Solar energy has long been a symbol of progressive technology; these days, it’s also pushing the boundaries of fashion.
The Solar Shirt serves as a showpiece to demonstrate both the possibilities enabled by such collaboration as well as the capabilities of thin-film electronics in fashion. De Kok says it’s not quite ready for the commercial market yet – and that wasn’t the goal for this project – although new improvements are being made every day.
One roadblock to commercial adoption is simply the cost of production and materials. At Holst Centre, the modules begin as a roll of thermoplastic polyurethane (TPU). A Dek Horizon 03i roll-to-roll screen printer deposits DuPont 5025 silver conductor on top; a number of components follow, including an isotropic conductive adhesive from Henkel and the photovoltaic modules themselves. Another layer of TPU is placed on top to seal everything together. The modules can then be laser- or die-cut in the shape of the desired element and heat-pressed onto fabric. This process lends itself perfectly to a mass manufacturing model, but it’s not without its complexities – ones that add up in price.
Holst Centre is working to improve the technology by making it more stretchable and flexible. The problem lies mainly in the photovoltaic modules themselves, which to date aren’t stretchable. Rubber would be a preferable base material to plastic for a number of reasons – it’s more conformable and “textile-like,” says de Kok – but to date it’s not possible. If manufacturers could print directly onto rubber, this would also drastically simplify the production process and, again, the cost.
To the non-expert, the seemingly obvious question is: Why can’t they just print right onto the textile? If it works for T-shirts, shouldn’t it work for printed electronics?
“It’s certainly feasible,” de Kok says, but it’s not that simple. The problem is that textiles have a very open structure – that’s what we love about them. They’re breathable, flexible, foldable, and lightweight. But electronics require a continuous, uninterrupted layer in order to actually conduct electricity and function. De Kok says this leaves researchers two options: close up the structure of the textile (via flaps on the surface, for instance), or “manipulate the surface tension energies of the textile in such a way that the
electronics will stay on top.”
Despite its challenges, the Solar Shirt is unique in both the printed electronics and fashion worlds. “To date, all attempts to combine solar technology and fashion had focused on one-off, haute couture designs,” van Dongen says in a release. “We were able to seamlessly integrate the technology and the design so they mutually inform each other – advancing the concept and value of fashion. We’ve taken solar fashion from the catwalk to the high street.”
Pauline van Dongen’s designs combine fashion and function for an avant-garde look that comes in handy when you’re on the go. This Solar Shirt prototype was designed with photovoltaic cells from Holst Centre. Images courtesy of Holst Centre.
The potential for customization is encouraging, as well. Ton van Mol, Holst Centre managing director, says the modular ability of the roll-to-roll production gives designers “complete freedom.”
What’s next? De Kok says a large focus at Holst Centre right now is integrating organic and inorganic components to achieve the best of both worlds. Such products would then have both excellent conductivity as well as the rigidity to survive mechanical impacts. Possible applications range from medical imaging to car dashboards and more.
Van Dongen has her sights set beyond the realm of the smartphone. In a recent blog post, she quotes Syuzi Pakhchyan, a thought leader in the wearable technology world: “Our body is not a smartphone.” Pakhchyan sat on a panel with van Dongen at the recent South by Southwest festival in Austin, Texas. “There are so many more interesting, engaging, and subtler ways in which we can interface with and through our bodies,” the blog post continues, reminding readers of the importance of the human wearing the wearables. “Let’s replace ‘What does it do’ with ‘What does it incite us to do?’”
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