Digital fabrication enables future wearable electronics

Inkjet printing of highly conductive and cost-effective graphene-Ag composite ink for the digital fabrication of next generation wearable electronics

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With rapidly aging world population, the demand for wearable electronics is currently more than ever. The drive towards personalised and preventive healthcare in younger populations made such devices the norm for our daily life. Multifunctional wearable electronic textiles are seen as key growth area for multibillion dollar wearable electronics market due to their flexibility and comfortability. 

A personalized wearable garment that can interface with the human body and continuously monitor, collect, and communicate various physiological parameters (such as temperature, humidity, heart rate, and activity monitoring). Such device could potentially provide a solution to the overburdened healthcare system resulting from aging society as well as maintaining healthy and independent living for all, irrelevant of time and location. However, the current manufacturing processes for wearable textiles are complex and time consuming, and involved using of higher concentration expensive metallic inks.

Digital fabrication of wearable devices via inkjet printing is of great interest due to a number of advantages over conventional manufacturing techniques such as digital and additive patterning, reduction in material waste, deposition of a controlled quantity of materials and compatibility with various substrates. Moreover, the use of new exciting and multi-functional materials such as graphene in composite inkjet inks could be more sustainable approach, as it reduces the consumption of expensive metal inks and saves energy due to lower processing temperature of graphene-based formulations as opposed to higher sintering temp of metallic inks.  

Figure: Digital Fabrication of All-Inkjet-Printed Wearable Electronic Textiles

Here we formulated, characterised and printed a range of graphene-silver composite inks on printed electronic paper first in order to optimise the formulation for next generation wearable electronic applications. The sheet resistance of the printed patterns is found to be in the range of ~0.08–4.74 Ω/sq depending on the number of print layers and the graphene-Ag ratio in the formulation. We then inkjet-printed optimised graphene-silver composite ink on digitally surface pre-treated (reported in our previous study) textiles for highly conductive wearable e-textile applications. 

In order to demonstrate the suitability of the printed textiles for wearable strain sensor application, we mounted the printed fabric on a wrist joint and recorded the electrical resistance variation continuously during cyclic upward and downward bending of the wrist obtained almost repeatable response over a period of time and the capability of the printed textiles to capture mechanical events such as bending/unbending. Such inkjet-printed textiles will open up so many potential applications of graphene-based wearable e-textiles, where scalable and precise printing lines with higher electrical conductivity are desired.

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Nazmul Karim

Research/Knowledge Exchange Fellow (Graphene), National Graphene Institute

I am leading graphene textiles research activities at the University of Manchester, aimed at developing scalable and cost-effective 2D material-based next generation functional and wearable textiles. I have more than 10 years of academic and industry experiences in fundamental research, technology development and entrepreneurship. I also have a passion for getting research out of the lab and into real world applications. I am passionate about digital manufacturing of textiles (Textile 4.0), and the introduction of Smart Intelligent Materials and Artificial Intelligence (AI) to the textile industry. My research interests also include wearable electronics, flexible energy storage devices, and graphene-based high performance and smart composites.