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It's an increasingly common sight in hospitals around the world:
在全球的医院中，这一现象越来越普遍：
a nurse measures our height, weight, blood pressure, and attaches a glowing plastic clip to our finger.
护士测量我们的身高、体重、血压，并用一个闪光塑料夹夹住我们的手指。
Suddenly, a digital screen reads out the oxygen level in our bloodstream.
电子频幕立刻就显示出我们血液中的氧气水平。
How did that happen? How can a plastic clip learn something about our blood... without a blood sample?
这是如何办到的？在不采血样的情况下，塑料夹是如何测出血液的相关信息呢？
Here's the trick: our bodies are translucent, meaning they don't completely block and reflect light.
奥秘就在于：我们的身体是半透明的，也就是说，我们的身体不会完全阻挡并反射光线。
Rather, they allow some light to actually pass through our skin, muscles, and blood vessels.
相反，一部分光线可以透过皮肤、肌肉和血管穿透我们的身体。
Don't believe it? Hold a flashlight to your thumb.
不相信，是吗？用手电筒照射你的大拇指试试。
Light, it turns out, can help probe the insides of our bodies.
你会发现，光线可以穿透到我们的身体里。
Consider that medical fingerclip -- it's called a pulse oximeter.
想想那个称为脉搏血氧仪的医用手指夹的工作原理。
When you inhale, your lungs transfer oxygen into hemoglobin molecules,
当你吸气时，肺将氧气输送给血红蛋白分子，
and the pulse oximeter measures the ratio of oxygenated to oxygen-free hemoglobin.
脉搏血氧仪能测量氧合血红蛋白与还原血红蛋白的比率。
It does this by using a tiny red LED light on one side of the fingerclip, and a small light detector on the other.
它是通过手指夹一侧的红色微型LED灯和另一侧的小光探测器实现的。
When the LED shines into your finger,
当LED灯光射进你的手指时，
oxygen-free hemoglobin in your blood vessels absorbs the red light more strongly than its oxygenated counterpart.
血管中的还原血红蛋白比氧合血红蛋白吸收更多红光。
So the amount of light that makes it out the other side depends on the concentration ratio of the two types of hemoglobin.
因此能够穿透手指的光的数量取决于两种血红蛋白的吸光比例。
But any two patients will have different-sized blood vessels in their fingers.
但是任意两个病人手指的血管大小都不尽相同。
For one patient, a saturation reading of ninety-five percent corresponds to a healthy oxygen level,
95%的饱和指数对某个病人来说是一个健康的含氧水平，
but for another with smaller arteries, the same reading could dangerously misrepresent the actual oxygen level.
但对动脉小的病人来说，同样的指数可能会危险地曲解真实含氧水平。
This can be accounted for with a second infrared wavelength LED.
这一现象可用第二个红外波长的LED来弥补。
Light comes in a vast spectrum of wavelengths, and infrared light lies just beyond the visible colors.
光由许多不同波长的光线组成光谱，红外线光在可见光之外。
All molecules, including hemoglobin, absorb light at different efficiencies across this spectrum.
所有分子，包括血红蛋白，对光谱中不同光线的吸收程度不尽相同。
So contrasting the absorbance of red to infrared light provides a chemical fingerprint to eliminate the blood vessel size effect.
所以对比从红色光和红外线光的吸收程度，可得到化学指纹，用来排除血管大小差异带来的影响。
Today, an emerging medical sensor industry is exploring all-new degrees of precision chemical fingerprinting,
如今，一个新兴的医学传感器产业正在探索前所未有的高精度化学指纹提取术，
using tiny light-manipulating devices no larger than a tenth of a millimeter.
通过大小不超过0.1毫米的微型光操纵设备。
This microscopic technology, called integrated photonics,
这一微观技术，又称集成光子学，
is made from wires of silicon that guide light -- like water in a pipe -- to redirect, reshape, even temporarily trap it.
由能导光的硅线制成--就像水管中的水一样--能改变方向、改变形状，甚至会暂时阻滞光束。
A ring resonator device, which is a circular wire of silicon, is a light trapper that enhances chemical fingerprinting.
环形谐振器设备由一个环状硅线构成，用来阻滞光束以提高化学指纹精度。
When placed close to a silicon wire, a ring siphons off and temporarily stores only certain waves of light
当该装置靠近硅线时，它会吸收并暂时储存一些特定的光波，
those whose periodic wavelength fits a whole number of times along the ring's circumference.
即光波波长的整数倍等于环周长的周期性光波。
It's the same effect at work when we pluck guitar strings.
这和我们拨动吉他弦的原理相似。
Only certain vibrating patterns dominate a string of a particular length, to give a fundamental note and its overtones.
一根琴弦在特定长度时才会产生某种震动模式，才能产生主音和泛音。
Ring resonators were originally designed to efficiently route different wavelengths of light
环形谐振器最初的设计是用于有效分路不同波长的光波，
each a channel of digital data -- in fiber optics communication networks.
每个光波对应一个电子数据通道，应用在光纤通信网中。
But some day this kind of data traffic routing may be adapted for miniature chemical fingerprinting labs, on chips the size of a penny.
但未来这种数据分流设备也许会用于微型化学指纹检验室，用在只有1分硬币大小的芯片上。
These future labs-on-a-chip may easily, rapidly, and non-invasively detect a host of illnesses,
未来这些芯片检验室能够实现对各类疾病的轻松、迅速、无创之检测，
by analyzing human saliva or sweat in a doctor's office or the convenience of our homes.
医生可以在办公室里检验我们的唾液和汗液，有条件者也可以在家检验。
Human saliva in particular mirrors the composition of our bodies' proteins and hormones,
人的唾液尤其能够反映人体的蛋白和激素构成，
and can give early-warning signals for certain cancers and infectious and autoimmune diseases.
并能够发出对某些癌症、感染、以及自体免疫疾病的早期预警。
To accurately identify an illness, labs-on-a-chip may rely on several methods, including chemical fingerprinting,
为了精准诊断一种疾病，芯片检验室会采用包括化学指纹采集在内的几种方法，
to sift through the large mix of trace substances in a sample of spit.
对唾液样本中大量的混杂微量物质进行筛选。
Various biomolecules in saliva absorb light at the same wavelength -- but each has a distinct chemical fingerprint.
唾液中不同的生物分子吸收同一波长的光，但每个分子都有独一无二的化学指纹。
In a lab-on-a-chip, after the light passes through a saliva sample,
在芯片检验室中，当光透过唾液样本之后，
a host of fine-tuned rings may each siphon off a slightly different wavelength of light and send it to a partner light detector.
每个微调过的小环都会吸入稍有不同的光波，并发给配对的测光仪。
Together, this bank of detectors will resolve the cumulative chemical fingerprint of the sample.
最终，这组测光仪将解析样本中所有的化学指纹集合。
From this information, a tiny on-chip computer, containing a library of chemical fingerprints for different molecules,
由这些信息，装载着不同分子化学指纹库的微型芯片电脑
may figure out their relative concentrations, and help diagnose a specific illness.
就能算出它们的相对浓度，以帮助诊断特定疾病。
From globe-trotting communications to labs-on-a-chip, humankind has repurposed light to both carry and extract information.
从全球通讯到芯片检验室，人类把光用于新用途，用于承载和提取信息。
Its ability to illuminate continues to astonish us with new discoveries.
光的照明能力正通过各种新发现令我们眼前一亮。
