Smart Ring Wearable App Development with React Native

This development project exemplifies our proficiency in developing Bluetooth Low Energy (BLE), healthcare application development, and custom Internet of Things (IoT) solutions for wearable ecosystems.

Supported Device: Smart Ring (BLE-enabled)

Core Features (from store listings):

• Step counting, calories, distance, exercise time
• GPS map positioning with sports route tracking
• Sleep analysis (deep sleep, light sleep)
• Heart rate testing via the ring
• Care function (view others' historical data)
• Apple HealthKit integration (iOS only)
• Data encryption in transit, user deletion available

The goal of our client was to develop a cross platform mobile application that would connect with a smart ring via Bluetooth Low Energy (BLE) allowing users to monitor their fitness and sleep patterns. The key features/features/functionality that this app will need to provide are:

• Ability to see real-time and historical steps taken, heart rate, deep/light stage of sleep.
• Ability track where you walk, run, or cycle using GPS during outdoor activities.
• Ability for an individual to view other family members' health data, establishing a "care function."
• Ability to sync with Apple Healthkit (only on iOS devices).

Layer	Technology	Why
Frontend (Mobile)	React Native	Single codebase for iOS + Android; good BLE support (react-native-ble-plx); large ecosystem for maps and charts
Backend	Node.js (Express)	Lightweight, event-driven, excellent for real-time data sync and care function (WebSockets)
Cloud Infrastructure	AWS or GCP	Scalable: PostgreSQL (RDS/Cloud SQL), Redis for caching, S3/Cloud Storage for GPS routes
Local Storage	SQLite / AsyncStorage	Store offline BLE samples and user preferences
Apple Integration	HealthKit (iOS only)	Sync steps, calories, distance to Apple Health
Maps	React Native Maps (Google Maps / MapKit)	GPS route tracking and display

Workflow 1: BLE Pairing and Real-Time Health Data Sync

This is the core user journey – pairing the smart ring and viewing live/recorded data.

The smart ring's storage is limited; thus, the application has to accurately read and maintain Bluetooth Low-Energy (BLE) notification content. The app's offline-first SQLite database will help users avoid any data loss for upstream applications that require a mobile data connection when outdoors.

Process Flow 2: Tracking Your Sports Using GPS

The GPS map can provide real-time and historical position information about any activities performed using the App and let you store sport activities over time.

The following process is critical for consumers using GPS routing: The GPS routing and mapping function set this product apart as distinctly different from ordinary step counters. To accomplish this without draining the battery, you will need to manage BLE ring data with the phone's GPS in the background while providing a battery efficient way to track location.

4.1 React Native app to support BLE communications

Use the react-native-ble-plx library to communicate between app and the BLE Ring on iOS/Android.

You will need to create the following:

• Connection management using BLE devices advertising unique service UUIDs
• Connect and discover services/characteristics of connected devices
• Set up notification listeners to receive data on heart rate (standard characteristic 0x2A37) and custom step/sleep characteristics from your BLE ring
• Automatically reconnect every 30 seconds for 5 minutes if the ring goes out of range.

Offline-First Data Storage

Storing Structured Health Logs in SQLite & react-native-sqlite-storage

SyncManager

Background service using react-native-background-timer to upload records every fifteen minutes or when on charger.

Tracking GPS Routes

• Using react-native-maps for displaying maps.
• Using react-native-geolocation-service for accurate GPS (foreground and background).
• Requesting "always" permission for background locations, and adding NSLocationAlwaysAndWhenInUseUsageDescription for iOS.
• Storing each GPS position as {lat, lng, timestamp, hr_value} and storing the route as GeoJSON for cross compatibility.

Charts for Heart Rate and Sleep

Use either react-native-gifted-charts or victory-native to generate the line charts (which show heart rate over time) and bar charts (which show daily steps, deep sleep versus light sleep).

Sleep score will be calculated by an algorithm that combines the length of time someone spent in deep sleep and their percentage of sleep efficiency (the amount of time asleep divided by the amount of time they were in bed), and then will be displayed as a score (e.g., 85 out of 100).

Care Function (Viewing Another User's Data)

As defined on App Store: "Users may view another user's past data through the care function."

• User A sends a "care request" to User B (via email or phone number).
• User B accepts the request → a shared relationship will be created in the backend.
• User A will have a dropdown option to view "My Data" or "User B's Data".
• The data for User A and User B will be in readonly format and there will be no permissions to modify data.

Apple HealthKit integration (iOS Only)

• Use either react-native-healthkit or react-native-health to post to HealthKit for the following: steps taken, calories, distance, and heart rate for all steps are stored.
• Read from HealthKit will probably be Standard. The read from HealthKit is not mentioned in App Store. Standard procedure at HealthKit shows use of read-only access to view user data that you have posted on their platform.
• Permission handling for reading and writing to HealthKit (Steps taken, active energy, heart rate, distance walking/running) -- be sure to request permission to read and write step counts and active energy and heart rate to HealthKit as part of your integration.

4.2 Node.js - Back-End (Express)

• Lightweight, event-driven = great for handling the many concurrent uploads of BLE data from potential thousands of users.
• WebSockets = Real time information for caregivers (when family members upload new data instantly).
• Large ecosystem to support JWT token-based authentication and associated tools to implement token authentication in your application as well as tools to implement rate-limiting and ORMs for the DB (Sequelize and TypeORM).

4.3 Cloud Infrastructure (AWS or GCP)

Service	Purpose
Cloud Run / Elastic Beanstalk	Host Node.js app (auto-scaling)
PostgreSQL (RDS / Cloud SQL)	User accounts, care relationships, daily summaries
Redis (ElastiCache / Memorystore)	Rate limiting, caching user sessions, WebSocket state
Object Storage (S3 / Cloud Storage)	Store GPS route GeoJSON files, user profile pictures
CDN (CloudFront / Cloud CDN)	Serve route data and app assets globally
FCM + APNs	Push notifications (exercise reminders)

Scalability considerations:

• Health Ring users may sync multiple times throughout the day with the health ring; the back-end should support burst traffic (e.g., at 9 a.m. many users sync).
• Implement a queuing system like SQS (RabbitMQ or GCP Pub/Sub) to decouple data ingestion from aggregation of data.
• Auto-scaling rules - Scale up Node.js instances when CPU utilization exceeds 70% for a 3-minute period of time.

Feature (from store)	How We Build It	Technical Notes
Exercise timeline	Show amount of exercise per period (e.g., 10 AM: 200 steps)	Backend aggregates by hour; frontend uses horizontal bar chart
Steps, calories, distance	Pedometer from ring accelerometer	Calorie formula: MET value × weight (kg) × duration (hours)
GPS map positioning	Record sports route via phone GPS	Save as GeoJSON; polyline on map; color-coded by heart rate (red zones)
Sleep tracking (deep/light)	Ring accelerometer + heart rate variability	Algorithm classifies sleep stages; user sees horizontal timeline
Sleep score	Combine deep sleep minutes + sleep efficiency	Score 0-100; shown as gauge chart
Heart rate testing	Ring PPG sensor via BLE	Real-time display; historical line chart
Care function	View family members' data	User A requests access → User B approves → read-only view
Apple Health sync	Write steps, calories, distance to HealthKit	iOS only; requires permissions

Problems with BLE connection stability

Undertake to automatically reconnect with retry delay on a 5-minute scale; maintain local records when not connected

High battery consumption from GPS

Configure the significant-change location service to be used; only sample every 10 seconds while the phone is in a locked state

Provide real-time updates for caregiving functions

WebSocket connection via Socket.io when both users are active; send push notifications with the "new data available" message to the inactive user

The partition for permission granted to the application from Apple HealthKit

Warning message will be made visible; highlighting permission to access Health Kit with information related to the benefit of HealthKit will be present only in the app database.

Tracking identifiers required from the application are tracked by App Store

Implement App Tracking Transparency (iOS 14.5 and higher); only track users if they agree; provide the ability to opt-out in the settings

Users will be given the option to delete data

Provide for a soft delete with a 30-day retention policy (should the user wish to change their mind); to provide for the permanent removal of data, a scheduled job for deleting the data will be in place and will take place 30 days after a user's request.

No three-party sharing of information (Google Play)

Examine the use of all dependencies do not include ad networks or analytics that do not provide services; keep an eye on anything related to Firebase.

As an example, the use of Firebase Analytics would be acceptable. Note: Firebase is owned by Google, so a better approach would be to utilize hosted analytics systems like Matomo or not use any at all).

Our testing strategy covered backend, mobile app, BLE communication, GPS simulation, and real-device validation to ensure stability across the smart wearable ecosystem.

We utilized the Jest library to verify the functionality of our Node.js backend using unit tests and the React Native Testing Library for unit tests related to UI & navigation.

The BLE simulation was conducted with Raspberry Pi devices and mobile phones, whereas we used simulators/emulators to test the routes that were being followed by GPS devices.

CI/CD pipelines were established using GitHub Actions and Fastlane, which provided Automated Testing, Beta Deployment, and Cloud Deployment onto either AWS ECS or GCP Cloud Run.

Building the Smart Health Ring companion app with React Native and Node.js required advanced BLE communication, real-time health synchronization, GPS route tracking, and secure cloud infrastructure.

Core components of the solution include heart rate monitoring, sleep evaluation, support for HealthKit, CARE Functionality using WebSockets, and push notifications. PostgreSQL and Redis were used as databases.

Our development approach prioritized scalable IoT wearable app architecture, cross-platform performance, and compliance with Google Play and Apple privacy policies while delivering a seamless smart ring healthcare experience.

Google Play App Store