Circuit2Yarn: From Planar Circuits to Electronic Yarns for Textile-based Interactions

Paper Title

Circuit2Yarn: From Planar Circuits to Electronic Yarns for Textile-Based Interactions

Publication Info

• Topic area: Smart textiles and electronic yarn fabrication
• Keywords: electronic yarns, smart textiles, flexible circuits, wearable electronics, interactive textiles, PCB components, capacitive sensing, IMU, LED matrix, textile integration

Background and Problem

• Problem / challenge: Existing methods for integrating electronics into textiles are limited by either the functionality of conductive yarns or the rigidity and bulkiness of PCB-based solutions. Achieving comprehensive computational capabilities in a yarn form factor remains an open challenge.
• Significance: Seamlessly embedding electronics into textiles could enable distributed sensing, actuation, and interaction across the body, transforming garments and everyday objects into interactive platforms.
• Motivation and related work: Prior approaches include conductive yarns for basic sensing, electroluminescent fibers for displays, and PCB integration for advanced functionality, but these methods compromise wearability, scalability, or accessibility. Recent advances in flexible PCBs and fiber computers offer potential solutions but remain complex or limited in scalability. This paper addresses the gap by combining PCB-level functionality with the softness and flexibility of textiles.

Solution

• Proposed approach: Circuit2Yarn, a fabrication framework that transforms planar printed circuits into flexible, yarn-like forms by rolling copper-traced TPU films with soldered components.
• Novelty:
  1. A low-cost, accessible fabrication pipeline for creating electronic yarns using desktop tools.
  2. Demonstration of diverse functional yarns (e.g., LEDs, sensors) as thin as 0.8 mm in diameter.
  3. Technical evaluations of yarn durability under bending, stretching, and washing.
  4. Application examples showcasing interactive textiles in everyday scenarios.
• Procedure and key techniques:
  • Design planar circuits using EDA tools.
  • Cut and transfer copper traces onto TPU substrates.
  • Solder components and encapsulate circuits with PDMS.
  • Roll planar circuits into cylindrical yarns.
  • Integrate yarns into textiles through embroidery, knitting, or weaving.

Results

• Concrete findings:
  • Yarn diameters as small as 0.8 mm were achieved, with up to 96.5% reduction in circuit width after rolling.
  • Yarns maintained stable resistance over 2000 bending cycles and 10 washing cycles.
  • Stretchability tests showed failure strains of up to 46%, with peak stresses of 1.5 MPa.
  • Capacitive sensing yarns achieved an average SNR of 13.27 dB.
• Advantage over baselines:
  • Comparable or superior routing density and functionality to industrial flexible PCBs, with greater accessibility and rapid prototyping capabilities.
  • Structural integration of electronics into textiles, maintaining softness and flexibility.
• Experiments / evaluation:
  • Mechanical durability tests (bending, stretching, washing).
  • Functional evaluations of sensing (IMU, temperature, humidity, light) and actuation (LEDs).
  • Application demonstrations in woven displays, garment drawstrings, tea bag strings, and musical instruments.
• Limitations and future work:
  • Current fabrication is manual and not scalable for mass production; automation is needed.
  • Integration of microcontrollers, power sources, and wireless communication remains a challenge.
  • Future work includes expanding functionality with medical sensors, energy harvesting, and sustainable materials.

Summary

Circuit2Yarn introduces a novel framework for transforming planar circuits into flexible electronic yarns, enabling the integration of advanced sensing and actuation capabilities into textiles. The approach combines PCB-level functionality with the softness and scalability of yarns, achieving diameters as small as 0.8 mm and demonstrating robustness under mechanical and environmental stress. Application examples, including a woven LED display and a gesture-sensitive hoodie drawstring, illustrate the potential for interactive textiles in everyday use. While current fabrication is optimized for prototyping, future work aims to address scalability and expand functionality, paving the way for widespread adoption of smart textiles.