Hello everyone,
I am working on an electronic Santur (a Persian hammered dulcimer) and need help designing an impact-sensitive sensor using the MPR121 capacitive touch controller. My goal is to detect both the intensity (force) and occurrence of hammer strikes on the sensor.
The problem:
The MPR121 works perfectly when I touch the sensor with my hand, but it does not detect hammer strikes (mallet hits) properly. I have tried different configurations, but the sensor does not respond well to non-conductive objects like my mallet. I need a way to make the sensor detect hits from external objects (mallets, sticks, or any non-human conductor) without requiring direct hand contact.
Current setup:
- MPR121 with custom capacitive touch sensor: Two aluminum foils with a thin plastic sheet between them.
- ESP32 microcontroller handling the I2C communication.
- Threshold values adjusted, but still ineffective for hammer strikes.
What I have tried so far:
- Lowering the Touch and Release Thresholds (Touch: 6, Release: 3).
- Adjusting Charge Time to improve sensitivity.
- Adding a floating ground to improve capacitive response.
- Changing the sensor material (thin copper tape, aluminum foil).
- Modifying the debounce settings for better impact detection.
What I need help with:
- How can I modify my capacitive sensor design so that it reacts to hammer strikes and not just hand touch?
- Are there any circuit modifications or material changes that could improve sensitivity to external impacts?
- Would an alternative approach (such as combining capacitive sensing with piezoelectric sensors) be more effective?
Any advice, suggestions, or alternative sensor recommendations would be greatly appreciated!
Thank you in advance! 
) it won't work for non-conductive objects