In recent years, digital technologies have played a crucial role in enabling proximity-based communication between devices, particularly in the field of public health and the Internet of Things (IoT). One of the most widely adopted technologies in this context is Bluetooth Low Energy (BLE).

What is Bluetooth Low Energy (BLE)?

Bluetooth Low Energy is a wireless communication protocol introduced with Bluetooth 4.0. Unlike classic Bluetooth, which is designed for continuous data streaming, BLE is optimized for intermittent, low-power transmissions over short distances—typically within a few meters. This makes it ideal for devices that need to operate on minimal power, such as fitness trackers, smartwatches, beacons, and environmental sensors.

From a technical perspective, BLE follows a publish/subscribe model:

• The peripheral device (usually a low-power sensor) acts as the publisher.
• The central device (like a smartphone or hub) acts as the subscriber, connecting to and collecting data from the peripheral.

A single device can also act in both roles simultaneously, allowing for flexible peer-to-peer communication in mobile and embedded environments.

BLE and Exposure Notification Systems

BLE has also been a core component in the design of Exposure Notification Systems, developed globally to help manage public health risks during infectious disease outbreaks. These systems are built on frameworks such as the Exposure Notifications API, jointly developed by Google and Apple in 2020.

Here’s how the system works in principle:

1. Each participating device periodically broadcasts randomized identifiers over BLE.
2. When two devices are in close proximity, they exchange and locally store each other’s identifiers.
3. If a person later tests positive and reports it through an authorized channel, their recent broadcast identifiers are uploaded.
4. Other devices regularly check against these identifiers to determine whether a potentially risky exposure has occurred—without revealing identities or locations.

This decentralized, privacy-preserving approach made it possible to enable large-scale digital contact tracing while respecting user anonymity and consent.

BLE Beyond Public Health

While exposure notification was a high-profile application, BLE continues to power a broad range of innovations across industries:

• Smart homes: for controlling lights, thermostats, and appliances via smartphone.
• Wearable tech: for health monitoring and fitness tracking.
• Retail and marketing: through location-aware beacons that enhance user experience.
• Healthcare: in medical sensors and patient monitoring systems.

As BLE continues to evolve—especially with the development of Bluetooth 5.x standards—its importance in enabling low-energy, secure, and context-aware communications is only expected to grow.