Flutter PPG Health Monitor App

Project Description: I am looking for an experienced Flutter developer to build a PPG (Photoplethysmography) mobile application. I already have a fully functional web-based version (Javascript/Browser) that captures pulse and stress levels via the webcam. I need this ported to a native Flutter app to achieve medical-grade accuracy using better hardware control.

The Goal: Turn the phone’s camera and flashlight into a sensor to measure:

Heart Rate (BPM)

HRV (Heart Rate Variability - SDNN)

Stress Index based on RR-Intervals.

Key Deliverables:

Camera Sensor Module:

Implement the Flutter camera package to stream raw image data.

Crucial: Must handle "Torch Mode" (Flashlight ON) and Lock Exposure/White Balance to prevent signal noise.

Extract real-time luminance (brightness) data from the YUV/BGRA image stream.

Signal Processing & Math:

Convert raw brightness data into a clean waveform (Peak Detection).

Calculate BPM and HRV/Stress in real-time.

Note: I will provide the logic/formulas currently used in the web app.

API Integration:

Post calculated session data (Pulse, SDNN, Stress) to my existing REST API (pulse_stress table).

Biofeedback Module:

A "Therapy" screen that plays specific Audio/Video content.

The content must react dynamically to the user's real-time Stress level (e.g., changing visuals if stress drops).

Resources Provided:

Access to the existing Web App for reference.

All mathematical formulas for HRV and Stress calculation.

API Endpoints.

Ideal Candidate:

Strong experience with Flutter CameraImage streams and Isolates (for performance).

Understanding of basic signal processing (filtering noise from data).

Experience with real-time charting (e.g., fl_chart).