Watching Microcurrents Flow[理工类职称英语教材]
We can now watch electricity as it flows through even the tiniest circuits.By scanning the magnetic field generated as electric currents flow through objects, physicists have managed 1 .The technology will allow manufacturers to scan microchips for faults,as well as revealing microscopic defects in anything from aircraft to banknotes.
Gang Xiao and Ben Schrag at Brown University in Providence,Rhode Island,visualize the current by measuring subtle changes in the magnetic field of an object and 2 .
Their sensor is adapted1 from an existing piece of technology that is used to measure large magnetic fields in computer hard drives.2 “We redesigned the magnetic sensor to make it capable of measuring very weak changes in magnetic fields,”says Xiao.
The resulting device is capable of detecting a current as weak as 10 microamperes,even when the wire is buried deep within a chip,and it shows up features as small as 40 nanometers across.
At present,engineers looking for defects in a chip have to peel off the layers and examine the circuits visually；this is one of the obstacles 3 . But the new magnetic microscope is sensitive enough to look inside chips and reveal faults such as short circuits,nicks in the wires or electro migration——where a dense area of current picks up surrounding atoms and moves them along.”It is like watching a river flow,”explains Xiao.
As well as scanning tiny circuits,the microscope can be used to reveal the internal structure of any object capable of conducting electricity.3For example,it could look directly at microscopic cracks in an aeroplane’s fuselage, 4 .The technique cannot yet pick up electrical activity in the human brain because the current there is too small,but Xiao doesn’t rule it out4 in the future.“I can never say never,”he says.
Although the researchers have only just made the technical details of the microscope public,it is already on sale,5from electronics company Micro Magnetics in Fall River,Massachusetts.It is currently the size of a refrigerator and takes several minutes to scan a circuit,but Xiao and Schrag are working 5 .
词汇：
circuit n.电路
scan/ vt.扫描；细看
magnetic adj.磁铁的；磁石的
visualize vt.使……形象化； 使……具体化
subtle adj.精巧的；细微的
dense adj.密集的；稠密的
sensor n.感应器
注释：
1.is adapted：(使)适应。作不及物动词时的用法是：“adapt to+名词性成分”,如：The young man from the countryside adapted well to life in the big city.这个农村青年很能适应大城市的生活。易混的词：(1)adopt采取；采纳(及物动词)。adopt a positive attitude采取积极的态度。(2)adept熟练的；擅长的(形容词)。be adept in(或at),如：This boy is adept in／at figures.这个男孩擅长计算。
2.computer hard drives：计算机硬盘
3.conducting electricity：导电
4.rule…out：排除……的可能性。又如：The police have ruled out murder in the case of the girl’s
