EEG Recording App

A mobile Flutter application designed for polysomnography — comprehensive sleep studies.
The app records EEG signals from BLE devices, manages recording sessions, and integrates with a polysomnography service for automatic sleep stage analysis and hypnogram generation.

About the Application

The application is built for clinical and research sleep diagnostics. It supports full-cycle EEG acquisition during overnight sleep studies, including signal processing and server-based sleep stage prediction.

Supported features:

• Bluetooth Low Energy EEG device connection
• Real-time EEG data streaming and visualization
• Recording in TXT / CSV formats
• Uploading recordings to a polysomnography server
• Receiving sleep stage predictions (N1, N2, N3, REM, Wake)
• Hypnogram visualization and stage interval display

This application is intended for:

• Sleep laboratory environments
• Clinical EEG data acquisition
• Experimental sleep stage research
• Automated hypnogram generation workflows

Core Features

BLE Device Connection

• Scanning and connecting to EEG BLE devices
• Real-time connection state monitoring
• Custom device command support

EEG Recording

• Stream-based recording with buffering and time-based rotation
• TXT / CSV file formats
• int24Be format support (up to 8 channels)
• 50 Hz Notch Filter — power-line noise suppression for clinical accuracy
• Foreground service — continuous recording when the app is minimized

Signal Visualization

• Real-time display of up to 8 EEG channels
• Sliding window (3 / 5 / 10 seconds)
• Adjustable amplitude scaling

File Management

• Session and directory browsing
• File and folder deletion with session counter synchronization
• TXT preview and sharing support

Polysomnography Integration

• FilesPage — upload selected recordings
  POST /users/save_user_file

• ProcessedFilesPage — trigger prediction processing
  POST /users/save_predict_json

• SessionDetailsPage

  • Fetch hypnogram image
    GET /users/sleep_graph?index=N
  • Display sleep stage intervals

Data Requirements for Polysomnography

To ensure correct analysis by server-side models, the following parameters must be configured:

Parameter	Required Value
Sampling Frequency	100 Hz
Power-Line Filter	50 Hz Notch
Channels (TXT)	1 channel

Before recording:

• Set sampling frequency to 100 Hz
• 50 Hz notch filter is applied automatically during recording

Screen Flow

Connection → Recording → File Management → Processed Sessions → Session Details

The navigation follows a structured clinical workflow from device setup to sleep analysis review.

Data Architecture

EEG Recording Pipeline

BLE Device (notify)
    ↓
BleController.selectedDataCharacteristic.lastValueStream
    ↓
RecordingController.onDataReceived(bytes)
    ↓
EegParserService.parseAllBytes() → List<EegSample> (int24Be)
    ↓
Notch50HzFilter.process() 
    ↓
CsvStreamWriter.writeSample() 
    ↓
Файл: dd.MM.yyyy/session_N/session_N_dd.MM.yyyy_HH-mm.txt

Polysomnography Integration Flow

TXT/EDF (1 канал, 100 Гц, фильтр 50 Гц)
    ↓
POST /users/save_user_file (patient_id, patient_name, sampling_frequency for .txt)
    ↓
POST /users/save_predict_json (patient_id, file_index, channel for .edf)
    ↓
PredictResult(prediction, jsonIndex)
    ↓
GET /users/sleep_graph?index=N → PNG hypnogramm
    ↓
SessionDetailsPage

Installation & Setup

Requirements

• Flutter SDK 3.10+
• Android 5.0+ / iOS 11+ (для BLE и записи)

Installation

1. Клонируйте репозиторий и перейдите в каталог:

   cd eeg-recording-app

2. Установите зависимости:

   flutter pub get

3. Запустите приложение:

   flutter run

Polysomnography Server Configuration

1. Open:
   Settings → Polysomnography → Server Address

2. Enter your API URL, for example: http://192.168.0.174:8000/

The default server address is defined in: lib/core/constants/polysomnography_constants.dart

If your local network IP address changes, update the server address accordingly.

Project Structure

lib/
├── main.dart
├── core/
│   ├── constants/
│   │   ├── ble_constants.dart
│   │   ├── recording_constants.dart
│   │   └── polysomnography_constants.dart
│   ├── theme/
│   │   └── app_theme.dart
│   ├── utils/
│   │   ├── format_extensions.dart
│   │   └── signal_filters.dart           # Notch50HzFilter
│   └── common/
│       ├── eeg_sample.dart
│       └── recording_models.dart
│
└── features/
    ├── ble/                             # BLE connection
    ├── recording/                       # Recording and EEG visualization
    ├── files/                           # File management
    ├── polysomnography/                 # Polysomnography server integration
    ├── settings/                        # Settings: EEG, Server, BLE, Files Manager
    └── navigation/                      # App navigation

Dependencies

Package	Purpose
flutter_blue_plus	BLE connectivity
fl_chart	Signal visualization
flutter_foreground_task	Background recording
dio	REST API communication
http	Lightweight HTTP requests
get	State management and navigation