Tag Archives: Xiaodong Li

Bake and shake your t-shirt to make a flexible electronic device

I don’t think you actually need to shake but you do need to bake your cotton t-shirt, albeit in a special way, to create a wearable battery  or so the University of South Carolina’s Xiaodong Li says. Excerpted from the June 29, 2012 news item on Nanowerk,

Over the years, the telephone has gone mobile, from the house to the car to the pocket. The University of South Carolina’s Xiaodong Li envisions even further integration of the cell phone – and just about every electronic gadget, for that matter – into our lives.

“We wear fabric every day,” said Li, a professor of mechanical engineering at USC. “One day our cotton T-shirts could have more functions; for example, a flexible energy storage device that could charge your cell phone or your iPad.”

Li is helping make the vision a reality. He and post-doctoral associate Lihong Bao have just reported in the journal Advanced Materials (“Towards Textile Storage from Cotton T-Shirts”) how to turn the material in a cotton T-shirt into a source of electrical power.

I’ve been following the ‘wearable battery’ story for a while (the May 9, 2012 posting is the most recent) but Li’s approach is a little different.  Excerpted from the June 29, 2012 University of South Caroline news release by Steven Powell,

Starting with a T-shirt from a local discount store, Li’s team soaked it in a solution of fluoride, dried it and baked it at high temperature. They excluded oxygen in the oven to prevent the material from charring or simply combusting.

The surfaces of the resulting fibers in the fabric were shown by infrared spectroscopy to have been converted from cellulose to activated carbon. Yet the material retained flexibility; it could be folded without breaking.

“We will soon see roll-up cell phones and laptop computers on the market,” Li said. “But a flexible energy storage device is needed to make this possible.”

The once-cotton T-shirt proved to be a repository for electricity. By using small swatches of the fabric as an electrode, the researchers showed that the flexible material, which Li’s team terms activated carbon textile, acts as a capacitor. Capacitors are components of nearly every electronic device on the market, and they have the ability to store electrical charge.

Here’s what makes the approach different; it’s ‘green’ according to Powell’s news release,

Li is particularly pleased to have improved on the means by which activated carbon fibers are usually obtained. “Previous methods used oil or environmentally unfriendly chemicals as starting materials,” he said. “Those processes are complicated and produce harmful side products. Our method is a very inexpensive, green process.”

Somehow I’ve always seen ‘wearable batteries and/or electronics’ as opportunities for electrocution but I seem to be alone with this fear as there’s never any discussion about the safety issues might arise.

ETA July 3, 2012: Dexter Johnson in his June 29, 2012 posting on Nanoclast (a blog on the IEEE [Institute of Electrical and Electronics Engineers] website) notes that the simplicity of Li’s process may be specially exciting,

While Li makes mention of the environmentally friendly chemicals used to impart this capability to a t-shirt, it is perhaps the simplicity of the process that will likely be the most intriguing aspect to manufacturers.