When I first got my hands on the foldscope, I was blown away. It was one thing to see someone else using it, and to see the images they got from it, but it was a whole new experience seeing it happen for myself. It seems almost impossible that such as small, simple device could do something so amazing. Many of the scientists in Mongolia I shared it with were equally amazed. The most amazing thing to me is the lens. The fact that a single lens can magnify incoming light by 140, 400, and even 2000 (as mentioned in Dr. Prakash’s papers) is extraordinary! Normally, that kind of magnification requires multiple lenses to achieve. And that got me thinking: can’t we increase this resolution further by just adding another lens on top of the foldscope lens?
Of course, the 2000x magnification cannot be further increased due to the diffraction limit of light. However, the 140 and 400x foldscopes can potentially be supplemented using another lens on top of it. Now this seems a bit difficult. The reason the foldscope is so cheap and simple, yet very rugged and durable is that it doesn’t have too many parts. It is flat and doesn’t have any extra breakable parts. So adding a second lens to the foldscope seems to mostly defeat the purpose. Then, the iPhone 7 came out. Though I’m more of an android user myself (All my microscopy images are taken with the Nexus 6P camera), the iPhone 7 gave me an interesting solution: use the camera to magnify the image. Now normally, phone cameras aren’t capable of real zoom – they use digital zoom, relying on a high resolution to prevent distortion when zooming. The iPhone 7, on the other hand, has a second camera that has 2x optical zoom. In other words, any image taken with the second camera is magnified by 2x. Thus, theoretically, if we use a camera with optical zoom to take pictures of our samples through the foldscope, we should achieve much higher magnifications. Note that magnification is multiplicative as it passes through multiple lenses, so the 400x taken with a 2x camera should result in an 800x magnification. Unfortunately, I don’t have access to such a camera at the moment, and thus haven’t been able to test my theory. However, I don’t see any major problems with my theory and highly suspect it to be the case. If anyone has access to any camera with optical zoom, please test my theory! (It is also entirely possible that this was already known, tested, and used.)
Another idea I had for modifications to the foldscope was to make it a fluorescence microscope. I am currently an undergraduate student at UCLA pursuing a degree in molecular biology. As such, fluorescence microscope are a key aspect of my work. Now, I understand that, for the most part, fluorescence microscopy isn’t really an important or useful aspect of microscopy for many people. Even for molecular biologists, they don’t really need flourescence viewing abilities in the foldscope because they will have access to it in their labs. For me however, the ability to modify the foldscope to view flourescent samples would be a great addition to my field research. It would also make it a much stronger educational tool, and could be especially more useful for medical diagnosics (staining with flourescent dye attached antibodies, for example).
The way to do this seems simple enough in theory. The light source must either be filtered, or changed so that it only emits a small range of light wavelengths. For example, a UV filter or a UV LED can be used to make sure the only light going into the sample is UV. Then, in front of the lens, we just need another filter that completely blocks the UV light and lets other wavelengths of light through. Or, more specifically, this filter must let the light fluoresced off the sample through (for this example, say the sample is GFP and thus emits green light), and completely block the UV light so that it cannot be detected by the observer/camera.
I am a lot less sure of this second idea. It relies entirely on whether or not the filter is good enough to completely block the undesired light. I haven’t had the time to test this one yet, but I do plan to do so soon. If anyone has suggestions, questions, or would like to go on and test my idea themselves, feel free to let me know and do so!