Full-body NFC: body-scale near-field sensor networks with machine-knittable meandered e-textiles

2025-03-17

AI Summary

Existing textile-based NFC systems suffer from severe electromagnetic interference induced by the human body, hindering simultaneous achievement of full-body coverage, ultra-low power consumption, and high data-rate passive sensing. To address this, we propose a full-body near-field sensing fabric fabricated via digital knitting with conductive yarns, featuring a novel twin serpentine differential spiral coil architecture. This design optimizes magnetic field distribution to enhance epidermal coupling, suppress deep-tissue eddy-current losses, and improve motion robustness. The fabric enables stable wireless power delivery and communication with passive sensor tags at arbitrary positions on the body. With less than 0.3% skin surface coverage, it achieves hundreds of kbps data rates and milliwatt-level energy efficiency—even under vigorous motion—supporting scalable, hundred-node, full-body passive sensing networks. This work establishes a new paradigm for unobtrusive, continuous health monitoring and activity tracking in daily life.

Technology Category

• Humans and AI: Brain-Sensing and Analysis
• Intelligent Robots: Multimodal Perception & Sensor Fusion
• Application Domains: Internet of Things, Sensor Networks & Smart Cities

Application Category

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

Abstract

Wireless body networks comprising battery-free on-body sensors and textile-based wireless readers can enable daily health monitoring and activity tracking by continuously monitoring physiological signals across the body. However, previous textile-based wireless networks made of coils or antennas have limited the data and power transmission area because covering the whole body results in undesirable levels of electromagnetic interactions with the body, degrading the scalability, power consumption, and data rate. Here, we report Full-body NFC, digitally-knitted electronic textiles based on a twin meander coil design that enables body-scale near-field communication (NFC) with battery-free sensor tags arbitrarily placed around the body. Full-body NFC features i) a meander coil that enhances the magnetic field intensity on the body's surface while suppressing undesired interactions with deep tissues, in addition to ii) paired identical coil structure that enables highly-sensitive and motion-robust NFC using a differential architecture. Additionally, industrial digital knitting machines loaded with conductive yarn allow the integration of the Full-body NFC system into daily garments supporting approximately $70-80%$ large-scale NFC-enabled area of the body. We demonstrate Full-body NFC could achieve mW-class energy-efficient near-field sensor networks with hundreds of kbps-class NFC battery-free sensor tags occupying less than $0.3%$ of the coverage area under severe body movements.

Problem

• Enable body-scale near-field communication for health monitoring.
• Overcome electromagnetic interaction issues in textile-based networks.
• Achieve energy-efficient, motion-robust NFC with battery-free sensors.

Innovation

• Twin meander coil design enhances magnetic field
• Industrial knitting integrates NFC into garments
• Differential architecture ensures motion-robust NFC