| 查看: 178 | 回复: 1 | |||
| 当前主题已经存档。 | |||
chl5063木虫 (著名写手)
流浪在小木虫
|
[交流]
超声波振动供能的纳米发电机
|
||
|
Using ultrasonic waves to vibrate an array of zinc-oxide nanowires, researchers at Georgia Tech have made a tiny generator that can produce direct current. By taking advantage of the fact that zinc-oxide nanowires are piezoelectric--they can convert mechanical energy into electricity--and by finding a way to collect electricity from multiple nanowires, the researchers have taken a big step toward a practical nanoscale power generator. "We can make each and every wire simultaneously and continuously produce electricity," says Zhong Lin Wang, a professor of materials science at Georgia Tech, who led the work. In a Science paper published this week, Wang and his colleagues demonstrate a prototype device, about two millimeters square, that generates around 0.5 nanoamperes of current for more than an hour. "The technique essentially provides a new method of power generation," says Pulickel Ajayan, a materials engineering professor at Rennselaer Polytechnic Institute. He says that the generator could be coupled with devices that are difficult or inefficient to power using conventional means. One important application is powering implantable biological sensors. According to Thomas Thundat, who researches nanoscale biological sensors at Oak Ridge National Laboratory, current battery technology limits the use of microelectromechanical sensors that measure cancer biomarkers, blood pH, and glucose. These sensors are getting smaller and smaller, but conventional chemical batteries can't keep up. "[The batteries] are huge and they run out of power...most of the time it's the battery that's big compared to the sensing part," Thundat says. "We have always been looking for very small power sources that don't need refilling." The new nanowire generator looks like a promising answer, he says. It could be implanted in the body, and, driven by muscle contractions, blood flow, or external vibrations transmitted through tissue, it could power the sensors. The generator could also drive nanodevices. Wang's research group has previously made nanowire pressure sensors that can detect extremely small piconewton forces as well as nanowire gas sensors. (See "A Nano Pressure Sensor."  Instead of an external battery, these devices could run on wind or water flow using the new generator. A key innovation that has led to the nanowire generator is a new electrode design. The surface of the platinum-coated electrode has a zigzag shape like the teeth of a saw: it has alternating parallel peaks and trenches. This zigzag electrode goes on top of an array of upright zinc-oxide nanowires, and its teeth can push many nanowires at the same time if it moves up and down. To vibrate the electrode, the researchers package the device, put it in water, and expose it to ultrasonic waves. As the zigzag electrode moves up and down, its peaks push and bend the nanowires, which generate electric current that the electrode collects simultaneously. "The wires can be compressed, can be vibrated left or right--it doesn't matter: all the current adds up in the same direction," Wang says. This is the first demonstration of a direct current output from nanowires that are driven by mechanical energy, says Charles Lieber, a chemistry professor at Harvard University. The new development is a "key step towards novel, cost-effective, adaptable, and mobile applications of nanogenerators in nanotechnology," he says. For real-world applications, the current generated by the nanogenerator would need to be higher and more stable. Wang's research group is working on improvements toward that goal. Right now, the nanowires are grown randomly, and the researchers estimate that anywhere between 250 and 1,000 nanowires contribute to the current. This is less than 1 percent of all the wires in the array, Wang says. An important next step is to grow a more regular array of nanowires that are uniform in size and height. Matching the nanowire pattern with the pattern on the electrode would utilize all the nanowires, increasing the current output and making it more stable, he says. The research team also needs to increase the generator's lifetime. It runs for a little more than an hour right now, and Wang says the researchers are not sure why it dies after that time. As a proof of concept, though, Thundat says that this work is a "major advancement in the power-generation area." |
回复此楼» 猜你喜欢
稀土发光分析｜核壳结构｜寿命拟合
已经有6人回复
-
稀土发光分析｜核壳结构｜寿命拟合
已经有0人回复
-
金属材料论文润色/翻译怎么收费?
已经有77人回复
-
稀土发光分析｜核壳结构｜寿命拟合
已经有0人回复
-
26 届青岛大学纺织化学与染整工程硕士（液体纳米分散染料方向）求申博建议
已经有4人回复
-
26 届青岛大学纺织化学与染整工程（液体纳米分散染料）求浙理工纺织 / 材料博导名额
已经有1人回复
-
敢问Acta Pharmaceutica Sinica B with Editor 三周了，能是什么情况？
已经有0人回复
-
求助 CeO2 Fe3O4 Cu2S CoFe2O4 标准卡 Jade 导出的数据
已经有0人回复
-
求助一篇MEMS散热器件文献
已经有0人回复
-
材化专业SCI论文（职称评定）
已经有0人回复
» 本主题相关商家推荐: (我也要在这里推广)
echo_8029
金虫 (著名写手)
- 应助: 3 (幼儿园)
- 金币: 1805.9
- 散金: 68
- 红花: 3
- 帖子: 1333
- 在线: 289.6小时
- 虫号: 265522
- 注册: 2006-07-15
- 性别: GG
- 专业: 无机非金属基复合材料
2楼2007-04-23 22:10:32
50