Build a Mobius Flex Using a Flexible PCB and ATmega328P MCU
The Mobius strip is a looped surface with only one side and only one edge, which has the mathematical property of being unorientable in terms of Euclidean space. (Avengers: End Game spoiler ahead.) In the movie Avengers: End Game, Tony Stark fashioned a Mobius strip wristband device that would allow his team to travel through time by entering quantum space. Without them, they could wind at the same point in space, only at different time intervals.
Electronics enthusiast Chris Miller also designed a Mobius strip wristband, and although you won’t be able to traipse through quantum space with it, you will undoubtedly draw attention while wearing it. As the definition states, Millers’s Mobius Flex is a single-sided flexible PCB outfitted with 60 0603 LEDs, which are controlled with an ATmega328P microcontroller.
To assemble his Mobius Flex, Miller used some flexible PCBs from OSH Park, which are made from a Polyimide substrate only 0.0762mm thick, and available in one or two layers. He then created a solder paste stencil out of mylar film for applying the electronics using a reflow oven, although he had to solder the LEDs on the backside of the PCB with an iron, enabling him to use the oven without melting the LEDs.
After completing the soldering, Miller then connected both ends of the strip by interlocking the copper fingers on both ends of the strip and then soldered them together. With assembly completed, the only thing left was to flash the board, and since the board does not have a USB interface, an ISP programmer such as AVRISP or AVR Dragon can be used instead. Those interested in Miller’s Mobius Flex can see a complete walkthrough of his build here.