New fibers have impressive capacitance

Jul 5, 2010 12:04 GMT  ·  By

One of the most promising aspects of future technologies are smart clothes, so called because they will be made up of intelligent fibers. These can be either high-resistance materials, such as Kevlar, or advanced polymers. But a group of experts has now created an even more interesting option, in the form of a very flexible wire, that exhibits 1,000 times more capacitance than a co-axial cable. The innovation could lead to the creation of advanced clothing in the future, Technology Review reports.

Some of the most important traits of smart clothes include the ability to “read” or otherwise sense the environment they are worn in. That is to say, they could for instance collect data on their wearer's heartbeat, breathing patterns and bodily temperature, thus constituting an advanced medical device. The instrument would also be capable of relaying data through a wireless connection to a receiver located in a hospital, for example. Additionally, sensors embedded in the fabric would also allow for kinetic energy to be harnessed, and then turned into electricity for various applications.

This can be easily done with piezoelectric devices. These are a very special class of materials, most commonly ceramics or crystals, that are capable of producing an electric potential when they are deformed. Multiple piezoelectric devices could easily transfer the energy they harvest through the high-capacitance wires, experts believe. Many researchers around the world have been working around the clock on developing methods of using the energy that the body expends while moving. The amount of electricity that can be produced as an average person walks over short distances can be used to power up a cell phone or a personal mp3 player, eliminating the need for batteries.

The new work was conducted by expert Jian Feng Gu, who is based at the Huazhong University of Science and Technology, in China. He and his group managed to create a simple rolled capacitor from a sheet of conducting polymer. The material is placed between two equally-long sheets of insulating material. The Chinese team chose to use low-density polyethylene for the job. The entire mix was then encased in a high-density polyethylene cylinder, which was heated up. The team then pierced a small hole in the container, and managed to extricate a thin wire from it, less than one millimeter thick.