Materials scientists have created a small, wearable sensor that can read the molecular composition of sweat and send its results

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问题    Materials scientists have created a small, wearable sensor that can read the molecular composition of sweat and send its results in real time to a smartphone. 【F1】The flexible plastic patches—which can be incorporated into wristbands and headbands—may be able to provide early warning of changes in the body, say their creators.
   【F2】"The idea is to have this thumbs-up or thumbs-down device that will give real-time information: it could provide an alarm that you need to take some medication, or that you’re getting dewatered and need to drink some water," says Ali Javey, at the University of California, Berkeley, who helped to develop the sensors. He and his colleagues report their work in Nature.
   Several labs have been developing sensors for sweat, which contains a multitude of electrolytes and metabolites—the final products of the body’s biological processes (for example, the lactic acid that builds up after exercise). But these sensors have tended to measure only one component of sweat at a time, and generally cannot transmit their measurements in real-time. 【F3】When the sensors come into contact with sweat they generate electrical signals that are amplified and filtered, and then recorded using skin temperature. This step is essential, says Javey. "Electrochemical sensors are very sensitive to temperature, and skin temperature can vary quite a bit when we are sweating." The data are then wirelessly transmitted to a smartphone.
   It’s an impressive achievement, says Jason Heikenfeld at the University of Cincinnati in Ohio, whose lab has also been developing wearable sweat sensors. "The sensors typically require electronics that are normally the size of a shoebox; they miniaturized them into something that can wrap around your wrist," he says. 【F4】The sensors have to be fabricated from basic chemicals in the laboratory, and cannot be purchased off the shelf like sensors found in today’s wearables, which measure heart rate and detect the body’s motion.
   Sweat sensors will never be as accurate as blood tests, which are the "gold standard", says Javey. 【F5】Our bodies closely control the molecular composition of our blood, but the content of our sweat is more variable and is sometimes influenced by germs on our skin—so the medical relevance of the information that sweat provides will need to be rigorously tested. However, sweat does have an advantage: taking blood samples with a needle is not a practical means of assessing health on a minute-by-minute basis.
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答案这种传感器必须得在实验室里从最基本的化学品开始制造,它不像今天能买到现成测心率和检测人体移动的可穿戴传感器一样。

解析 ①本句为并列复合句。分句1为主谓结构,分句2末尾包含了一个which引导的非限定性定语从句。②and后的分句2主语仍然是The sensors。off the shelf意为“现成的”。found in today’s wearables作后置定语修饰先行词sensors,说明“这是今天可见到的可穿戴传感器”。③which引导的定语从句修饰的先行词是前一句中的sensors,说明这个传感器的特点:测心率和检测人体移动。
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