Blood Smear under the Foldscope


An RBC smear stained with Giemsa acquired using a foldscope by Yash Jawale
Fig. 1. An RBC smear stained with Giemsa acquired using a foldscope by Yash Jawale

This past summer, together with the industrious Yash Jawale (BS-MS 2013) at IISER Pune, we began assembling the Foldscope. The high-mag and low-mag lenses were our two options that we were playing around with. Having the first device was super-exciting. However getting a reasonable image took some learning. Frame-grabs from the videos are what we finally settled on. Since we have research grade microscopes in lab, it seemed only reasonable to test the outer limits of what we could do with the Foldscope and compare them to these finely machined massive pieces of lab equipment.

The result (Fig. 1), while exciting, clearly suggests a need to further improve the image quality and light intensity. The sample is actually fairly purple in hue when viewed in our standard “college microscope” in 40x (Durga Instruments Co. Ambala, DICA). And we are still working on getting better pictures. Any suggestions are welcome.

What one can see somewhat are the two purple-ish dots in the equitorial plane center and right. These are the bonafide WBC stained nuclei! But to do more, such as morphology, we’d have to get a bit better with the lens, camera-work and the light.

Yash tells me that the new version of the Foldscope being shipped come with better lenses. This might help matters a bit, but maybe somebody in the Prakash Lab might have some ideas.

5 Comments Add yours

  1. laksiyer says:

    Hi. You should get fairly decent views of stained blood smears. The lens hasnt changed. Here are a few tips I found useful.

    1. Ensure that you have the condenser below.
    2, For even illumination you can also use a difuser tape (Scotch magic tape) instead of the condenser.
    3. What is the thickness of your coverslip? 0.13-0.17 is best.

    I have a few images of WBCs I took at the beginning of this year.

    Will try again
    Happy foldscoping.

  2. Manu Prakash says:

    Wonderful work. I like the fact that you calibrated your samples.

    For blood smears; we do use another high mag lens – but we don’t ship it in the kit as yet since we haven’t mass manufactured it as yet.

    It’s crucial to use either a condenser or diffuser tape to get uniform illumination. Also; for clean images at high mag; you want to use several tricks foldscope users have described before (including me); where the setup is not touched and is iMobile while taking images – see this link as well:


  3. Chaitanya says:

    Dear Manu, thank you very much for the quick response and taking time to address our issues.

    We will try to test the diffuser idea that you suggest with a scotch/tesa tape and see if we get better pictures.

    Indeed the scaling factor was got by using calibrated slides to get a digital image scaling factor (pixel to micrometer) and then using standard ImageJ tools (

    Dear laksiyer, thanks for the comment. I guess the ‘diffuser’ is something we clearly need to add to the light path. Our coverslips are 0.19 mm thick. How critical is this thickness? I can ofcourse source some thinner c.s.’s.

  4. laksiyer says:

    @Chaitanya. 0.19 mm would be problematic at high power. This is at the limit. I use 0.13-0.17mm. I think it is called No. 1 in coverslip circles. For my blood experiments, I just used tape.

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