Implementation of a Batteryless Wearable Platform Enabled by AX-E0:
Introducing Velum

Autonomous Operation in Batteryless Wearable Devices: A Paradigm Shift

The evolution of wearable systems is not a matter of size or connectivity, but about autonomy—how technology can operate in harmony with the body, rather than demanding attention from it. A wearable must do more than measure; it must adapt, endure, and disappear into daily life. This solution explores how AX-E0 uniquely enables fully independent, continuous, and discreet wearable monitoring thanks to exceptional energy efficiency.

Introduction

How Batteryless Wearable Devices Work: System Overview and Objectives

At the center of this study is a minimalist wearable platform powered entirely by the body's own heat.

No battery charging, no connectors, no assumptions of user interaction beyond wearing the device.

Powered by the unmatched low-power capabilities of the AX-E0, the system continuously detects activity, classifies motion (walking or running), monitors vital signs (heart rate, SpO₂, temperature) and transmits data wirelessly, delivering timely insights while maximizing energy efficiency.

 

AX-E0 Microcontroller: Enabling Self-Sustaining Wearables

The key challenge addressed by this application is enabling indefinite device operation without user intervention.

Energy harvesting from a thermoelectric generator (TEG) sets the boundary conditions. The AX-E0's exceptionally efficient operating modes make it possible to maintain continuous data monitoring within these constraints.

All sensors communicate via I2C, including the heart rate and SpO2 sensor. Each sensor uses interrupt-based activation, leveraging AX-E0's deep-sleep mode with full data retention, drastically reducing power consumption while allowing near-instantaneous wake-up, crucial for responsive yet efficient operation.

Responsiveness also extends to skin contact detection. Instead of using additional hardware, the heart rate sensor employs an ultra-low-power proximity mode enabled by AX-E0’s optimized low-power states. This ensures minimal consumption during idle periods.

Upon contact detection, the sensor immediately transitions to full measurement mode, prompting AX-E0 to exit deep sleep and process incoming data rapidly — without compromising the energy budget — thanks to its industry-leading active mode efficiency.

AX-E0 Microcontroller: Optimized for Extreme Energy-Efficiency

The entire wearable platform is meticulously designed around AX-E0’s superior efficiency, specifically optimized for scenarios with limited and unpredictable energy availability.

Unlike conventional microcontrollers, AX-E0 is engineered to operate within the narrowest energy margins, activating only the strictly necessary logic blocks with ultra-fine granularity. Its architecture enables precise control of sensing and data processing, drastically reducing dynamic power.

This strategic energy management ensures reliable and continuous sensing and data transmission, even in extremely constrained energy scenarios, without compromising responsiveness or data integrity.

 

From Research to Application: Introducing Velum, Enabled by AX-E0

These principles converge in Velum, a cutting-edge wearable platform made possible by AX-E0’s ultra-low-power design. Operating solely on energy harvested from body heat, Velum transforms the theory of energy harvesting into practical, real-world applications for continuous monitoring. Its capabilities include:

1. Continuous skin temperature sensing for physiological monitoring;
2. Heart rate and SpO₂ measurement with automatic skin contact detection, selectively triggered through AX-E0’s efficient interrupt management;
3. Motion classification and step counting, continuously enabled by AX-E0’s minimal active power consumption;
4. Selectively activated Bluetooth Low Energy (BLE) connectivity, further leveraging AX-E0’s optimized communication handling.

Conclusion

A New Standard for Wearable Energy Harvesting Devices

This application demonstrates the concrete feasibility of continuous wearable monitoring powered entirely by body heat—uniquely enabled by AX-E0’s energy-optimized design.

By leveraging AX-E0’s exceptional energy management—from active sensing to ultra-low-power standby and deep sleep modes—continuous monitoring and reliable wireless communication can be maintained without batteries.

Velum embodies these architectural choices, clearly outlining the path toward truly autonomous wearables capable of indefinite operation. With AX-E0 at its core, Velum achieves intelligent, maintenance-free tracking of health and activity—seamlessly integrated into everyday life.