The Ateneo de Manila University Department of Physics’ Photonics Laboratory’s polarimeter setup, built mostly out of LEGO toy bricks, polarizing film, and cheap off-the-shelf electrical components.
Using simple circuitry, polarizing film, and LEGO toy bricks, an Ateneo de Manila University undergraduate physics student recently built an improvised polarimeter that can optically assess the purity of Vitamin C (ascorbic acid) and other chiral substances.
The device has potential applications in classrooms as a learning tool and may lead to more cost-effective means of monitoring the quality of some consumer products.
The Ateneo de Manila University Department of Physics’ Photonics Laboratory’s polarimeter setup is mostly made of LEGO toy bricks, polarizing film, and cheap off-the-shelf electrical components. SOURCE: Felicidario and delos Santos.
Polarimeters are invaluable laboratory instruments that can help infer the purity of a chemical by measuring the angle of rotation of polarized light that passes through the test sample. However, laboratory-grade polarimeters are prohibitively expensive, with a high-end model costing over $11,500 and a commercial manual polarimeter over $1,200.
Built at a small fraction of the price of a commercial polarimeter, the Ateneo de Manila University Department of Physics’ Photonics Laboratory’s setup features improved reliability and accuracy over the original design.
This makes their acquisition and use easier for small laboratories and classrooms in developing countries like the Philippines.
That may change thanks to the work of people like undergraduate physics student Ryan Joseph Felicidario and his thesis adviser, Dr. Ramon delos Santos, of the Ateneo de Manila University Department of Physics’ Photonics Laboratory. Their work improved on an earlier LEGO-based polarimeter built by Norwegian researchers Lise Kvittingen and Birte Johanne Sjursnes.
The Filipino researchers modified the original design and refined the detection process to obtain reliable and accurate measurements crucial for ascorbic acid, whose specific rotation is relatively low.
Built at a small fraction of the price of a commercial polarimeter, the Ateneo de Manila University Department of Physics’ Photonics Laboratory’s setup features improved reliability and accuracy over the original design. SOURCE: Felicidario and delos Santos
By using easily purchased items like LEGO® bricks, polarizing film, and cheap off-the-shelf electrical components, Felicidario lowered the polarimeter’s cost to just over $150. He tested the device using two over-the-counter samples of Vitamin C (ascorbic acid) from two different pharmaceutical brands. He compared the test results with known theoretical values for pure ascorbic acid.
While one of the samples produced values within the acceptable range, the other sample “showed significant deviations from the expected (values), suggesting possible impurities affecting its optical properties.”
“(The) comprehensive approach combining polarimetry and melting point determination proved to be cost-effective compared to other devices typically used for purity assessment, which are often more expensive,” Felicidario and delos Santos said in their paper, “Measurement of ascorbic acid samples’ optical rotation via an improvised polarimeter for purity assessment,” which was published in the Journal of Physics: Conference Series on October 23, 2024.
“Furthermore, the findings demonstrated that the polarimeter is not only effective in practical applications, but it also offers educational benefits. Its non-black-box nature facilitates a straightforward demonstration of optical activity and polarization concepts,” the paper concluded.