How to make smart clothes

Ramses Martinez, faculty lead at Purdue’s FlexiLab

Ramses Martinez, faculty lead at Purdue’s FlexiLab

In the near future, all of your clothes will become smart, according to Ramses Martinez, faculty lead and assistant professor of industrial and biomedical engineering at Purdue University’s FlexiLab.

This is thanks to miniaturized electronic circuits and sensors that will allow you to seamlessly communicate with your phone, computer, car and other machines through your clothes.

Martinez and his team are focusing on “flexible electronics” in order to transform existing cloth items into battery free wearables that are resistant to laundry degradation and powered wirelessly through a flexible, silk-based coil sewn on the textile.

Fast Future spoke with Martinez about his work in using flexible electronics to make smart clothing.

Why the need for smart clothing?

Martinez: I have a smart watch. It has a bunch of sensors and looks nice on my wrist. So wouldn’t it be better if the sensing area were much larger as it could be with textiles? Textiles offer a lot of surface area — helping to separate the electronic components while still offering flexibility.

What was the main stumbling block to develop this?

Martinez: You need to have a power source. We had to mitigate the issue of having batteries attached to any sort of smart textile. Batteries are typically not very flexible, and they need to undergo constant recharging. In addition, they don’t behave well when you throw them in the washing machine. So we had to figure out how to input power sources in textiles that can then be washed several times without degrading performance.

What was the answer?

Martinez: We are constantly exposed to WiFi signals, particularly those who work in an office or those at the university, or even if you go to the mall. WiFi signals are everywhere. We thought we could have those signals generate enough power to run the low-power electronics embedded in a textile.

Getting WiFi to your cell phone uses metallic antennas, which are very good at tracking radio signals. However, they degrade when exposed to water. We made a metal-like material that is soft. We took organic materials, such as carbon nanotubes, and made a very fine dust that looks like printer toner. These particles are very conductive, and you can mix them with other material components and grow filaments that you can then thread together. We sew a silk-based coil into the textile and apply a hydrophobic coating to make it waterproof. It can be put into a washing machine. The resulting clothes are as flexible, stretchable and breathable as a cotton t-shirt.

What are the end results?

Martinez: We created a glove that can detect if a wire has a live current without touching it. The fingertips light up when a user is near a live cable to warn about the possibility of electric shock. Another is a miniaturized cardiac monitoring system sewn on a washable sweatband that is capable of monitoring the health status of the wearer.

We are also working on triboelectric textile interfaces that would enable the wearer to turn [the volume of] music up or down by touching the collar of a shirt.

I envision smart clothes will be able to transmit information about the posture and motion of the wearer to mobile apps. This will allow machines to understand human intent without the need of other interfaces, thereby expanding the way we communicate and interact with devices.

Purdue’s FlexiLab is also doing research into self-healing adhesives and self-powered, paper-based flexible electronics. You can read more about the research going on there by clicking here.