The OpenFlexure Microscope is an open source 3D printed microscope that has been replicated in over 60 countries and on every continent. As they prepare to launch version 7.0, team members Joe Knapper, Julian Stirling and Beth Probert MBCS talk to Martin Cooper MBCS about OpenFlexure’s global impact and design principles as they aim for medical certification.
A microscope may be the most iconic piece of scientific hardware in the world. From classrooms to operating theatres, microscopy is a core technique, with principles largely unchanged in over 100 years. However, large areas of the world lack access to the equipment needed for teaching, research and healthcare. The OpenFlexure project uses 3D printing to produce an open source microscope capable of resolving parasites within blood cells.
Humble beginnings
This global project started in the office of Dr Richard Bowman, an optics researcher then at the University of Cambridge. After playing with a 3D printer, lens and Raspberry Pi Camera, initially just as a Friday afternoon project, it quickly became clear that the ability to easily build and modify a microscope had widespread appeal.
Whilst the design has evolved significantly since then, the core principles of the project remain the same: be open source and accessible for all. Today, different models of the OpenFlexure Microscope cost between £30 and £350 to build, delivering lab-grade performance at a fraction of conventional prices.
Accessible digital microscopy
As a digital microscope, it has no eyepiece. Instead, the OpenFlexure Microscope uses a Raspberry Pi Camera to capture images. With imaging performance equivalent to a 2000× manual microscope, the resolution allows users to see objects as small as one-hundredth the width of a human hair. While individual images can be great for teaching, Julian explains that the true power of the OpenFlexure Microscope lies in the scanning.
‘Our design allows the microscope slide to be automatically moved by the 3D printed stage. By controlling the motors and camera in Python, we can perform large area scans of samples automatically, building up huge composite images at high resolution. This is exactly what the microscopes in research labs and hospitals do all day - the difference is that you can build an OpenFlexure Microscope at home.’
Lessons from software development
‘Even though we are designing a microscope, functionally we are a software group’, Joe explains. ‘Each microscope uses a Raspberry Pi to run a server, and we use Python to control the camera, motors and illumination. The hardware design is also all code — we use a programming-based CAD package to design the 3D printed parts, which means we can use Git for version control!’
The OpenFlexure Project on Gitlab has tens of thousands of commits spread over many repositories. The open source nature of the project means that contributions vary in geography as well as scale; the custom PCB used to control the motors was originally designed by team members in Tanzania, while the most affordable version of the microscope was developed in collaboration with researchers in Argentina. ‘The breadth of the global community is what makes the project so special, from working with a maker-space in Kenya upcycling plastic bottles into microscopes, to advanced microscopy modes implemented by a research group in Japan’, adds Julian.
OpenFlexure and healthcare
While the OpenFlexure Microscope has been used for workshops, education and research, the team is aiming for even greater impact.
‘The current system of low and middle income countries (LMICs) importing their medical microscopes isn’t working’, Joe explains. ‘A huge proportion of imported or donated medical equipment goes unused as it cannot be serviced locally. Cancer and malaria kill over a million people per year in Africa alone, too often because reliable diagnosis just isn’t available. The OpenFlexure team is working with in-country manufacturers to enable local production of diagnostic microscopes.
‘The OpenFlexure Microscope has now been used for trials in a few hospitals. We’ve shown we’ve got the optical performance to enable pathologists to diagnose malaria and cancer, but that’s only part of the work. We also need to make sure that assembly can be quality managed, that the automation is reliable, the hardware can self-diagnose issues, and users trust the performance of a microscope that looks nothing like the traditional design.’
Software improving hardware
Precision is at the heart of microscopy, and the OpenFlexure Microscope achieves it through a combination of bespoke hardware and software. Joe explains how digital control and automation refine the Microscope’s performance and usability.
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‘The automated focus is a great example of where we needed to get creative with software due to running the server on a Raspberry Pi. Most ways of testing how sharp an image is are computationally expensive — we’d achieve a framerate of maybe three frames per second! But the Pi Camera gives us an MJPEG stream of images, and JPEG encoding is really efficient at lowering the file size when there’s less detail in the image. We travel to where the file size peaks, and there’s our sharp image!’
‘Similarly, cross correlation has been used in software to align images and audio for years. We use them to test how well overlapping images from our microscope match up — if the hardware of the stage is damaged, we can detect that in software before that microscope is used for diagnosis. We’re aiming for hardware-in-the-loop unit testing, so people can confidently replicate our device anywhere, regardless of experience.’
Getting involved
‘Our community grows daily’, says Beth. ‘People pop up on our forum all the time, with suggestions ranging from making the microscope cheaper to putting it into orbit. We’ve even seen our microscope turned into a laser fault injection tool for hacking computer chips! But the most common thing we hear is that people are concerned that they’re not an expert in optics, so can this project be for them?
‘OpenFlexure is an optics project, but also a computer science project, a medical project, an education project, an engineering project and a community project. No one is an expert in all of these things, but everyone can bring their experience, perspectives and curiosity to help direct the project. We’ve gone from a single lab in Cambridge to a global project, and we can’t wait to see where we’re going next.’
What’s the ultimate goal?
‘Medical certification!’ says Joe. ‘We want to support our network of engineers in Tanzania, Cameroon and Cape Verde to supply certified diagnostic microscopes to their communities. That’s how we maximise the global impact of our work and lead the way for other open hardware projects to fulfil their potential.’
For more information on the OpenFlexure project, including links to the documentation, designs and repository, visit openflexure.org or contact joe at joe@openflexure.org
