David Kirkpatrick

July 5, 2010

The latest in smart textiles

The entire piece is a nice very short primer on the concept of smart textiles, but real news is a breakthrough in the very fibers smart textiles are woven from.

From the link:

But that’s a fiddly, time-consuming process. One thing that could help is more useful fibres. And today Jian Feng Gu from Huazhong University of Science and Technology in China and couple of buddies reveal one that could help.

Their idea is to create a simple rolled capacitor from a sheet of conducting polymer sandwiched between two insulating sheets of low density polyethylene. They then roll this sandwich into a cylinder and encase it in high density polyethylene.

There’s nothing unusual about this kind of rolled capacitor. But what Gu and co do next is. They heat it and then extrude it through a tiny hole to form a fibre with a diameter of less than a millimetre.

If the conditions are just right, the plastics all stretch in exactly the same way so that the internal structure of the fibre is just a smaller version of the original.

And that’s exactly what happens. Gu and co say their fibre is soft and flexible and has a capacitance some 1000 times greater than an equivalent co-axial cable.

February 25, 2010

Getting power from body movement

This study fits in with “wearable electronics” concept. For wearable electronics to be effective you need comfortably wearable juice to power those devices. Looks like some interesting medical applications here as well.

The release:

An electrifying discovery: New material to harvest electricity from body movements

IMAGE: “Piezo-rubber, ” super-thin films that harvest energy from motion, could be worn on the body or implanted to power cell phones, heart pacemakers, and other electronics in the future.

Click here for more information.

Scientists are reporting an advance toward scavenging energy from walking, breathing, and other natural body movements to power electronic devices like cell phones and heart pacemakers. In a study in ACS’ monthly journal, Nano Letters, they describe development of flexible, biocompatible rubber films for use in implantable or wearable energy harvesting systems. The material could be used, for instance, to harvest energy from the motion of the lungs during breathing and use it to run pacemakers without the need for batteries that must be surgically replaced every few years.

Michael McAlpine and colleagues point out that popular hand-held consumer electronic devices are using smaller and smaller amounts of electricity. That opens the possibility of supplementing battery power with electricity harvested from body movements. So-called “piezoelectric” materials are the obvious candidates, since they generate electricity when flexed or subjected to pressure. However, manufacturing piezoelectric materials requires temperatures of more than 1,000 degrees F., making it difficult to combine them with rubber.

The scientists describe a new manufacturing method that solves this problem. It enabled them to apply nano-sized ribbons of lead zirconate titanate (PZT) — each strand about 1/50,000th the width of a human hair — to ribbons of flexible silicone rubber. PZT is one of the most efficient piezoelectric materials developed to date and can convert 80 percent of mechanical energy into electricity. The combination resulted in a super-thin film they call ‘piezo-rubber’ that seems to be an excellent candidate for scavenging energy from body movements.

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ARTICLE FOR IMMEDIATE RELEASE “Piezoelectric Ribbons Printed onto Rubber for Flexible Energy Conversion”

DOWNLOAD FULL TEXT ARTICLE http://pubs.acs.org/stoken/presspac/presspac/full/10.1021/nl903377u