ACerS member Zhong Lin Wang continues to make interesting progress on developing nanowire power generators and other energy-scavenging devices, and recently has demonstrated a nanogenerator that can be powered by the motion of a beating heart or the flexing of diaphragms and lungs.

When I last wrote about Wang in early 2009, he was demonstrating a “flex charge pump” generator constructed of zinc-oxide piezoelectric fine wires that measure three to five microns in diameter and 200 to 300 microns in length. Back then, he was thinking these tiny generators could be used in self-powered wireless sensing systems that gather, store and transmit data. He imagined then that his method could be scaled down to a nano size.

Since that time, however, it appears that Wang, a professor at Georgia Tech, has also become more interested in applications involving biomedical sensors. In fact, in a paper published in Advanced Materials, he and his fellow researchers report on what may be the first in vivo testing of nanoscale power generators activated by the breathing and heart beat of a rat. This could be a significant step forward in the creation of self-powered implanted nanodevices that could, for example, monitor blood pressure or blood glucose levels. (It should be noted that a group of Cleveland-area researchers reported in July 2009 on a larger-scale in vivo generator activated by a rabbit’s quadriceps).

Wang and his team sealed zinc-oxide nanowires in a polymer. The polymer served as a shield to the rat’s body fluids and to be a barrier to outside electrical sources. They then glued the 2 mm x 5 mm rectangular unit to the rat’s diaphragm muscle. The breathing motion generated 4 picoamps of current at a potential of 2 millivolts. Even more power was generated when the unit was glued to the rat’s heart: 30 picoamps at 3 millivolts.

Wang acknowledges that, while significant, this new work is more of a interim step than a final achievement, and that much more power is going to be needed for actual sensors. But Wang notes that his group has also figured out how to integrate a large number of nanowire energy harvesters into a single 4 mm² power source (a vertically integrated nanogenerator, or VING) and has demonstrated the feasibility with a self-powered nanowire pH sensor and a nanowire UV sensor.

Interestingly, Wang has also demonstrated a hybrid generation system that could be used in vivo. This system, used to power a UV sensor combines a piezo nanogenerator with a biofuel cell that scavenges biochemical energy (glucose/O₂).

Apparently the next step if to do in vivo testing of a VING–sensor system.

He is another video featuring an interview with Wang from about a year ago

Credit: Hanesbrands Inc.Hanesbrands Inc. reported today that one of their prototype jackets, known as the Champion Supersuit – a thin, high-altitude extreme weather coat made of ceramic aerogel nanotechnology insulation – has helped a climber make it to the top of Mount Everest.

Hanesbrands says that mountain climber Jamie Clarke, reached the summit of the world’s highest peak this morning. Clarke is quoted in a news release as saying, ““The Champion Supersuit did well.”

Hanesbrands – probably more associated with underwear than climbing gear – has been partnering with Clarke over the last two years to design and test innovative apparel. Along these lines, the company has been sponsoring a project called Expedition Hanesbrand has a special website covering the Clarke’s trek up Everest.

According to the website, at just 3 millimeters thick, the Champion Supersuit is the thinnest extreme-weather apparel gear ever designed and tested at high altitude on Mount Everest.

The garment is consists of four layers.

• An wind-barrier outer layer made of polyester fabric,
• An insulation Layer made of Element 21’s Zeroloft, a material licensed from Aspen Aerogel (based on  amorphous silica gel),
• A reflective layer of radiant foil to reflect body heat, and
• An inner wicking layer made of polyester.

Hanesbrands claimed in January that the Supersuit is “the first commercially viable application” of this Zeroloft Aspen Aerogel and “a breakthrough for the apparel industry.” They say this aerogel layer has four times the thermal insulation of goose down. (For the record, it should be noted that the Zeroloft’s website demonstrates what appears to be other commercial applications, such as jackets, insoles and sleeping pads. Maybe “commercially viable” is the key phrase. Aspen Aerogels also has a video of some of these applications here.)

Clarke’s ascent of Everest is apparently the climax of a 30-month R&D effort that involves aerogel and other high-tech wools and synthetic materials. The goal has been to develop a system of head-to-toe expedition apparel.

Element 21 is a company involved in creating applications that use high-tech materials in sports industry (e.g., golf and fishing) and obtained a manufacturing license from Aspen Aerogel for Zeroloft earlier this year.

Champion is Hanesbrands’ line of outdoor apparel. Russell Outdoors has also announced plans to work with Element 21 to introduce a line of Zeroloft outdoor clothing.

This is Bike-to-Work week and Bike Month in a lot of communities and cities across the U.S., and one of the accessories being increasing offered is a set of lightweight LEDs, added to a few of the spokes on your front or rear wheels, that are programmed to give the appearance of various designs and colors. Some of these LEDs can also be user programmed. All of them use “persistence of vision” to display a variety of patterns.

Keep in mind that these LEDs are no substitute for a good set of strong front and rear lights needed for bicycling beginning at dusk.

One the newest entries to this market is PIAA’s Ferris Wheel. According to Gizmag, the Ferris Wheel uses seven battery-powered LED lights to deliver 12 different pattern. They weigh 21 grams and sell for about $25, but currently are only sold in Japan. Here they are in action (note, in this and the other videos, the video frame speed makes the LEDs’ appearance look more choppy and varying than if seen live.)

The Taiwan-based Anvii markets Wireless Wheel Lights are a little pricier - about $100 – but they come with a wireless receiver for communications that can be used update lighting patterns and texts wirelessly via a USB connection to a computer.

Finally, I bring you MonkeyLectrics‘ Bike Wheel Light system the $65 unit (apparently a lot of riders use two per wheel, however) features 32 color LEDs available and cutting edge pre-programmed visual effects designed by our electronic artists. Powered by 3 AA batteries, the system can also be custom-programmed by the owner. Interestingly, MonkeyLectric also offers a Video Pro system for either bicyclists with a lot of money to show off their artisan skills, or  more likely – marketing companies who want to show videos on the wheels, stabile advertising messages and logos. The company saays all common image and video formats can be transferred from a computer onto the Video Pro. Media, playlists and realtime control can be customized to meet any application needs. The Video Pro costs $2,000.

Via Fast Company, artist-designer Wendy Legro’s concept for a mechanical/electronic LED “morning glory,” one-at-a-time or in an array, displayed at the Design Academy Eindhoven exhibition at Milan Design Week 2010:

[Legro] wants to reintroduce the sun’s natural source of light back into our lives. ‘morning glory’ consists of mechanical flowers which are triggered by a light sensor. by day, the flowers are closed, allowing the sun to shine in, and after sunset they open up and radiate light as they begin to cover the window.

Credit: Bok Yeop Ahn and Jennifer A. Lewis.

As you can see above, ACerS Fellow Jennifer Lewis and her team at the University of Illinois at Urbana-Champaign have figured out how to make intriguing and beautifully simple (yet complex) origami structures by bending and folding planar lattices. The lattices are made by extruding “inks” of ceramic, metal or polymeric materials using a precise, direct-write method.

In general, beads of inks are laid down in a particular pattern and allowed to partially dry. They are then trimmed, folded and finally annealed to complete the structure.

Direct writing of lattice. Credit: Bok Yeop Ahn and Jennifer A. Lewis.

But this makes it sound much too easy. In fact, Lewis,  Bok Yeop Ahn, David C. Dunand and others in her team faced significant materials and technical challenges. In a University press release, Lewis says, “Most of our inks are based on aqueous formulations, so they dry quickly. They become very stiff and can crack when folded.”

She says the challenge, then, was to find a solution that would render the printed sheets pliable enough to manipulate, yet firm enough to retain their shape after folding and annealing. The answer came by combining  wet-folding origami techniques (where paper is partially wetted to enhance its foldability) with special inks containing a mixture of fast- and slow-drying solvents.

The combination yields a lattice that can can be partially dry but flexible enough to fold through multiple steps. The origami crane - requiring 15 steps – allows them to demonstrate the agile possibilities of their methods.

For Lewis, a professor of materials science and engineering and the director of the university’s Frederick Seitz Materials Research Laboratory, these structures have a serious side. “By combining these methods, you can rapidly assemble very complex structures that simply cannot be made by conventional fabrication methods,” Lewis says.

Practically speaking, this technique could provide an alternative to existing “rapid prototyping” approaches to build scaffolds for tissue engineering. There are limits to rapid prototyping, which builds 3D structures by laying down layer after layer of material, due to the sagging of lower layers or compressing under their own weight.

Lewis’ team’s method could create light, strong structures that can be bent, folded and rolled out of lattices  formed from nearly any pattern. Stents, bone-repair scaffolds, biomedical devices or even catalytic substrates are possible.

Samples of stents and other structures. Credit: Bok Yeop Ahn and Jennifer A. Lewis.

Dunand says the next step is to try larger and much smaller structures and test ink compositions that would contain other ceramic and metallic materials.

“We’ve really just begun to unleash the power of this approach,” Lewis said.

A short video providing a closer look at some of the structures is available here.

Adding . . . Advanced Materials published a paper on this work, and if you look in the comments, the editor of the magazine has kindly posted a link for a free download of the paper.