Early Prototypes

The prototypes used liquid liquid latex painted in layers onto a plastic sheet. While the final layer was tacky I'd lay out tiny SMD LEDs and let everything dry. From there I'd hand solder super thin copper wire to create the circuit: 

Latex had challenges and was also prone to triggering allergies. For a fast majority of my early prototypes i moved to casting silicone skins to serve as the base. These were a combination of silicone cast into 3D printed molds and then backed with a hypoallergenic pressure sensitive silicone adhesive.  

For early circuit boards I began prototyping using heat resistant PVC sheets and copper foil. I cut the copper and PVC using a Silhouette 4, and then with transfer tape moved the copper onto the PVC. I then used solder paste and a home made stencil (made from a transparency sheet) to apply the paste and then place the LEDS and resistors using teeny tiny tweezers. Lastly, I heated up the solder paste using a toaster oven or low temperature griddle to create the solder joints. 

Flexible circuits, especially CLEAR flexible circuits are still in the early days, and not very accessible to makers. Also, are they ever truly flexible? A fun pathway I headed down was looking at material for the circuit traces themselves that offered ultimate results in being stretched, flexed, twisted and pulled. Through endless hours of googling I stumbled upon this tutorial led by Steven Nagels, Raf Ramakers, Kris Luyten, Wim Deferme for making stretchy and flexible circuits using Galinstan. 

I was absolute fascinated and began experimenting on my own. Unfortunately the materials used in the tutorial were largely only available in the UK and I didn't have a ton of drop on ordering the US options for Galinstan, the metal that is non-toxic and remains liquid at low temperatures. So I learned how to smelt metal.

The copper foil circuits were unreliable and fragile as well as not easily produced. I began exploring making circuits using a screen printing method and conductive ink. While this method made production significantly faster, conductive inks turned out to be too costly for a small scale product. 

Once I had a better idea of what was required from a battery and component perspective I was able to move onto producing professionally manufactured PCBs. I started with rapid prototyping with OSH part but have since moved onto more economical manufacturers such as PCBWay and JLC PCB. 

Batteries have always been a huge challenge for Sprite Lights. They need to be thin, flexible, and most of all SAFE as they sit very close to the skin.

Sprite Lights is excited to partner with ZINERGY to incorporate a flexible and super safe battery solution. ZINERGY's batteries run at a low power of 3V and unlike lithium-ion batteries produce zero heat while running.  Through the use of a cutting edge screen printed battery compound, they can be bent squished, and even punctured without posing any risk of burns or injury to the wearer.

Learn more about ZINERGY here: https://zinergy-power.com/ 

The late stage prototypes combine a medical grade silicone based tape, flexible professionally manufactured and reflowed flexible circuit board, flexible ZINERGY battery, and waterproof artwork.

These Sprite Lights are single use and last a minimum of 6-hours. A Kickstarter will launch in spring of 2024 and feature a stunning galaxy compass design.