The Quest for a Truly Open Source Smart Ring

Smart rings may be finding their way onto more and more fingers as the years go by, but not everyone is happy with the options available on the market. Techies and hardware hackers, in particular, are frustrated by the scarcity of open source devices. Everything from the hardware design to the firmware is typically locked down, making customization virtually impossible for most people.

YouTuber KuoQuo is an engineer who would very much like to have an open source smart ring to hack on. However, since he couldn’t find anything for sale that was suitable, he decided to build his own. After inspecting some commercial devices, he discovered that the hardware inside a typical smart ring is actually not very complex at all. However, it does have to fit inside a very small space and conform to the shape of a ring—and that makes it very difficult for a hobbyist to produce.

Rather than getting caught up in these details, KuoQuo decided to first build a smart ring development board. This would have all of the components that his ideal smart ring would contain, allowing him to experiment with them and develop firmware. Squeezing everything into a smart ring could then happen at a later stage after doing some more research.

The board is powered by an energy-efficient Bluetooth-enabled microcontroller. Surrounding it is a collection of sensors connected over a standard I2C bus, forming a simple but flexible architecture. A motion sensor, specifically an accelerometer, handles gesture and orientation tracking, while a dedicated health sensor provides biometric data such as heart rate and blood oxygen levels, depending on the specific component used.

Power management, a huge concern for any wearable, is handled by a dedicated subsystem designed to keep the device running reliably. The entire circuit is implemented on a clean, two-layer PCB, with much of the design informed by reference schematics found in component datasheets. This approach keeps development accessible while minimizing unnecessary complexity.

Once assembled, the board successfully ran its first firmware. Using a smartphone app designed for Bluetooth development, KuoQuo confirmed that the device was broadcasting a signal, a key milestone indicating that the core system was operational. After that, the data pipeline was developed: sensors gather raw data, the microcontroller processes it, and Bluetooth GATT services transmit it wirelessly to a custom application where it can be visualized and interpreted.

Despite its relatively large size, the development board is an important first step. The ultimate goal is to miniaturize the design into a true ring form factor. That will likely require flexible PCBs and more advanced packaging techniques to accommodate the curved, space-constrained design.

KuoQuo aims to make the entire project open source, from hardware schematics to firmware. By doing so, he hopes to create a platform that others can build upon—something that stands in contrast to the closed ecosystems that dominate the current smart ring market.