Riding bikes at night can be a bit sketchy, but all our hardcore cyclist friends love whipping through the streets with the moon at their backs. If you don’t have reflectors on your ride and are above wearing construction vests (but not above getting killed) then you may want to try your hand at constructing this jacket with a built-in turn signal from Leah Buechley, an Assistant Professor at the MIT Media Lab and inventor of the LilyPad Arduino. And if, for some reason, DIY isn’t your thing either, check out this reflective biking gear from We Flashy.
Some of the materials you’ll need include a LilyPad Arduino and power supply, FTDI connector, mini USB cable, 16 LilyPad LEDs, 2 push button switches, conductive thread and needle, a digital multimeter, a jacket or sweatshirt, fabric marker, puffy fabric paint, fabric glue and scissors.
The first step is to decide where each component is going to go on the jacket. Make a sketch like Leah’s above. Stitching for power (+) is in red, ground (-) in black, LEDs in green and switch inputs in purple. As you’re designing make sure to keep the power supply and the LilyPad close together for maximum voltage. Next, take a fabric marker (or chalk) and transfer your sketch to the garment. Attach the LilyPad pieces to your garment with double sided tape to aid in sewing.
Now trim the leads off the back of the power supply and stabilize your battery on the fabric by sewing or using glue—make sure to place it somewhere where it won’t distort or stretch the fabric. Sew the + petal of the power supply to the garment with conductive thread and then make small neat stitches over to the + side of the LilyPad, sewing it to the garment as well. Then tie your knots and coat with fabric glue to prevent unraveling.
Measure the resistance from the power supply + to LilyPad + and power supply – to LilyPad – using the multimeter. If the resistance is greater than 10 ohms, reinforce your stitching with more conductive thread. Once everything is working correctly, coat the thread with an insulator like puffy fabric paint. This will prevent the sewn traces from touching and shorting when the jacket is off.
Now sew in the left and right turn signals using the same techniques you used to sew the power supply to the LilyPad. Sew all of the lights’ + petals for both the left and right turn signals together and then sew to separate petals on the LilyPad (Leah used petal 9 and 11). Then sew all of the – petals of the lights together and then attach to the – petal on the LilyPad (Lead used petal 10). Refer to the sketch above if this gets confusing. Remember to seal each knot with fabric glue to prevent from unraveling. Then test your turn signals by loading a program (found in Step 5) to your LilyPad.
Find a place for your switches, like the underside of your wrists, which will turn your blinkers on and off. Push the legs of the switch through the fabric and bend them over on the inside of the fabric. Sew one leg to the switch input pedal on the LilyPad and then sew the leg diagonal to the first to another LilyPad pedal. Repeat on the other side. When you’re finished, reinforce with fabric glue.
Now sew a single LED onto the sleeve of each arm. They should flash to tell you what the back of your jacket is doing. Sew the + pedals of each LED to a LilyPad pedal and the – petals of each LED to the – side of the switch. Again, reinforce all knots with fabric glue.
Finally, program your jacket with the behaviors you desire. Leah’s code will turn each signal on for 15 seconds when the switch is pressed. Pushing the switch while the turn signal is on will also turn it off. Copy and paste the code into an Arduino window and then load it onto the LilyPad. Plug in your battery, insulate the rest of your sewing traces and hit the streets! FYI: Your garment is hand washable, just remove the battery first.
Visit the Instructables How-To for further instruction, more detailed photographs and tips on where to buy materials.