Embedding electronics into our clothing, footwear, or accessories is not a new concept. The next giant leap in this field, however, may lead designers to embed sensors in a fabric’s actual fibers—a core concept driving the e-textiles industry.
Two examples of e-textile research: a knitted heated glove (left) and light-emitting e-yarn (right). Image used courtesy of NTU
But the e-textiles market is a slow-rolling one for various reasons related to both commercialization and design challenges. What are researchers doing to overcome these barriers?
What Are E-textiles?
E-textiles refer to fabric or cloth with electronics “woven” into them. Because there are a number of ways to combine textiles with electronics, e-textiles fall into a number of categories: embedded e-textiles, laminated e-textiles, smart textiles, and smart fabric, to name a few.
This article focuses on e-textiles, specifically in medical applications, in which the circuit is wholly or partially integrated into the fabric, hindering its ability to capture sensor data.
An example of embedding technology into the fabric. Image used courtesy of Shi et al. and Fudan University
Using sensors, e-textiles can observe biometrics for fitness evaluation, continuously monitor chronic diseases, and supply and receive feedback from medical professionals without going to the clinic.
E-textiles can be beneficial when used in the healthcare industry for medical diagnosis and monitoring clinical conditions, especially telemedicine. In a previous article, e-textiles were even being tested for use in hospital bedsheets to monitor patients.
Roadblocks to Commercialization
A few of the challenges standing in the way of e-textile commercialization include flexible hybrid electronics, conductive fibers, energy-harvesting techniques, materials science, interference shielding, and manufacturability.
As for electrical engineers, these issues can be challenging to design around. Most EEs are quite accustomed to rigid circuit boards, reliable manufacturing processes, and silicon-based materials.
Reliability and Safety Considerations
Textile cables used to interconnect mediums for signal connectivity need to be safe, rugged, and durable. Reliability is a concern for wearable tech and e-textiles, and these devices must be unaffected by hostile environments like rain, snow, high humidity, and even washing.
Another concern is a reliable power supply. One way e-textile research is tackling this is with energy-harvesting technology. Other essential design considerations include higher power density, easy charging solutions, and high isolation.
A Washable E-textile Display for Medical Use
While designing e-textiles for garments and everyday apparel might be a long shot, this technology shows promise in healthcare and medical research. A group of researchers recently created a type of e-textiles capable of communicating, sensing, and supplying electricity to an illuminating display unit.
The researchers claim to have created the integrated textile system’s power supply using battery fibers that store energy from the photovoltaic textile module. They wove photoanode wefts with silver-plated conductive yarns to harvest solar energy.
By integrating the warps and wefts with battery fibers assembled from flexible MnO2-coated carbon nanotube fiber (cathode), zinc wire (anode), and ZnSO4 gel electrolyte, the researchers demonstrated both power generation and storage in the textile. The researchers also say the fabric is washable, which is crucial for commercializing e-textiles.
Demonstration of energy harvesting and storage module for e-textile. Image used courtesy of Shi et al. and Fudan University
When weaving the textile display, the researchers used ZnS phosphor electric field-driven devices. They also cite that such devices require only spatial contacts between wefts and warps to illuminate, making the fibers intrinsically durable and suitable for large-scale production.
A diagram for making this type of e-textile material. Image used courtesy of Shi et al. and Fudan University
They also designed a textile keyboard by weaving a low-resistance warp (silver-plated yarn) with a high-resistance weft.
This system was designed for people with voice or speech difficulties. The display systems can indicate a generic keyword about an individual’s mental state after decoding electroencephalogram signals.
Decoding mental state from electroencephalogram signals. Image used courtesy of Shi et al. and Fudan University
One drawback to this innovation is that it could be unsafe for practical use because the power supply needs to be below 36 V.
The Slow (But Promising) Future for E-textiles
From a usability and product design standpoint, e-textiles still seem to be a long way out from widespread adoption. However, with leading brands and even the military investing in e-textile development, this technology could one day move out of a primarily academic setting.
It’s likely, too, that commercializing e-textiles will require a fortified supply chain and awareness amongst engineers and suppliers about system integration challenges. These devices will also need to be streamlined through regulatory approvals to enter the market.
That said, while e-textiles aren’t likely to become a mainstream electronic item in households, they may appear more readily in medical settings as research—like that out of Fudan University—progresses.
Catch Up on Other E-textile Research
A lot of research is happening on e-textiles and smart clothing. Check out some of the most recent developments below.