“It’s Your Experiment!” High School Science Teacher Conference 2008 (Oct 24th & 25th)

From the Michael Smith Laboratories

DIY microscope – MacGyver does Leeuwenhoek

with 2 comments

We have Gillian, a graduate student of Patrick Keeling, and Patrick himself running a session of how to make your microscope, specifically a Leeuwenhoek microscope. With practice you should be able to construct a workable microscope capable of somewhere around 100x to 200x maginification.

Bonus is that with this, you may also be able to discuss things like magnification, trigonometry, as you work out the capabilities of your lens.

I overheard Patrick saying that the true genius of Leeuvenhoek was that he made these lens by melting whilst everyone else was trying to grind the perfect lens.

Basically, in true MacGyver fashion, all you need is a pasteur pipette, paper, some Mac Tack, and (dum dum dum) a real live flame. Full list of stuff is below.

DIY microscope

First making the lens: (you can also buy premade lens at Efston)

1. Take a pasteur pipette. Pinch either end with finger and thumb, ad then place the middle in the flame. (Here’s the finesse part – that may take a few attempts). When the glass is soft, pull the pipettee apart, and this will create a thin strand of glass (see video below) – you can aim for a length of about one to two hand widths.

2. Once you have this strand, break off one end, so that you have a strand with a free end. This end you will place down into a flame (tilted an angle – if you have propane, great, but if not, you’ll need to hold the bunsen burner at about a 45 degree angle). Drop the strand into the flame, and you’ll see the tip melt upwards, collecting in a ball. If you leave it in there, it will continue melting upwards. Aim to produce an relatively spherical looking glass ball that is about 1mm to 2mm in diameter (see above video).

DIY microscope

3. Break at the stem about a cm or so away from the ball (the ball is your lens). This is then going to fit snuggly in between two pieces of cardboard, which will have a small hole drilled into them (say about 1.6mm – essentially small enough that the ball lens won’t fall out). Staple everything together so that the lens is trapped between the cardboard.

DIY microscope

4. Over the hole, you can also place some TEM grid over the hole so that a grid is visible whilst viewing. You used a “100 mesh squared grid – part # 1GC100” in class).

5. Just below the hole, put a small blob of thumb tack. Secure to this thumb tack, a cover slip. This is your bridge – by moving your thumb you can alter the plane of observation since the cover slip will move ever so slightly depending on how you gently contort the thumb tack.

DIY microscope

And voila – a DIY microscope!

Now… what can you do with this puppy?

Well, obviously, you can look at stuff. Feather strands are good. So is something like onion skin with a bit of staining. A hair. It’s kind of cool just to see the grid actually.

But if you want to get technical, you can also figure out the magnification of your lens. This is relatively simple, although you will need to create a contraption that can hold something like a laser pointer, and align your microscope with it. You’ll also need a dark room – the darker the better if your laser is weak (you can get pretty strong ones here – ask Patrick).

DIY microscope

Anyway, here’s a layout of of what you’ll see, and what you need to measure.

DIY microscope

And here is the equation you need to plug in.

DIY microscope

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Written by David Ng

October 24, 2008 at 12:00 pm

2 Responses

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  1. This is a great activity but I don’t think it worked out quite as well as it should have so can I ask for some advice? I used a Bunsen burner (mounted horizontally) and some capillary pipettes (pyrex). I could get a nice long filament (about 6″ long and the breadth of a human hair) but when I broke this and put an end in the flame, I don’t think my lens was getting big enough no matter how long I left it in the flame; the image through the lens was not very clear and the paper fibers were the main thing I was seeing. It seemed like, after the first 20 seconds or so, no matter how long I heated it, the lens refused to “grow.” Also, how DO you get a good clean hole through posterboard and card stock?

    Thanks for posting the videos, those were very helpful and thanks, in advance, for your reply!

    singingzoologist

    February 21, 2012 at 2:46 pm


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