A Nano Pressure Sensor 一种纳米压力传感器

Zinc-oxide nanowires that respond electrically when bent could be used to measure minute forces and pressures.

Twist, bend, or squeeze piezoelectric materials, and they produce electricity--an effect that is used in microphones and telephones. Now, taking advantage of the piezoelectric effect in zinc-oxide nanowires, researchers at Georgia Institute of Technology have made tiny devices that can measure extremely small forces--in the nano-to-piconewton range. That's about the force involved in interactions between two molecules, says Zhong Lin Wang, the materials-science and engineering professor at Georgia Tech who led the research.

Being able to measure such small forces might lead to devices that could be implanted in the body to measure minute blood-pressure changes continuously, Wang says. The sensors could also be installed on the wings of airplanes and spacecraft to monitor very small pressure fluctuations. And because the current flow through the nanowire responds quickly, it could be used to make a sensitive trigger for car air bags. "If it's subject to an external force, then it turns off within a microsecond," Wang says. 【移植体内测量血压，安装飞机或飞行器监视气流压力波动，激发汽车气囊】

By connecting the two ends of a zinc-oxide nanowire to electrodes, Wang's group has made devices similar to the transistors in electronic devices. In an electronic transistor, applying a voltage to the gate electrode controls the flow of current between the source and drain electrodes. In the new pressure-sensing transistor, the two electrodes that the nanowire is connected to act as the source and drain, but there is no gate. Instead of applying a voltage at the gate, one simply bends the wire.

When the nanowire bends, the stretched outer side of the bent wire becomes positively charged, while the compressed inner surface becomes negatively charged. The difference in charges creates a voltage that substitutes for the gate voltage.

Zinc oxide is biocompatible, so one could implant the nanowire pressure sensor in the arm to monitor blood pressure continuously, Wang says. The sensor could transmit the pressure reading to a receiver on one's watch that displays the data.

Because the device is based on the deformation in a single nanowire, "one could think that the sensitivity can be very high," says Yi Cui, professor of materials science and engineering at Stanford University.

The concept could also be applied to other types of sensing. One use for the device could be as a biosensor, Cui says. The principle is that molecules striking or sticking to the nanowires would deform the wire and change the current through it. Researchers could also develop a chemical sensor, in which the chemical reaction disturbs the nanowire, says RPI's Lu.

The idea is at a laboratory stage right now, and the researchers still need to come up with a design for a self-powered pressure-sensor device. This engineering challenge might not be easy, Lu says. "The basic idea is pretty good," he says. "Exactly how you would do it--putting it in the body and getting the response, figure out what's the signal, what's the noise--that's always challenging."【纳米电机供电】

Western Logic

西方人的“强者”逻辑：

第一，你必须有实力；
You should have power!

第二，你必须证明你有实力；
You should certificate your power!

第三，你必须让别人明白，你有勇气和决心在必要时使用你的实力。
You should let us know you have courage and resolution to employ your power if necessary!

Researchers bend nanowires to create new class of electronic components

Mar. 1, 2007 Small Times

Researchers at the Georgia Institute of Technology have taken advantage of the unique coupled semiconducting and piezoelectric properties of zinc oxide nanowires to create a new class of electronic components and devices that could provide the foundation for a broad range of new applications. So far, the researchers have demonstrated field-effect transistors, diodes, sensors, and current-producing nanogenerators that operate by bending zinc oxide nanowires and nanobelts. The new components take advantage of the relationship between the mechanical and electronic coupled behavior of piezoelectric nanomaterials, a mechanism the researchers call "nano-piezotronics."

注: " Nano Piezotronics" 源于 "Mechatronics"相同的构词法。

"Mechatronics" is the synergistic combination of mechanical engineering ("mecha" for mechanisms, i.e., machines that 'move'), electronic engineering ("tronics" for electronics), and software engineering. [Wikipedia]

"Nano-piezotronics utilizes the coupling of piezoelectric and semiconducting properties to fabricate novel electronic components," said Zhong Lin Wang, a Regents Professor in the School of Materials Science and Engineering. "These devices could provide the fundamental building blocks that would allow us to create a new area of electronics."

For example, in a nano-piezotronic transistor, bending a one-dimensional zinc oxide nanostructure alters the distribution of electrical charges, providing control over the current flowing through it. By measuring changes in current flow through them, piezotronic sensors can detect forces in the nano- or even pico-Newton range. Other piezotronic sensors can determine blood pressure within the body by measuring the current flowing through the nanostructures. And, an electrical connection made to one side of a bent zinc oxide nanostructure creates a piezotronic diode that limits current flow to one direction

The nano-piezotronic mechanism takes advantage of the fundamental property of nanowires or nanobelts made from piezoelectric materials: bending the structures creates a charge separation - positive on one side and negative on the other. The connection between bending and charge creation has also been used to create nanogenerators that produce measurable electrical currents when an array of zinc oxide nanowires is bent and then released.

Development of a piezotronic gated diode based on zinc oxide nanowires was reported February 13 in the online advance issue of the journal Advanced Materials. Other nano-piezotronic components have been reported in the journals Nano Letters and Science. The research has been sponsored by the National Science Foundation (NSF), Defense Advanced Research Projects Agency (DARPA), the National Institutes of Health (NHI) and NASA.

"The future of nanotechnology research is in building integrated nanosystems from individual components," said Wang. "Piezotronic components based on zinc oxide nanowires and nanobelts have several important advantages that will help make such integrated nanosystems possible."

These advantages include:

1. Zinc oxide nanostructures can tolerate large amounts of deformation without damage, allowing their use in flexible electronics such folding power sources.
2. The large amount or deformation permits a large volume density of power output.
3. Zinc oxide materials are biocompatible, allowing their use in the body without toxic effects.
4. The flexible polymer substrate used in nanogenerators would allow implanted devices to conform to internal structures in the body.
5. Nanogenerators based on the structures could directly produce power for use in implantable systems.

优点: 大变形 大能量输出 生物兼容性 可移植 纳米发动机
In comparison to conventional electronic components, the nano-piezotronic devices operate much differently and exhibit unique characteristics. In conventional field-effect transistors, for instance, an electrical potential - called the gate voltage - is applied to create an electrical field that controls the flow of current between the device's source and its drain. In the piezotronic transistors developed by Wang and his research team, the current flow is controlled by changing the conductance of the nanostructure by bending it between the source and drain electrodes. The bending produces a "gate" potential across the nanowire, and the resulting conductance is directly related to the degree of bending applied.

"The effect is to reduce the width of the channel to carry the current, so you can have a 10-fold difference in the conductivity before and after the bending," Wang explained.

Diodes, which restrict the flow of current to one direction, have also been created through nano-piezotronic mechanisms to take advantage of a potential barrier created at the interface between the electrode and the tensile (stretched) side of the nanowire by mechanical bending. The potential barrier created by the piezoelectric effect limits the follow of current to one direction.

Nanogenerators, which were announced in the April 14, 2006 issue of the journal Science, harvest energy from the environment around them, converting mechanical energy from body movement, muscle stretching, fluid flow or other sources into electricity. By producing current from the bending and releasing of zinc oxide nanowires, these devices could eliminate the need for batteries or other bulky sources for powering nanometer-scale systems.

Piezotronic nanosensors can measure nano-Newton (10 -9) forces by examining the shape of the structure under pressure. Implantable sensors based on the principle could continuously measure blood pressure inside the body and relay the information wirelessly to an external device similar to a watch, Wang said. The device could be powered by a nanogenerator harvesting energy from blood flow.

Other nanosensors can detect very low levels of specific compounds by measuring the current change created when molecules of the target are adsorbed to the nanostructure's surface. "Utilizing this kind of device, you could potentially sense a single molecule because the surface area-to-volume ratio is so high," Wang said.

穷人富人的差异

1.自我认知穷人：很少想到如何去赚钱和如何才能赚到钱，认为自己一辈子就该这样，不相信会有什么改变。富人：骨子里就深信自己生下来不是要做穷人，而是要做富人，他有强烈的赚钱意识，这已是他血液里的东西，他会想尽一切办法使自己致富。

2.休闲穷人：在家看电视，为肥皂剧的剧情感动得痛哭流涕，还要仿照电视里的时尚打扮自己。富人：在外跑市场，即使打高尔夫球也不忘带着项目合同。

3. 交际圈子穷人：喜欢走穷亲戚，穷人的圈子大多是穷人，也排斥与富人交往，久而久之，心态成了穷人的心态，思维成了穷人的思维，做出来的事也就是穷人的模 式。大家每天谈论着打折商品，交流着节约技巧，虽然有利于训练生存能力，但你的眼界也就渐渐囿于这样的琐事，而将雄心壮志消磨掉了。富人：最喜欢交那种对 自己有帮助，能提升自己各种能力的朋友。不纯粹放任自己仅以个人喜好交朋友。

4.学习穷人：学手艺。富人：学管理。

5. 时间穷人：一个享受充裕时间的人不可能挣大钱，要想悠闲轻松就会失去更多挣钱的机会。穷人的时间不值钱的，有时甚至多余，不知道怎么打发，怎么混起来才不 烦。如果你可以因为买一斤白菜多花了一毛钱而气恼不已，却不为虚度一天而心痛，这就是典型的穷人思维。富人：一个人无论以何种方式挣钱，也无论钱挣得是多 是少，都必须经过时间的积淀。富人的玩也是一种工作方式，是有目的的。富人的闲，闲在身体，修身养性，以利再战，脑袋一刻也没有闲着；穷人的闲，闲在思 想，他手脚都在忙，忙着去麻将桌上多摸几把。

6. 归属感穷人：是颗螺丝钉。穷人因为自身的卑微，缺少安全感，就迫切地希望自己从属并依赖于一个团体。于是他们以这个团体的标准为自己的标准，让自己的一切 合乎规范，为团体的利益而工作，奔波，甚至迁徙。对于穷人来说，在一个著名的企业里稳定地工作几十年，由实习生一直干到高级主管，那简直是美妙得不能再美 妙的理想了。富人：那些团体的领导者通常都是富人，他们总是一方面向穷人灌输：团结就是力量，如果你不从属于自己这个团体，你就什么都不是，一文不名。但 另一方面，他们却从来没有停止过招兵买马，培养新人，以便随时可以把你替换。

7. 投资及对待财富穷人：经典观点就是少用就等于多赚。比如开一家面馆，收益率是100%，投入2万，一年就净赚2万，对穷人来说很不错了。穷人即使有钱，也 舍不得拿出来，即使终于下定决心投资，也不愿冒风险，最终还是走不出那一步。穷人最津津乐道的就是鸡生蛋，蛋生鸡，一本万利……但是建筑在一只母鸡身上的 希望，毕竟是那样脆弱。富人：富人的出发点是万本万利。同样的开面馆，富人们会想，一家面馆承载的资本只有2万，如果有1亿资金，岂不是要开5000家面 馆？要一个一个管理好，大老板得操多少心，累白多少根头发呀？还不如投资宾馆，一个宾馆就足以消化全部的资本，哪怕收益率只有20%，一年下来也有 2000万利润啊

周文重被任命为中国驻美国大使

外交部发言人刘建超24日在例行记者会上说，周文重已经被任命为中国驻美国大使，不久将去美国赴任。此前，国务院已任命前驻美大使杨洁篪为外交部副部长，免去周文重的外交部副部长职务。

周文重，江苏省人，大学毕业。1970年至1973年任中华人民共和 国北京外交人员服务局科员。1973年至1975年在大不列颠及北爱尔兰联合王国巴斯大学、伦敦经济学院进修。1975年至1978年任外交部翻译室科 员。1978年至1983年任驻美利坚合众国大使馆随员、三秘。1983年至1987年任外交部翻译室二秘、副处长、处长。1987至1990年任驻旧金 山总领馆副总领事。1990年至1993年任驻巴巴多斯特命全权大使兼驻安提瓜和巴布达特命全权大使。1993年至1994年任外交部美大司副司长。1994年至1995年任驻洛杉矶总领事（大使衔）。1995年至1998年任驻美利坚合众国大使馆公使。1998年至2001年任驻澳大利亚联邦特命全 权大使。2001年至2003年任外交部长助理。2003年5月被任命为外交部副部长

由＂王丹：我为什么希望到香港教书＂想到的

很小的时候，在电视上看到89天安门事件，后来学校的礼堂里贴了很多在这次事件中牺牲的解放军战士，再后来高三上政治课时， 听一个思想偏激的老师提过89学潮，直到再上次一个朋友提到，已经18年了。虽然自己没有赶上那个年代，没有亲身体验经历过，说法很多：89事件当事人，香港媒体，台湾媒体，海外媒体，和我们官方媒体，但是再过一百年，我也同意：

“ 上个世纪80年代末、90年代初，在中国发生了一场严重的政治风波，苏联解体，东欧剧变，在这个关系党和国家命运的严重的时刻，党中央紧紧依靠全党同志和全国人民，坚持十一届三中全会以来的路线不动摇，成功地稳住了中国改革开放的大局，捍卫了中国特色的社会主义事业。”

仔细看看，20个六四事件的录像和赵紫阳的讲话，我真的想问你们：王丹、封从德、柴玲、吾尔开希，你们到底想怎么样？你们都干了什么？18年过去了，你们还是没有恢复理智？你们有什么资格对政府说三道四？ 柴玲，这个女人，曾经在录像[1]里面说：“中国，你这样一个国家，太令我伤心了，虽然我们不能骂自己的祖国，但是我真的不愿为你奋斗” ，这个女人，过现在波士顿经验IT企业，曾经还夸口“希望能挣足够多的钱，买下中国，再把她建设成一个富强，民主的共和国”！

白痴女人，我想告诉你：你滚远点，祖国没有你，是万幸的！


Reference：

[1]天安门六四事件录像

[2]赵紫阳於凌晨4時50分前往天安门广场的谈话：

同学们，我们来得太晚了。对不起同学们了。你们说我们、批评我们，都是应该的。我这次来不是请你们原谅。我想说的是，现在同学们身体已经非常虚弱， 绝食已经到了第七天，不能再这样下去了。绝食时间长了，对身体会造成难以弥补的损害，这是有生命危险的。现在最重要的是，希望尽快结束这次绝食。我知道， 你们绝食是希望党和政府对你们所提出的问题给以最满意的答复。我觉得，我们的对话渠道是畅通的，有些问题需要一个过程才能解决。比如你们提到的性质、责任 问题，我觉得这些问题终究可以得到解决，终究可以取得一致的看法。但是，你们也应该知道，情况是很复杂的，需要有一个过程。你们不能在绝食已进入第七天的 情况下，还坚持一定要得到满意答复才停止绝食。

你们还年轻，来日方长，你们应该健康地活着，看到我们中国实现四化的那一天。你们不像我们，我们已经老了，无所谓了。国家和你们的父母培养你们上大 学不容易呀！现在十几、二十几岁，就这样把生命牺牲掉哇，同学们能不能稍微理智地想一想。现在的情况已经非常严重，你们都知道，党和国家非常着急，整个社 会都忧心如焚。另外，北京是首都，各方面情况一天天严重，这种情况不能再继续下去了，同学们都是好意，为了我们国家好，但是这种情况发展下去，失去控制， 会造成各方面的严重影响。

总之，我就是这么一个心意。如果你们停止绝食，政府不会因此把对话的门关起来，绝不会！你们所提的问题，我们可以继续讨论。慢是慢了一些，但一些问 题的认识正在逐步接近。我今天主要是看望一下同学们，同时说一说我们的心情，希望同学们冷静地想一想这个问题。这件事情在不理智的情况下，是很难想清楚 的。大家都这么一股劲，年轻人么，我们都是从年轻人过来的，我们也游过行，卧过轨，当时根本不想以后怎么样。最后，我再次恳请同学们冷静地想一想今后的 事。有很多事情总是可以解决的。希望你们早些结束绝食，谢谢同学们。

[3]王丹：我为什么希望到香港教书
六四已经过去将近18年了.这18年来,陆续有很多的知识分子和民运 人士被迫离开自己的国家,告别自己的家人,走上流亡的道路.这18年来,可以说,大家没有一天不盼望着可以回去自己的国家,与自己的家人朋友团聚的.我当 然也不例外.尤其是在春节这样的中国的传统节日,当然更希望能够跟家人一起吃团圆饭. 这样的全家团聚在别人的是理所当然的事情,可是在我,已经将近十几年没有过了.

在 将近8年的美国读书生涯之后,今年6月我预计将要毕业,即将面临人生的另一个阶段---就业.作为一个博士生,最主要的就业选择就是教书.如果我可以选 择,我会希望到香港去寻找教职.这首先我本人对香港一直有特殊的感情.这不仅是因为六四的时候,香港人将自己的命运与我们的命运连接在一起,我们当时可以 说是共患难;也是因为18年来,只有香港,坚持每年举办大型六四纪念活动,成为漫漫长夜中的一盏明灯.我一直很希望能够对香港人的热心有所回报.

其 实,希望到香港工作,另外很大的一个原因,也是因为香港离中国大陆很近,在”自由行”之后,家人探视会更加方便.我父母今年都已经是70高龄.尽管他们可 以去美国看望我.但是自古都是黑发人看白发人,哪有白发人看黑发人的道理呢?况且中国到美国路程遥远,对于年长者来说是越来越难以承受的负担.所以他们看 望我的机会会越来越少.我当然希望能够离他们近一些.尤其是我母亲因为心脏病的问题,身体状况并不是很好,作为子女,当然更希望能够在她身边照顾.

我 想只要是人,谁没有父母呢?今天我希望来香港,很大程度上是作为一个子女出于亲情的愿望.我可以理解中共政府,也许包括香港政府对于我的政治立场的反对. 但是中国毕竟有一个讲究基本的人情的文化传统,这种基本的伦理我很想看看当局是不是因为政治立场而放弃.今天,曾经与中共有血海深仇的国民党,它的主席都 可以访问大陆,当年那些杀了无数中共党员的国民党老将军都可以回去探视,我实在不理解,为什么当年要求推动民主的和平示威者,今天已经18年过去了,却无 论如何不允许回到大陆呢?今天,如果中共连一介书生都害怕,他的统治是否真的稳定,恐怕就要打上一个很大的问号了?

Nanotube remote-controlled actuators boost microelectromechanical systems (MEMS) applications

21 February 2007

In a recent article published in Nanotechnology, Shaoxin Lu and Balaji Panchapakesan, Department of Electrical and Computer Engineering, University of Delaware, US, reported on the construction of carbon-nanotube-based micro-optomechanical systems(CNT-MOMS) that could impact MEMS applications. While most MEMS devices use electrical energy to cause actuation, devices based on nanotubes can be powered optically with superior performance and low power compared to their electrostatic MEMS counterparts. The researchers have developed a CMOS-compatible process based on thin carbon nanotube film transfer, patterning and plasma etching, which properly integrates carbon nanotube ensembles in the MEMS devices. A micromechanical gripper has been demonstrated as an example of the concept CNT-MOMS. Displacement of ∼24 μm was obtained from a gripper of 430 μm in length, comparable to that of electrical-driven counterparts, but only at a low optical power cost of ∼240 μW. These CNT-MOMS can be implemented to design smart systems with multiple functionalities while powered remotely by light. It could have applications in adaptive optics, remote manipulation, and robotics for space and sensor applications. Panchapakesan believes that nanotube MOMS could impact future MEMS and nano-applications as they offer out-of-plane actuation, batch fabrication, scalability, remote-controllability, low power requirement and low cost compared to their MEMS electrical counterparts.