution to shrink digital data storage
22.06.2017 | Case Western Reserve University
Warming temperatures threaten sea turtles
22.06.2017 | Swansea University
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
Germany counts high-precision manufacturing processes among its advantages as a location. It’s not just the aerospace and automotive industries that require almost waste-free, high-precision manufacturing to provide an efficient way of testing the shape and orientation tolerances of products. Since current inline measurement technology not yet provides the required accuracy, the Fraunhofer Institute for Laser Technology ILT is collaborating with four renowned industry partners in the INSPIRE project to develop inline sensors with a new accuracy class. Funded by the German Federal Ministry of Education and Research (BMBF), the project is scheduled to run until the end of 2019.
New Manufacturing Technologies for New Products
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
22.06.2017 | Medical Engineering
22.06.2017 | Life Sciences
22.06.2017 | Life Sciences