ClearFlash was an acne device that used a photoflash bulb and a thin, darkened piece of metal to heat tissue, opening up pores and treating superficial acne. I was tasked with the electronics and the FDA pathway.
The first step was to find a predicate device, so that our device could be submitted using a 510k instead of a de novo submission. This saves massive amounts of time and money, as no clinical trials need to be done if you can show your device has similar parameters to the predicate. We found a few predicate devices and were able to Freedom of Information Act the prior FDA submissions and had a starting point for maximum and minimum parameters.
I designed the circuit based on a TLP65563 chip from Texas Instruments with a 200uF flash capacitor and an Excelitas photoflash bulb. The logic for the circuit was all controlled using flip-flops, as a microcontroller with firmware requires a more rigorous FDA approval process that hardware only doesn't. A single button and a simple flip-flop state machine allowed for charging and discharging, with an LED to indicate the status of the circuit: red -> charging, green -> charged.
The other challenges were:
- Making sure that traces were able to handle the current, as the discharge current is a few hundred amps, though only over a few milliseconds.
- Working with a mechanical engineer to mount the board and 9V battery in a custom, 3D-printed enclosure.