Introduction: The $1 Pocket Microscope - Explore the World Around You at 80x and 140x!
Judges Prize in the
Explore Science Contest 2017
Microscopes let you explore the world around you at a small scale. With this $1 3D printed microscope, you can see tiny things in amazing detail! Looking at insects, plants, and even dirt close up can be fascinating.
I've already seen firsthand how impactful inexpensive tools for scientific exploration can be. I started this design about two months ago when I wanted a cheap microscope to bring with me to Liberia, where I participated in a program training science teachers. Some of the teachers, particularly those from rural areas, had never used a microscope before. Using this very Pocket Microscope was the first time they saw the microscopic world firsthand!
This design is inspired by the Foldscope, a low-cost origami microscope which has the potential to open up the microscale world to millions of children and adults who may not have the chance to use a conventional microscope. I aim to improve upon several aspects of the Foldscope while maintaining affordability. The biggest problem with the Foldscope is that... you can't buy one yet! As of July 2017, it's still only available for pre-order.
The unique features of the $1 Pocket Microscope are:
- It's an open design that you can make entirely yourself.
- A pocket for a backlight is built right in. While you can just hold up the microscope to light, many more features are visible when a sample is illuminated with an LED.
- It offers a large field of view so that you can see your specimen easily.
A note about the magnification: The Pocket Microscope has two lenses: one which is 1/4" in diameter (80x magnification), and another which is 3/32" in diameter (140x magnification-- the same one as is used in the Foldscope, as far as I know). Despite the higher magnification of the small lens, I find myself almost always using the large one. The smaller the lens, the more light you need, the harder it is to focus, and the more you struggle to line up your eye, the lens, and the specimen. The large field of view of a 1/4" lens makes it easy to use, and 80x magnification is enough to let you see plenty of things that are invisible with the naked eye.
Read on to learn how to make your own Pocket Microscope!
Step 1: Assemble the Materials
Here is a list of the materials you need for the Pocket Microscope. In addition to these, you will need a 3D printer to fabricate the holder (or the ability to get creative and make it out of other materials). The holder will be described in the next step. With the exception of the glass balls, you may already have all the pieces at home!
While each part is somewhat expensive if you only buy one, they are quite cheap when purchased at a moderate quantity. Here's a cost breakdown for the essential parts for 100 Pocket Microscopes:
- 1/4" glass ball: $0.15
- 3/32" glass ball: $0.18
- Screw: $0.02
- Coin cell battery: $0.15
- Paper clips: 2x $0.006
Additionally, I use about 8m of 3mm PLA for the 3D printed holder. At about $0.07/meter, the plastic cost is about $0.42. All together, the materials are just about $1!
If you are on a shoestring budget, the only thing you really need to buy is the 1/4" glass ball. While you will compromise some features by not having all the parts, all you really need for a working microscope is that lens.
Step 2: Fabricate the Holder
3D printing is an ever more accessible fabrication technique for DIY enthusiasts. I designed the microscope body to be 3D printed, but it could conceivably be made from machined wood or plastic pieces as well.
Files for 3D printing:
You can expect some stringing in the battery pocket because of the overhang. Don't worry, you will break away the excess plastic when you insert the battery. I don't recommend adding supports because they will be difficult to remove.
With my Ultimaker 3, it took about an hour of print time per microscope. I had good results with 0.3mm layer height and otherwise default settings in Cura.
What if I don't have a 3D printer?
I've included a drawing with basic dimensions if you'd like to make the holder some other way. The dimensions don't need to be exact, really. Any mechanism of holding the lens less than 1mm from a specimen, and being able to move it up and down a little bit for focusing, would work.
Step 3: Assemble Your Microscope
Now that we have all the pieces, let's assemble the microscope.
Press in the lenses
The first step is to press the lenses into the 3D printed top piece. The 1/4" lens pops into the large hole, and the 3/32" lens is pressed into the protruding side of the small hole. Don't lose your small lens in its hole-- you want it sticking out slightly for good visibility.
If your big lens is loose, you can put a little bit of superglue at the edge to lock it in place. For very tight pieces where you cannot insert a lens with your fingers, try using a plastic mallet to force the glass ball into the plastic.
Screw together the two pieces
Next, join the top and bottom pieces with a 4-40 or M3 screw about 1 inch (25cm) in length. Use a screwdriver to drive the screw into the hole to form a hinge.
For some pieces that fit especially tightly, you may need to file away a little bit of extra material to make the top and bottom pieces mate properly. The hinge should be snug but too not tight.
Insert the paper clips
The paper clips hold your specimen in place. Insert them into the slots according to the photos. Use your fingers to flatten them.
Insert the battery
Next, take your CR2032 coin cell battery and insert it into the battery pocket. It's likely to require some force to push it all the way in, and you may break some plastic bits that filled the gap. Push it in as far as it will go.
Insert the LED
Carefully insert the leads of the LED on either side of the battery. The LED with only light when connected in one direction! If you have an LED with very long legs, you may need to trim them a little bit.
You may ask: are you shorting the battery by connecting it directly to an LED without a resistor? The answer is no, there is enough internal resistance in the battery for this not to be a problem. The LED will stay lit for days (though it only has a few days of useful brightness).
For long-term storage, you can put both legs of the LED on the same side of the battery. With no complete circuit, current will not flow.
Step 4: Prepare Specimens
You next need to find things to look at under your microscope. You will probably not need to look far-- even simple things can be fascinating! If you have nothing to start with, check out the corner of a torn piece of paper. Place your specimen under the lens and use the paper clips to hold it down.
Here are some tips for finding good specimens:
- The thinner, the better. If light cannot penetrate through your sample, you will have a hard time looking it at it.
- If you have a thick specimen where light cannot penetrate, look at the edge.
- When focusing, find a part of your sample that's easily distinguishable. If you're struggling to look at a fly, for example, find a leg and trace it back to the body. Or in a leaf, focus on a vein or imperfection.
- Trap tiny things in a sandwich of two pieces of clear tape, or a single piece folded over.
The Pocket Microscope is designed to hold a microscope slide in place, but you don't need to use a glass slide. A scotch tape sandwich works just as well. Just beware of air bubbles looking like something interesting.
Another tip: leaves dry out, so taping them down to a microscope slide preserves them for longer.
Step 5: Use Your Pocket Microscope
Now that you have a working microscope, go explore!
How to use the microscope
It's easiest to start to use the Pocket Microscope by looking through the large lens at a distance, at something that has an easy to see pattern. I found bamboo leaves to be particularly easy to start out with because they have large features.
In order to focus, move the arm up and down with your finger. If you're having trouble focusing, start with the lens touching your specimen, and slowly move it up until the subject is in focus.
Once you get a sense of how to focus the microscope and what being in focus looks like, hold it right up to your eye. The microscope should fill most of your field of view. You've been transported into the microscopic world!
What you can do with the Pocket Microscope
Everything looks so different on a small scale. What does dirt look like up close? How about sand? Dust? How does an fresh leaf compare to a dry leaf?
Microscopy lets you answer questions about the world around you by making observations. How do insects' feet enable them to climb upside down? Which bugs have hairs on their bodies? How does hair stay on your head? (Check out its roots) How does a flea bite its victim?
You can even flip out the top piece of the microscope and use the lens by itself. Put it against a computer or phone screen to see the individual pixels. How are different colors on the screen made with combinations of red, green, and blue pixels?
Try holding up a camera to the microscope to see what you can find. Enjoy, and share your photos!
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