EMS Suit Elastic Conductive Thread Production

Title: Sewable, Insulated, and Elastic Conductors for EMS Suits: Production, Characteristics, and Application Advantages

Abstract

Electrical Muscle Stimulation (EMS) suits require advanced conductive materials that seamlessly integrate with textiles while maintaining flexibility, durability, and safety. This article introduces a novel elastic conductive thread tailored for EMS applications, detailing its production process, unique properties, and advantages in wearable electrostimulation technology. The thread combines high conductivity, insulation, and elasticity, making it ideal for integration into form-fitting EMS garments through sewing.

1. Introduction

EMS technology relies on delivering controlled electrical impulses to muscles via electrodes embedded in wearable suits. Traditional rigid wiring systems often compromise comfort, mobility, and garment durability. To address these limitations, a sewable, insulated, elastic conductor has been developed. This innovation enables direct embroidery into textiles while ensuring electrical safety, stretchability, and long-term performance.

2. Production Methodology

2.1 Core Conductive Structure

The conductor’s core comprises two components:

25 strands of ultra-fine copper wire: Each strand has a diameter of 0.05 mm, providing high conductivity while maintaining flexibility.

2 strands of copper foil wire (0.08 mm): These flat, ribbon-like strands enhance surface contact area, improving current distribution and redundancy.

2.2 Insulation Layer

The core is encased in a polytetrafluoroethylene (PTFE/Teflon) sheath, chosen for its exceptional dielectric strength, heat resistance, and chemical stability. The PTFE insulation prevents current leakage, ensures user safety, and protects the conductor from moisture, sweat, and mechanical abrasion.

2.3 Elastic Composite Structure

The insulated core is woven with:

Nylon threads: For tensile strength and abrasion resistance.

Spandex (Ammonia纶) fibers: To impart elasticity (≥150% stretchability).

A braiding machine interlaces these materials into a unified, stretchable conductor. The final product achieves a diameter of <0.5 mm, balancing slimness with durability.

3. Key Characteristics

3.1 High Conductivity

The hybrid copper core ensures low electrical resistance (<1 Ω/m), enabling efficient signal transmission for precise muscle stimulation.

3.2 Robust Insulation

PTFE’s non-reactive properties prevent short circuits, even under repeated stretching or compression. It withstands voltages up to 600 V, far exceeding EMS operational requirements (typically 20–100 V).

3.3 Dynamic Elasticity

The nylon-spandex braid allows the conductor to stretch synchronously with the garment, maintaining electrode-skin contact during movement. Fatigue testing shows <5% permanent deformation after 10,000 stretch cycles.

3.4 Sewability

Designed for industrial sewing machines, the thread integrates seamlessly into textiles without compromising flexibility or comfort.

4. Advantages in EMS Suit Applications

4.1 Enhanced Comfort and Fit

The elastic conductor conforms to body contours, eliminating rigid wiring that restricts movement—a critical factor for athletic or rehabilitation use.

4.2 Durability in Dynamic Environments

Resistance to sweat, friction, and repeated stretching ensures longevity, even with daily wear and machine washing.

4.3 Simplified Manufacturing

Direct sewing eliminates the need for adhesives or secondary bonding processes, streamlining production and reducing costs.

4.4 Safety Assurance

PTFE insulation prevents accidental current leakage, meeting IEC 60601-1 medical electrical equipment safety standards.

4.5 Customizable Design

The thread’s slim profile allows discreet placement within seams, preserving the garment’s aesthetics and functionality.

5. Conclusion

This sewable elastic conductor represents a significant advancement in wearable EMS technology. Its hybrid copper-PTFE core and elastic braided structure address the critical challenges of conductivity, safety, and durability in dynamic textile applications. By enabling seamless integration into garments, it paves the way for next-generation EMS suits that prioritize user comfort, mobility, and reliability. Future work will focus on scaling production and optimizing conductivity-to-elasticity ratios for specialized use cases.

Keywords: Elastic conductive thread; EMS suits; Sewable electronics; Wearable technology; PTFE insulation.