In 2014, a group of scientists at Stanford University released Foldscope, a handheld microscope made almost entirely out of paper, which takes 30 minutes to put together, and which could capture images of cells. So far, millions of people – especially schoolchildren – around the world have taken images of the microscopic world with Foldscopes, while dozens of scientific studies have been conducted with the help of this instrument. Its cost? Rs 400.
Foldscope democratised the world’s access to optical microscopy. Now, researchers at Winona State University, Minnesota, have created a design for a ‘glowscope’, a device that could democratise access to fluorescence microscopy – at least partly so.
What is fluorescence microscopy?
An optical microscope views an object by studying how it absorbs, reflects or scatters visible light. A fluorescence microscope views an object by studying how it reemits light that it has absorbed, i.e. how it fluoresces. This is its basic principle.
The object is illuminated with light of a specific wavelength. Particles in the object absorb this light and reemit it at a higher wavelength (i.e. different colour). These particles are called fluorophores; the object is infused with them before being placed under the microscope.
There are versions of fluorescent microscopes with more sophisticated abilities, such as epifluorescence and confocal laser-scanning microscopes.
When the fluorophores fluoresce, a fluorescent microscope can track them as they move inside the object, revealing the object’s internal shape and other characteristics. For example, a fluorophore called the Hoechst stain binds to DNA and is excited by ultraviolet light. So a tissue sample collected from a person could be injected with the Hoechst stain and placed under a fluorescent microscope. When the sample is illuminated by ultraviolet light, the stain absorbs the light and reemits it at a higher wavelength. The microscope will point out where this is happening: in the nuclei of cells, where DNA is located. This way, the nuclei in the tissue can be labelled for further study.
Scientists have developed different fluorophores to identify and study different entities, from specific parts of DNA to protein complexes. On the flip side, fluorescence microscopes cost at least a lakh rupees, but often up to crores.
How does the new device improve access?
In the new study, researchers from Winona State University have described a rudimentary fluorescence microscope that they say can be put together at a cost of $30-50 (Rs 2,500-4,100). Many individuals in India may not be able to afford this, but schools and colleges can.
The scientists wrote in their paper: “We demonstrate the ability of these devices … to detect green and red fluorophores and to monitor and detect changes to heart rate and rhythmicity in embryonic zebrafish.”
Their setup consists of two plexiglass surfaces, an LED flashlight, three theatre stage-lighting filters, a clip-on macro lens, and a smartphone. The smartphone (with the lens attached) is placed on one surface that is suspended at a height (say, a foot above). The second sheet is placed below and holds the object.
A schematic diagram of the ‘glowscope’ setup. The components differ based on which fluorophore is being used. | Photo Credit: Schaefer, M.A., Nelson, H.N., Butrum, J.L. et al. A low-cost smartphone fluorescence microscope for research, life science education, and STEM outreach. Sci Rep 13, 2722 (2023). https://doi.org/10.1038/s41598-023-29182-y (CC BY 4.0 International)
In their study, the objects were zebrafish embryos in a petri dish, prepared according to well-established guidelines to ensure they aren’t harmed. They were injected with different fluorophores depending on which part of the embryos were of interest. The sources of illumination were also LED flashlights emitting light of correspondingly different wavelengths.
One of the stage-lighting filters was held between the flashlight and the object and the other two were held between the object and the smartphone. The role of these filters was to ensure that light of the right frequency reached the object and that fluoresced light of a suitable frequency reached the camera.
What did they observe?
With this setup, the researchers were able to image the creatures’ brain, spinal cord (using a fluorophore called DsRed), heart (mCherry), and head and jaw bones (mRFP). They were able to zoom in and out using the smartphone camera and the clip-on lens, and by adjusting the distance between the sample and the smartphone platforms.
The parts of the zebrafish observed using the setup shown above. The fluorophores used are (b) memGFP, (c) EGRP, and (d) EGFP. | Photo Credit: Schaefer, M.A., Nelson, H.N., Butrum, J.L. et al. A low-cost smartphone fluorescence microscope for research, life science education, and STEM outreach. Sci Rep 13, 2722 (2023). https://doi.org/10.1038/s41598-023-29182-y (CC BY 4.0 International)
The effect of using the clip-on macro lens while capturing a live video of the zebrafish. | Photo Credit: Schaefer, M.A., Nelson, H.N., Butrum, J.L. et al. A low-cost smartphone fluorescence microscope for research, life science education, and STEM outreach. Sci Rep 13, 2722 (2023). https://doi.org/10.1038/s41598-023-29182-y (CC BY 4.0 International)
They estimated the total cost of the setup used to obtain these images to be $30-50: $5-10 for the “scope frame”, composed of “plexiglass, wood, nuts, bolts, washers, paper clamps”; $10-15 for the clip-on macro lens; $3-5 for an LED lamp to generally illuminate the apparatus and $10-20 for the LED flashlight to illuminate the fluorophores; and less than $1 for the filters.
Is the ‘glowscope’ truly accessible?
It’s one thing to set up a fluorescence microscope using products purchased on online marketplaces; actually obtaining all of the materials required is another. Using a ‘glowscope’ still requires access to fluorophores, suitable biological samples, the know-how to combine the two, and some knowledge of physics to work out which LED flashlight to buy.
The Foldscope was truly remarkable because all its required components were simple to understand; preparing a sample for viewing was as simple as placing, say, a cloth fibre on a piece of paper and inserted that in front of the lens; and using a Foldscope was as simple as focusing its lens on the object. The ‘glowscope’ is not so simple.
However, the fact that a simple fluorescent microscope can be set up with a few thousand rupees means, instead of being entirely out of reach, researchers can prepare samples and take them to schools, where students can observe them. Students as well as researchers in resource-poor labs can also use Foldscopes and ‘glowscopes’ together to learn more about the microscopic world.
- In 2014, a group of scientists at Stanford University released Foldscope, a handheld microscope made almost entirely out of paper, which takes 30 minutes to put together, and which could capture images of cells.
- An optical microscope views an object by studying how it absorbs, reflects or scatters visible light. A fluorescence microscope views an object by studying how it reemits light that it has absorbed, i.e. how it fluoresces.
- In the new study, researchers from Winona State University have described a rudimentary fluorescence microscope that they say can be put together at a cost of $30-50 (Rs 2,500-4,100).
