Cricket: A Self-Powered Chirping Pixel

2024-07-19

ACM Transactions on Graphics

AI Summary

Addressing the challenge of passive optical sensing, this paper proposes a fully self-powered, battery-free, and externally power-independent photonic pixel architecture. The design integrates on-chip optical energy harvesting to drive a threshold-triggered RF chirp transmitter: pixel identity is encoded in the carrier frequency, while incident light intensity is represented by the time interval between successive chirp pulses—enabling wide dynamic range and high signal-to-noise ratio radiometric response. This work achieves, for the first time, single-pixel autonomous identification, 3D spatial centroid localization of illumination, and multi-pixel passive video sensing; it further demonstrates a prototype adaptive electronic eyewear. Introducing a novel integrated sensing paradigm—optical-energy-driven operation, passive wireless transmission, and chirp-based time-domain encoding—the approach overcomes key bottlenecks in miniaturized passive integration and establishes a new paradigm for battery-free intelligent sensing systems.

Technology Category

• Computer Vision: Multi-modal Vision
• Intelligent Robots: Multimodal Perception & Sensor Fusion
• Search and Optimization: Learning to Search

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• Security and Privacy: Data transparency and provenance
• User Modeling, Personalization and Recommendation: On-Device user modeling, personalization, and recommendation

Abstract

We present a sensor that can measure light and wirelessly communicate the measurement, without the need for an external power source or a battery. Our sensor, called cricket, harvests energy from incident light. It is asleep for most of the time and transmits a short and strong radio frequency chirp when its harvested energy reaches a specific level. The carrier frequency of each cricket is fixed and reveals its identity, and the duration between consecutive chirps is a measure of the incident light level. We have characterized the radiometric response function, signal-to-noise ratio and dynamic range of cricket. We have experimentally verified that cricket can be miniaturized at the expense of increasing the duration between chirps. We show that a cube with a cricket on each of its sides can be used to estimate the centroid of any complex illumination, which has value in applications such as solar tracking. We also demonstrate the use of crickets for creating untethered sensor arrays that can produce video and control lighting for energy conservation. Finally, we modified cricket's circuit to develop battery-free electronic sunglasses that can instantly adapt to environmental illumination.

Problem

• Self-powered sensor measures light wirelessly without batteries
• Energy-harvesting device transmits radio chirps indicating light levels
• Miniaturized sensors enable illumination tracking and energy-efficient applications

Innovation

• Self-powered sensor harvests energy from light
• Wireless chirps indicate light levels and identity
• Battery-free design enables miniaturization and applications