Importance of well adjusted illumination: using a flower to study a flower

Oct 11, 2015 • 12:18 AM UTC

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Microorganisms

Manu Prakash

I am a faculty at Stanford and run the Prakash Lab at Department of Bioengineering at Stanford University. Foldscope community is at the heart of our Frugal Science movement - and I can not tell you how proud I am of this community and grassroots movement. Find our work here: http://prakashlab.stanford.edu

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Note: this is a continuing post on a strange flower I had stumbled upon – if you have not seen the earlier post; try taking a look here first.
Light transmission through flower petals
Lookin at an organism with the help of the same organism.
This is going to be a cyclic post. We are going to use a biological organism to study itself. What I mean by that – is I will use a flower petal as a diffuser in the foldscope to image its own cells and figure out why it makes for such a great diffuser. I am already smiling – just thinking about it.
First; here is the demonstration to show why you need to think carefully and put together your illumination unit. It’s always valuable to compare – and that’s why Foldscope has a very open, modular structure. The image below is the same flower petal imaged with and without a diffuser between the LED light and the sample (on the bottom side of the Foldscope).

To the left is flower petal cells (buttercup) where I did not use any diffuser between the LED and the same. On the right – I played a clever trick – where I use tw flower petal itself as a diffuser. This is what the diffuser looks like.

Now; you can use many different type of diffusers like a simple tissue paper or diffusion tape (by 3M). The “invisible magic tape” by 3M is a nice diffuser. But the flower petal is a even better diffuser. This reduces chromatic aberrations significantly and you see internal skeletal structures inside the cells; that are completely invisible in the first image.

Here is a quick movie for you to enjoy beautiful cytoskeleton structures inside these curved cells.

Now; I was able to setup a time lapse on my foldscope and also watch these curved cells pop as a function of time. Here is a 8 sec movie where every frame was taken every 5 min and run for 2hrs.

Now; I am also excited about finding stomata on flower petals. I did not think about this before; but all flower petals seem to have some degree of stomata. If you have some insight on function of stomata on flower petals – please do drop a note below.

Now; I would love for anyone to suggest a live stain that I could use to stain the skeletal like fibers I see inside the petal cells. They seem to keep the cells pegged up and curved.
I have also noticed that over time; a lot of moisture actually collects on the petals themselves. They themselves act as little lenses.

Also, I can squash the cells and flatten them up to get to see structures inside the cells as well. Take a look.

Also; @Laks recent pointed about a paper that has looked at reflection properties of butter cups. Here is a link to the same.
“How does buttercup light up your chin”
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3350741/
So; next time you are Foldscoping – think about your illumination and never shy away from optimizing your illumination.
Keep exploring
Manu