迷你磁场传感器：检测心跳的新手段

　　miniature magnetic sensor using a tiny cloud of atoms has successfully tracked a human heartbeat for the first time.
　　一种采用“微小原子云”技术的迷你磁场传感器，第一次成功地跟踪到了人类的心跳。

　　In a new study, researchers from the National Institute of Standards and Technology (NIST) and the German national metrology institute tried out the sensors – which until now have been operated mostly in physics laboratories – in a near-clinical setting.
　　来自美国国家标准与技术研究院(NIST)和德国国家计量研究所的研究人员，在一项新研究中试验了这种传感器。尽管直到目前为止，大部分研究尚处于物理实验室阶段，但研究人员一直将临床应用作为目标。

　　The new experiments were carried out at the Physikalisch Technische Bundesanstalt (PTB) in Berlin, Germany, in a building described as having the world"s best magnetic shielding – necessary to block the Earth"s magnetic field and other external sources from interfering with the high-precision measurements.
　　这项新的实验是在位于德国柏林的联邦物理技术研究院(PTB)的一座大楼里进行的。报道称，这座大楼具有全世界最好的磁屏蔽效果。这项实验要求隔离地磁和其它外部场源，因为它们会对高精度的测量产生干扰。

　　The NIST sensor – a tiny container of about 100 billion rubidium atoms in gas form, a low-power infrared laser, and optics – measured the heart"s magnetic signature in picoteslas (trillionths of a tesla). The tesla is the unit that defines magnetic field strength.
　　NIST的传感器是一个装有约1000亿气态铷原子的小型容器，其内部还带有一个低功率红外激光器和光学器件，可测量低至皮特斯拉的心脏磁场信号。（即一万亿分之一特斯拉，特斯拉是磁感应强度的计量单位。）

　　For comparison, the Earth"s magnetic field is a million times stronger (measured in millionths of a tesla) than a heartbeat, and an MRI machine uses fields several million times stronger still (operating at several tesla).
　　相比心跳，地磁场要强一百万倍（在百万分之一特斯拉数量级），磁共振成像机在静止时的磁场就要强几百万倍（而在工作时，可以强到几个特斯拉）

　　In the experiments at PTB, the NIST sensor was placed 0.20 inches (five millimeters) above the left chest of a person lying face up on a bed. The sensor successfully detected the weak but regular magnetic pattern of the heartbeat.
　　在PTB进行的实验中，受试者趴在床上，NIST传感器置于左胸以上0.2英寸（5毫米）。传感器成功探测到心跳所伴随的微弱而规则的磁场变化。

　　The same signals were recorded using the "gold standard" for magnetic measurements, a SQUID (superconducting quantum interference device). A comparison of the signals confirmed that the NIST mini-sensor correctly measured the heartbeat and identified many typical signal features.
　　研究者同时利用磁场测量的“金标准”——超导量子干涉器件(SQUID)对心跳信号进行了记录。两种传感器记录的比较，证实NIST的迷你传感器确实探测到了心跳，并获得了许多典型的信号特征。

　　The NIST mini-sensor generates more "noise" (interference) in the signal but has the advantage of operating at room temperature, whereas SQUIDs work best at –452 degrees Fahrenheit (-269 degrees Celsius) and require more complicated and expensive supporting apparatus.
　　NIST的迷你传感器在信号中产生了较多的“噪声”（干扰），但具有室温工作的优点。而SQUID要在摄氏-269底（华氏-452度）才能进入最佳状态，并且需要更加复杂和昂贵的支持装置。

　　A spin-off of NIST"s miniature atomic clocks, NIST"s magnetic mini-sensors were first developed in 2004. Recently, they were packaged with fiber optics for detecting the light signals that register magnetic field strength.
　　作为NIST小型原子钟的副产品，NIST的这种迷你传感器最早研发于2004年。目前，它们被封装进检测光信号的光学器件，以记录磁场的强度。

　　In addition, the control system has been reduced in size, so the entire apparatus can be transported easily to other laboratories.
　　此外，控制系统的体积更小，这样整个装置到能方便地运送到其它实验室。

　The new results, described in the journal Applied Physics Letters, suggest that NIST mini-sensors could be used to make magnetocardiograms, a supplement or alternative to electrocardiograms.
　　应用物理杂志的介绍的这一新结果，意味着NIST的迷你传感器可以用来进行磁场测量，这种测量可补充或替代心电图。

　Further tests of the NIST atom-based magnetic sensors at PTB are planned and could confirm the potential for more biomedical applications.
　　目前NIST正计划继续在PTB对这种原子磁场传感器进行进一步测试，以确认其在医学领域的应用潜力。

　　相关产品：CM-01

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