Foldscope · S. mansoni 
We find ourselves again asking the same question: what is the simplest, most user-friendly way to view schistosome eggs with the Foldscope — a low-cost, paper microscope?
My friend at the Prakash lab, Anesta, recently asked a deceptively simple question: what about a reusable mesh filter? It made me want to re-approach the idea of a flat filter from a frugal-science perspective. Caring deeply about sustainability and accessibility, the question becomes one steeped in three things at once: materials, durability, and optics.
The constraints
Materials
Low-cost and accessible — nothing exotic, nothing hard to source.
Durability
Hard to break, easy to clean, good for many uses in a row.
Optics
You have to be able to see the eggs — not in shadow, not covered up, not too far from the viewing platform.
Mesh from Dr. Lee's lab
Sabona, in Dr. Lee’s lab, showed us a trick they use to filter cercariae out of water — nylon mesh. It turns out to be fairly affordable. We remain interested in PET and stainless-steel approaches, but for now, let’s give nylon some thought.
If it’s held taut — say, with a plastic tube melted onto it — it’s easy to clean. And when I asked about durability, a member of Dr. Lee’s lab just said, “I haven’t broken one yet.” Sold.
First, filtering
To review: we already know we can use a reusable acrylic coverslip with paperclips to reliably visualize the eggs — a thin, transparent stand-in for a quartz or glass coverslip.
So all that was left was to look at some eggs.
We thought of a few improvements, and we’ll test them soon — thank you, Phil, for helping us laser-cut some acrylic and PET!
While the eggs do catch, the viewing area becomes the next issue. We’re working to circumnavigate both the viewing area and the filtering process with a low-tech solution, currently in the works. Thinking caps are on.
Always follow through on dinner-napkin ideas — ideally next-day.
Until next time.
Frugal science runs on simple ideas.
Thank you for following the build. These lab notes are the messy middle of making diagnostics accessible — please share them with anyone who’d want a look behind the scenes of what this work takes.
