Carl Bugeja is a YouTuber who recently shared a pretty amazing project: a wearable heating vest with a flexible PCB.

On the front and back of the vest copper trace patterns inserted in the polyimide material create heating sources. The traces in total are around 30 meters in length. Additionally, magnets hidden beneath a shirt attach to metal stiffeners placed in the flex PCB’s edge to restrict the vest from flapping.
He used an ESP32 module to operate the heaters and communicate with a temperature sensor. Additionally, a seven-segment LED display serves as a debugging tool, displaying information such as the current temperature.

The temperature sensor is located too far away from the heating components to produce an accurate reading of the vest’s internal temperature.
The vest is powered by a single four-cell LiPo battery. Unfortunately, the battery has a tendency to drag the entire vest down from the back. While the magnets provide some resistance to the brick-sized battery, its weight remains a concern.
Bugeja acknowledges that the existing design is impractical. However, he has new design concepts for an improved design.

Take a look at the video for a full overview of the project.