Please note that the MAX30101 PPG module was developed for finger applications and not for the wrist. But to improve measurements for wrist-based heart rate applications try the following optimizations:
1. If haven't done already, please use green LED. This is the recommended LED for wrist application as it is less susceptible to motion artifacts and you will get a cleaner signal compared to red and infrared (IR) LED.
2. Please try increasing the LED current and keep the wrist very still. In general, the wrist has a low blood perfusion index so it's more challenging to get a good signal, and the signal is more susceptible to any motion compared to the finger, for example.
3. Please try increasing the sample average. That will reduce the signal noise.