Light-Up Hand Warmer (for cycling)

The light-up hand warmer for cycling is my first project using EL wires. I took particular interest in how this light technology could be applied to an activity that I do almost everyday. I was not at all familiar with EL wires, so I chose a medium — a woven hand warmer — that would allow me to easily and quickly get more comfortable with it.

The construction of the light-up hand warmer is very simple. I purchased an EL wire starter pack from Adafruit (Adafruit also carries many other colors; I chose red to match my bike and because red is a universal color for warning and stopping). The kit includes an EL inverter with a built-in battery compartment that also conveniently has a plug, so it can directly connect to the EL wire without additional soldering. As a bonus, the inverter has selectable modes of on, off, and fast/slow blink to conserve battery.

In order to maximize the light area of the EL wire, I threaded it through the sleeve’s woven fabric and bent it into a spiraling rectangle. The wire’s stiffness made it “fight” a bit against the softness of the sleeve, but in general the wire held its shape relatively well without distorting the hand warmer too much. When the EL wire was completed, I clipped the inverter to my jacket’s sleeve and pulled the hand warmer over everything.

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I was pleasantly surprised when I tested the light-up hand warmer in the field. First, because I had left no open ends of the wire exposed, I was able to avoid any snagging when I put on and took off my backpack. Second, the EL wire was more than sufficiently large and bright (I think) for drivers to spot it when I extend my hand for an upcoming turn or when I’m gesturing to slow down. The blinking modes came in handy, as it draws enough visual attention against a backdrop of countless lights in New York City. However, I still identified several key design areas in need of improvement:

  1. The EL wire slides easily through the woven fabric; alternative methods are needed to secure the wire in place…
  2. But it would need to be secured almost all along the length of the wire because its stiffness is making it protrude to the sides and bending awkwardly along with the varying hand positions.
  3. The inverter takes up a lot of space and its placement by the sleeve is not ideal; however, I don’t immediately see a solution to this that doesn’t involve bulky wire extensions (which may be safety hazard during riding).
  4. Although technically only one hand is required to signal both left and right turns and stopping, I should seriously consider making a pair of these as vehicular traffic is quite busy on the city’s roads. Expecting drivers to see an upcoming right-hand turn with a raised left hand is unrealistic.

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Overall, I am happy with the way the hand warmer came out as an exercise in getting familiar with the nuances of working with EL wires. Given more time, I would love to explore:

  1. A custom 3D-printed enclosure for the inverter that may function better as a cycling jacket attachment, with respect to slimness and security.
  2. A more distinctive light pattern that plays off of the topography of the hand.
  3. Various fabric materials to which EL wires can be sewn, either directly to the cycling gloves or to another accessory such as the hand warmer, that would improve shape retainment (along with different sewing methods).
  4. The use of alternative power sources (e.g. slimmer batteries) that would, again, allow me to cut down on the weight and size of the inverter.
  5. Ways for the pattern of light to react or connect in some ways to my physical activity; that is, its blinking pattern would no longer be pre-determined.

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