I’ve spent this past week volunteering at PS Science summer camp, which brings a science lessons to elementary school students at underserved schools. The experience has inspired me to create a simple and inexpensive wearable project which can also be used to illustrate the bending of light in fiber optics. The project uses a 3D printed LED holder to connect 3mm color changing LEDs to short lengths of 3mm fiber optic cable. The resulting assembly can be attached to a headband, bow-tie, bracelet or clothing for a fun wearable take-home project.
Components:
- 3D printed LED/Battery Holder (https://www.thingiverse.com/thing:2976178)
- 3mm color changing LEDs (regular 3mm LEDs work too)
- 1/8″ or 3mm (total diameter) solid-core side-glow fiber optic cable
- CR2032 Battery
Directions:
Insert the 3mm leds through the holes in the sides of the holder as shown. Pliers are extremely helpful for this part. The long (positive) lead, goes through the top hole in the vertical “finger” that holds the battery, and the short (negative) lead passes through a hole in the bottom of the holder. Bend the positive lead up and around the “finger”. There is a vertical notch in the “finger” to keep it in place.
Pass the negative lead up through the hole in the bottom of the holder and down through the adjacent slit. Use pliers to bend the lead close to the bottom of the holder.
Once the LEDs are inserted, simple put the CR2032 battery into the holder with the negative side down. It should pop into place with only a little pressure. If it is hard to insert, you may need to bend the leads more or remove loose plastic from the holder.
Now using a sharp knife, cut the fiber optic cable into desired lengths – I used about 6″ for my project. The cables can be inserted into the different holes surrounding the LEDs for different shapes. You can make a bow, or “ears” or antennae if you leave one end of the cable loose.
Use the four vertical holes to attach the holder to wearable projects like headbands, bow ties, bracelets, etc…
When you want the LEDs to be turned off, the battery can be stored positive side down in the holder for safekeeping. If you’d like to combine this project with a lesson about light, there’s a simple and fun experiment here that uses a water bottle and laser pointer to demonstrate total internal reflection:
