Sensor-based Stress Management Wrist Cuff

we want a sensor-triggered experience prototype.

Goal:
Build a wrist-worn cuff that can detect likely stress using basic physiological signals and trigger haptic breathing guidance automatically.

Core requirements:
• Wrist-worn cuff prototype
• PPG sensor for HR / HRV
• IMU motion sensor to reduce false triggers
• LRA motor + DRV2605 haptic driver
• Bluetooth connection to a simple app or logging interface
• Rechargeable battery

Detection logic:
• Rule-based, not AI
• Compare HR and HRV against user baseline
• Trigger only when HR rises, HRV drops, and motion is low for 60–120 seconds

Haptic pattern:
• Alert pulse
• 4 sec inhale ramp
• 0.5 sec pause
• 4 sec exhale pattern
• Repeat for 1–5 minutes

App/logging:
• Record trigger events
• Record HR/HRV before and after
• Allow user feedback after intervention

Important:
This does not need to be production-ready or medical-grade. The goal is to test whether automatic haptic intervention feels useful, natural, and trustworthy.

Deliverables:
A few working prototypes
• Firmware source code
• BOM
• Wiring/schematic documentation
• Basic data logging
• Haptic patterns adjustable in firmware