It’s summertime — have you been able to enjoy the feeling of sand between your toes as you take in the crashing waves? Walking barefoot on the beach can be a freeing feeling — well, that is until you step on a sharp shell! One new innovation, utilizing adhesive technology, aims to allow you the freedom of sand between your toes while simultaneously protecting the soles of your feet: NakeFit.
NakeFit is an adhesive sole that fits on the bottom of your foot and allows you all the advantages of going barefoot without the risks or lack of comfort. We aren’t surprised to see a product like this come to market when we regularly hear about barefoot running. We do, however, want to explore this neat product concept and tell you a little more about the science behind a product like this!
What ARE they?
We’ll admit, a lot of what made us ask questions about this product is the strangeness of it. Every other “shoe” (is this even a shoe?) has straps, buckles, or laces that hold it onto your feet. NakeFit is different, though. It sticks to your foot with a “hypoallergenic adhesive” and, according to the company, is also waterproof.
That got us thinking. How did the company make a product that can safely stick to your feet and also stay put all day long? That’s where polymer chemistry comes in. We don’t know what kind of adhesive NakeFit is using for this product (maybe we should test it!) but we can address the concept of adhesives in general.
There are several ways adhesives work. Some high performance adhesives actually react with the substrate to which they attach. This would not be a good operating mode for NakeFit because the user does not want the product permanently attached to their skin. Another method of adhesion is based on mechanical interlocking. In this mode, the adhesive flows into “nooks and crannies” and locks the adhesive to the substrate. The sole of a healthy foot does not have nooks and crannies and the adhesive on the surface of the NakeFit cannot flow so this is not the operating mode for NakeFit. Another method of adhesion is based on the polarity of substrates. Here a bond is formed between polar groups of the substrate with polar groups of the adhesive, not identical but a reasonable analogy to how opposite poles of magnets are attracted to each other. This is the likely operating mode for NakeFit and is also the reason why the adhesion is sensitive to prolonged contact with water.
Just like Polyvinyl alcohol (PVA) used in dishwasher pods, we weren’t surprised to find innovative polymer chemistry being used in everyday items, but we weren’t going to stop there. Next we wanted to learn about the soles of shoes. Again, NakeFit doesn’t list what materials make up their products, so we thought we’d learn a little about shoe soles in general.
The sole of a shoe is made to cushion force, add traction, and prevent things from cutting and abrading your feet. In many shoes, that’s where polyurethane comes in.
Polyurethane is another polymer that’s used in so many ways. From spray foam to furniture sealants, its strong and durable properties make it ideal for protecting your feet. Because it’s so light and abrasion-resistant, too, it makes a great material for the soles of shoes. Most of today’s sneakers and running shoes are made with either polyurethane or ethylene-vinyl acetate, more commonly known as EVA.
We’re curious – are you as eager as us to give NakeFit a try? They are currently hosting a kickstarter campaign and indicate they are working on the best way to distribute their product. Maybe by this time next summer you will be strolling the beach – more worry free than ever – thanks to NakeFit!
*Image from NakeFit