We’re having some fifty young school children coming over to visit our research center in two weeks time. We thought it could be insightful and empowering to let each one of them assemble a microscope and view some brain samples with that microscope. While many research papers use a foldscope for that purpose, not all parents have a smartphone, and we want all children to carry home a microscope they can equally enjoy at home.
We thought of 3D printing them a variant of the OpenFlexure microscope that has no electronics - just some manual translation stages and an eyepiece for visual inspection. We will provide them with the parts, guide them step by step through the assembly, and finally let them have a look at the said cool samples.
Is it done? Can you share with us the respective design files of such a variant? All I found while searching the forum was this thread  for a microscope that uses a webcam instead of a Pi camera.
 Minimal manual version of the Openflexure microscope
Hi @lior, this sounds quite a challenge for 50 school children.
First to answer your direct question, the minimal manual microscope is at https://openflexure.gitlab.io/-/openflexure-microscope/-/jobs/4729744562/artifacts/builds/index.html . This is not a stable link, the manual version is not in a stable release and the location will change if I modify anything. This is unlikely in the next two weeks, but if the link does not work then go to the repository at https://gitlab.com/openflexure/openflexure-microscope/-/merge_requests/333 and click on the link where it says
View app. There are no specific instructions for assembling the manual version. The STLs for the modified body are in the
Customisations and alternatives section of the instructions, towards the bottom of that page. For the rest of the parts that you will need and the assembly instructions, it is best to follow the instructions for
Build the low-cost microscope. You will not need the parts related to motors, gears and cables. The web-cam optics are also not part of the main release yet. They are in the repository at https://gitlab.com/openflexure/openflexure-microscope/-/merge_requests/309, again use the
View app button to see that version of the instructions, and the parts for the web-cam are again in the
Customisations and alternatives section. Building the web-cam optics is similar to the
low-cost optics module - remove the lens from the web-cam and turn it round and mount in the
lens_spacer. However disassembling the web-cam is more complicated than for the Raspberry Pi camera. There are the start of some instructions for that at https://openflexure.gitlab.io/-/openflexure-microscope/-/jobs/3624024100/artifacts/builds/c270_preparation.html - again not a stable link. If you do end up using any of that, please do come back here with any questions where things are not clear.
There is not a version with an eyepiece in the main Openflexure project. There was someone on the Forum a while ago suggesting that they were going to try it. There are several reasons that we have not tried it as part of the main project. This is partly because the main design is for an inverted microscope, which is more complicated to configure with eyepieces. Also the z-motion stage cannot carry much load, and a system with eyepieces tends to be heavier than a small camera and will also be pushed by the user placing their eye to the eyepiece. It would certainly be possible to modify the upright version of the Openflexure microscope for direct viewing, but the performance (and cost) advantage is not as compelling as for a digital camera version.
If you have not yet made an Openflexure microscope then I would suggest that you try making the low-cost version - using the manual body if that suits, and a web-cam is getting a Raspberry Pi is tricky. The print time is quite long, even for the minimal manual version. This is one issue with a group of 50. The build is straight-forward with care, but it is not quick first time. Children are likely require help from people who have already successfully built microscopes - even if they are quite old. This again could be an issue for co-ordinating a large group. Whatever version of Openflexure microscope you end up using it will need illumination, which needs appropriate power.
I am probably coming across as quite negative, with fewer numbers and a longer timescale it sounds like a great idea. In this immediate timeframe I would go for a fewer microscopes, maybe 5 built as low-cost optics versions, if you can get the raspberry Pi s and if the resolution of a 20x lens on a conventional microscope is effective for your type of samples. Use the biggest, highest resolution screens that you can get to display the images for the groups, with one of your researchers guiding each group. It would not be the experience of building their own, but the live experience of seeing you searching a sample for the interesting items, and explaining what they are is actually stimulating. They can also try themselves - are there things that they can all try searching for? either all looking across the same slide, or each child having a different slide in turn?
Thank you very much for your prompt, thoughtful reply!
I overlooked the obvious fact that this is an inverted microscope ): Indeed it will not be suitable for a souvenir that a kid can assemble and take home, and we won’t have all the necessary parts shipped on time. We planned to give them a lecture + tour, and only came up with the microscope assembly idea yesterday.
Our graduate students undergo an optics workshop around April. Until now we let them assemble a simple fluorescence microscope from Thorlabs parts and image a sample with it. Maybe next year we could let them build the fluorescent flavour of the OpenFlexure microscope. We’ll build one ourselves first and see if it is instructive.
That leaves us with the following alternatives for the schoolchildren event:
Building this microscope from yet unidentified parts. I’ve emailed the author.
Attaching an eyepiece to a foldscope, as suggested in page 208 of this foldscope book.
Resorting to building a single highly capable microscope and showing its imagery on a large TV screen, or building a few such microscopes in teams as you suggested. I have a spare CMOS camera and a few objective lenses that can be used for this purpose, but the children will not be able to take the microscope home with them (they’ll get another souvenir anyway).
Let them build some other insightful 3D printable device.
We’ll keep on thinking how to do it right.
Thanks again for your extremely helpful reply,
The Openflexure microscope would be ideal for your graduate student workshop. I would try to build the bright field and fluorescent versions. It would be great if they were able to take one back to their lab afterwards, this is really what Open Science Hardware is about. The instructions for the fluorescence module are at present mainly in the Delta Stage, but the parts required for fluorescence are in the customisations page for the Microscope.
I don’t know Foldscope well, so I cannot really comment on your other suggestions for the school event. For option 3: if you are meaning to build an Openflexure device, a standard CMOS camera will not physically fit, and the sensor is not the optimal size. We strongly recommend the Raspberry Pi camera v2.1. The Openflexure optics are designed to make best use of the sensor size, and possibly more importantly the way in which the Pi camera is integrated into the Raspberry Pi hardware means that the Openflexure server has access to the video processing stream. We can implement live colour and flat-field correction and a fast auto-focus algorithm. For any other camera there is likely to be a strong colour cast. Compare the images before calibration https://openflexure.discourse.group/t/where-are-you-ofm-location-survey/771/44 and after calibration a couple of posts below that one https://openflexure.discourse.group/t/where-are-you-ofm-location-survey/771/47. Autofocus is also only available on the Openflexure Microscope with the Raspberry Pi camera v2.1. Without colour correction, flat field correction and autofocus it is not possible to use the motorisation to its fullest extent Automated Slide Scanning and Tiling.
Thanks a lot for all your help. We’ve decided to back down from building a microscope in such a rushed manner. For this year we’ll just 3D print them some optical illusions, discuss their relation to brain research, show them around our core facilities and give them a short talk on neuroscience research, crammed with cool videos. For next year we will definitely aim to letting them assemble their own simple 3D-printed or paper-folded microscopes, but will prepare for it well in advance and import the necessary parts.
Let’s touch base around December WRT to picking the right OpenFlexure microscope flavour for the graduate student course. If we do this right, we could disseminate a dozen such microscopes across our labs within three annual rounds of this course.
Have a lovely weekend,
Expanding on this here is an example of using the low cost optics vs a 40x objective as well.