3D printed microscope promises bigger, better science

Rema Krishnaswamy, determined to find a way to enhance the capabilities of the university microscope without spending lakhs of rupees, placed her bets on the open-source hardware movement.

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At home in Kolkata for a visit, Rema Krishaswamy spent many hours holed up inside her room, tinkering with some oddly-shaped plastic objects. On some days, her eight-year-old daughter Madhura would join her. This incited a fair bit of curiosity in the household, primarily from her octogenarian mother-in-law, a biochemist herself. 

She would ask her granddaughter what was happening, and when Madhura replied microscopy’, she would not believe it,” said Rema, now back to packed schedules in the bustling campus.

Rema frequently uses microscopes in her physics classroom at Azim Premji University. She finds them immensely useful to demonstrate the behaviour of physical systems, and expose students to optics. That is why she teamed up with her biologist colleague Sravanti Uppaluri to set up a microscope facility for their undergraduate students. 

Six years later, the facility is undoubtedly a hit. So much so that the ambitions of her research-inclined students occasionally overtook the capabilities of their microscope. This was a good problem to have, as far as she was concerned. 

All she needed to do was to figure out how to enhance the capabilities of their microscope without spending the lakhs of rupees that usually accompanies modifications. This is a common problem faced by universities and laboratories across the world, especially in developing countries like India. The open-source movement was born from this situation. 

The term open source’ is usually used to describe software that is freely available for anyone to use, modify and distribute. A common example is the Linux Operating System, as opposed to the expensive Microsoft Windows and Apple’s macOS. 

The concept of open-source hardware, on the other hand, was more complicated for reasons that are easy to imagine. Unlike software, hardware not only requires physical materials to assemble but also technical expertise and infrastructure to enable its manufacture. Despite these hurdles, there has been a boom in open-source hardware in recent years. How is this happening, and what would an open-source microscope look like? 

In 2011, while working at a field station in Thailand, Indian scientist Manu Prakash famously had the idea to develop a portable paper-based microscope costing less than a dollar and capable of achieving 2000x magnification. 

This very simple contraption would come to be known as Foldscope1 and prove to be remarkably useful as a teaching tool in classrooms, as well as in some research set-ups. Other do-it-yourself optical microscopes exist, but these are not universally practical and their capabilities are limited. 

Rema’s daughters Madhura and Anandi make an observation using the microscope. 

Rema had all these in mind while looking for open-source ways to surpass the current limitations of the University’s microscope facility. Eventually, she decided to place her bets on 3D printing, the now-common technology which allows us to create a physical object from a digital design. This technology was just the breakthrough needed by the open-source hardware movement. And it turns out, it is possible to print out a microscope! 

Fortunately, Rema discovered a design called OpenFlexure Microscope invented by Richard Bowman and his team in the UK. This design has been successfully adopted in several resource-starved scenarios, for example, malaria diagnosis in sub-Saharan Africa. 2

The OpenFlexure Microscope overcomes many of the weaknesses associated with 3D printed gadgets — the main one being the poor performance of printed plastic compared to manufactured metal parts. That is because printed plastic is soft, the surface finish is usually rough, and the printed object often does not match its nominal dimensions exactly,” say the creators.3 Instead, our design exploits the flexibility of the plastic by using a deformable mechanism to move the sample.”

In a news report4 about his project, Richard Bowman said that his project aims to build local capacity for manufacturing, rather than relying on charity. You can probably get someone to donate a microscope, but the problem is getting it serviced when it breaks or getting replacement parts or getting the right proprietary consumables,” he added. A ridiculous quantity of equipment is lying idle because it cannot be maintained.”

This sounds like a fantastic mission, but it will only mean something if scientists around the world test the OpenFlexure design and tweak it to their specific contexts. This is what Rema was trying to do while working from home in Kolkata. 

While having a readymade digital design is no doubt a significant advantage, adapting it to a workable product in India was never going to be straightforward. It began with the search for a good quality 3D printer. The one at the University would not do, and Rema realised that even the ones she found in small shops around Kolkata were not printing as well as she wanted. 

After days of trial and error, she finally identified a provider that was up to the task. The next challenge was the assembly of the printed parts. Rema and her daughter spent many days with the first version of the microscope, but it did not work. Often, the parts broke and they had to start again. 

The OpenFlexure instruction manual5, for example, asks for rubber rings called Viton O‑Rings that will enable some parts of the microscope to move (to move the sample, or to focus). However, Rema realised that these were not easily available in India. She walked in and out of many shops looking for specific kinds of rubber bands, before finally identifying something suitable. All that I am saying is, things are there on the website, but to get them working takes some time,” she declared.

The OpenFlexure microscope developers at work (Courtesy: CC-BY 4.0 Gathering for Open Science Hardware)

Sorting out the optics was the next, and crucial, step. The top-end version of the OpenFlexure microscope would require a microscope objective lens and the whole system could be controlled from a web interface connected to a Raspberry Pi (a small single-board computer) embedded in the instrument. 

But Rema wanted to start with something simpler and cheaper. The workaround she used involved detaching the lens found inside a common LED webcam and affixing it to the microscope. The trick is to take out the webcam lens and invert it. Your sample will just be 3 or 4 millimetres away, and the focal length of the lens is so small, that you can get a really high magnification. That is all there is to it, really!” she explained.

Onion cells, as viewed from the microscope

While her immediate motivation was university use, Rema has already begun collaborating with schools and diagnostic labs to introduce them to the enormous potential of the OpenFlexure microscope. Meanwhile, she continues her attempts at improving the microscope. Sometimes it is a bit fragile, so I have to find ways of making it more robust, maybe by printing some additional parts,” she said.

Rema demonstrates her 3D printed microscope at a college in Kolkata

The microscope is remarkably economical. The bulk of the expense is for printing, which cost Rema about INR 2,000. The camera cost her just INR 500. The whole set-up costs less than INR 3,000. Compare this with a regular microscope which would cost a minimum of INR 10,000. And you end up being so afraid it will break and fall that you do not give it to children. This microscope can be carried anywhere,” she emphasised. 

The day all the pieces came together was momentous, not just for Rema but for her whole family. The first image she took was of a drop of milk. Thrilled at the sight of the dancing fat globules, she asked her daughter to run and bring her mother-in-law.

Once the elderly woman saw that her daughter-in-law had indeed been building a microscope in her room all these days, all her previous scepticism disappeared. She cannot see that well, yet she remembered how to section a Vallisneria leaf with a blade and showed us the moving chloroplasts through the OpenFlexure microscope — this was an experiment she used to do when she was young. I cannot tell you what it was like to see an 85-year-old get so excited!”

References

1. Foldscope. https://​fold​scope​.com/

2. J. Stirling et al. (2020). The OpenFlexure Project. The technical challenges of co-developing a microscope in the UK and Tanzania. 2020 IEEE Global Humanitarian Technology Conference (GHTC), Seattle, WA, USA. 10.1109/GHTC46280.2020.9342860

3. Bowman, R., & Stirling, J. (2021). High-spec open-source microscopy for all. Physicsworld. https://​physicsworld​.com/​a​/​h​i​g​h​-​s​p​e​c​-​o​p​e​n​-​s​o​u​r​c​e​-​m​i​c​r​o​s​c​o​p​y​-​f​o​r​-all/

4. Eisenstein, M. (2021). Microscopy made to order. Nature Methods,18, 277‑1281. https://​doi​.org/​1​0​.​1​0​3​8​/​s​4​1​5​9​2-021 – 01313‑1

5. OpenFlexure instruction manual. https://​open​flex​ure​.org/​p​r​o​j​e​c​t​s​/​m​i​c​r​o​s​c​o​p​e​/​build

About the author

Nandita Jayaraj is a Science writer and Communications Consultant at Azim Premji University.