You are more transparent than you think - Sajan Saini

翻译人员: Han Zheng 校对人员: Carol Wang

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,

护士测量我们的身高、体重、血压，

and attaches a glowing plastic clip to our finger.

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?

这是如何办到的？

How can a plastic clip learn something about our blood…

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？

without a blood sample?

Here’s the trick:

奥秘就在于：

our bodies are translucent,

我们的身体是半透明的，

meaning they don’t completely block and reflect light.

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,

相反，一部分光线可以 透过皮肤、肌肉和血管

muscles, and blood vessels.

穿透我们的身体。

Don’t believe it?

不相信，是吗？

Hold a flashlight to your thumb.

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—

想想那个称为脉搏血氧仪 的医用手指夹的工作原理。

it’s called a pulse oximeter.

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,

它是通过手指夹一侧的 红色微型 LED 灯

and a small light detector on the other.

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

血管中的还原血红蛋白

比氧合血红蛋白吸收更多红光。

more strongly than its oxygenated counterpart.

So the amount of light that makes it out the other side

因此能够穿透手指的光的数量

depends on the concentration ratio of the two types of hemoglobin.

取决于两种血红蛋白的吸光比例。

但是任意两个病人手指的 血管大小都不尽相同，

But any two patients will have different-sized blood vessels in their fingers.

For one patient, a saturation reading of ninety-five percent

95% 的饱和指数对某个病人来说

corresponds to a healthy oxygen level,

是一个健康的含氧水平。

but for another with smaller arteries,

但对动脉小的病人来说，

the same reading could dangerously misrepresent the actual oxygen level.

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,

光由许多不同波长的光线组成光谱，

and infrared light lies just beyond the visible colors.

红外线光在可见光之外。

All molecules, including hemoglobin,

所有分子，包括血红蛋白，

absorb light at different efficiencies across this spectrum.

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

所以对比从红色光 和红外线光的吸收程度，

provides a chemical fingerprint to eliminate the blood vessel size effect.

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

如今，一个新兴的医学 传感器产业正在

通过大小不超过 0.1 毫米的 微型光操纵设备，

of precision chemical fingerprinting,

using tiny light-manipulating devices no larger than a tenth of a millimeter.

探索前所未有的高精度 化学指纹提取术。

This microscopic technology,

这一微观技术，

called integrated photonics,

又称集成光子学，

is made from wires of silicon that guide light—

由能导光的硅线制成——

就像水管中的水一样——

like water in a pipe—

to redirect, reshape, even temporarily trap it.

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,

环形谐振器设备由一个 环状硅线构成，

is a light trapper that enhances chemical fingerprinting.

用来阻滞光束以提高 化学指纹精度。

When placed close to a silicon wire,

当该装置靠近硅线时，

a ring siphons off and temporarily stores only certain waves of light—

它会吸收并暂时储存一些 特定的光波——

即光波波长的整数倍

those whose periodic wavelength fits a whole number of times

along the ring’s circumference.

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,

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。

to give a fundamental note and its overtones.

Ring resonators were originally designed

环形谐振器最初的设计

to efficiently route different wavelengths of light—

是应用在光纤通信网中，

each a channel of digital data—

用于有效分路不同波长的光波——

in fiber optics communication networks.

每个光波对应一个电子数据通道。

But some day this kind of data traffic routing

但未来这种数据分流设备

may be adapted for miniature chemical fingerprinting labs,

也许会用于微型化学指纹检验室，

on chips the size of a penny.

用在只有 1 分硬币大小的芯片上。

These future labs-on-a-chip may easily, rapidly,

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。

and non-invasively detect a host of illnesses,

医生可以在办公室里 检验我们的唾液和汗液，

by analyzing human saliva or sweat in a doctor’s office

or the convenience of our homes.

有条件者也可以在家检验。

Human saliva in particular

人的唾液尤其能够

mirrors the composition of our bodies’ proteins and hormones,

反映人体的蛋白和激素构成，

and can give early-warning signals for certain cancers

并能够发出对某些癌症、感染、

and infectious and autoimmune diseases.

以及自体免疫疾病的早期预警。

To accurately identify an illness,

为了精准诊断一种疾病，

labs-on-a-chip may rely on several methods,

芯片检验室会采用

包括化学指纹采集在内的几种方法，

including chemical fingerprinting,

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—

唾液中不同的生物分子 吸收同一波长的光，

but each has a distinct chemical fingerprint.

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

每个微调过的小环

may each siphon off a slightly different wavelength of light

都会吸入稍有不同的光波，

and send it to a partner light detector.

并发给配对的测光仪。

Together, this bank of detectors will resolve

最终，这组测光仪将解析

the cumulative chemical fingerprint of the sample.

样本中所有的化学指纹集合。

From this information, a tiny on-chip computer,

由这些信息，装载着 不同分子化学指纹库的

containing a library of chemical fingerprints for different molecules,

微型芯片电脑

may figure out their relative concentrations,

就能算出它们的相对浓度，

and help diagnose a specific illness.

以帮助诊断特定疾病。

From globe-trotting communications to labs-on-a-chip,

从全球通讯到芯片检验室，

humankind has repurposed light to both carry and extract information.

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。