You may be interested in a project published to the Hackster.io website earlier this year providing instructions on how to create a simple wearable heart rate monitor using an Arduino Nano R3.

Sweat it out: Novel wearable biosensor for monitoring sweat electrolytes for use in healthcare and sports. ScienceDaily . Retrieved June 2, 2025 from www.sciencedaily.com / releases / 2023 / 07 ...

Their study (DOI: 10.1002/smm2.1311) provides a comprehensive overview of the latest advancements in wearable heart sound sensors, examining sensor types, material innovations, design principles ...