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Physics and Astronomy
Completed Project

Effect of Colored Dyes on Diffraction Patterns of C. elegans

Simone Karuga ’20 and Jenny Magnes (Physics)

Colored dyes are an ionic solid and have long sections of alternating single and double bonds. Their chemical composition allows their electrons to become excited using relatively low amounts energy. When the electrons return from an excited state to a ground state they produce an amount of energy that corresponds to a visible light wavelength, which we then see as a color. We investigated how dyeing water different colors affects the dynamic diffraction patterns that result from N2 “wildtype” C. elegans’ movement. Changing the color of the dye can serve as a way to control the intensity of the laser beam because not all of the light will pass through the dye. Using dye to absorb laser light can prevent oversaturation of the photodiode without using expensive optics, such as neutral density filters. We mixed one drop of dye into 40 ml of distilled water in a glass beaker and transferred the solution into individual cuvettes. Then using a Helium-Neon laser, an optical setup, a Picoscope oscilloscope, and a frequency analyzer, we investigated the frequency of C. elegans’ swimming motions. Red and yellow dyes absorbed less of the red laser light, causing higher amplitudes in the diffraction pattern. The green and blue dyes absorbed more of the red laser light causing the diffraction pattern to be dampened or undetectable. After changing the laser light from red to orange the diffraction patterns with the green and blue dyes became more noticeable. However, the orange line of our HeNe laser is dimmer than the red line causing the pattern to be harder to detect with the photodiode. Future research might include testing different colored lasers with the different dyes or testing the effects of concentration and type of dye on nematode health.