George Whitesides:邮票大小的实验室

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http://dotsub.com/view/5ca11e90-b90a-4cd3-a5cc-1bc26897c37f
George Whitesides:邮票大小的实验室
今天我想和大家一同探讨的问题是 具有现实意义的 即人们如何获得基本的医疗保障 我们都知道，现在是一个成本至上的社会 对于此我们应如何取舍？ 首先，我们来讨论这样一种情况 这个情况是这样的 如果我们想要治疗某种疾病 我们必须先弄清楚这是什么样的一种病 只有通过诊断，我们才能进行相应的治疗。
同样，诊断也是我们这个项目的核心问题 这里，称作诊断为先，或零成本诊断。 在座的各位或许会问 如何才能提供零成本的医疗信息？ 接下来，我就用两个例子予以说明。 其实，艰苦的随军医疗 与第三世界的医疗情况甚是相像 两者都面临，匮乏的医疗资源、艰苦的生存环境 及一系列因营养失衡、体重不足，而引起的问题。 同样，两者在普通医疗保健 和诊断方面也没有太大的区别。
其实，今天我们在探讨的这项新技术 是非常适合第三世界与发展中国家的。 当然，就我个人而言，我认为它还有更广泛的应用。 因为准确的疾病诊断信息对疾病的治疗是至关重要的。 来 我们来看看这两张图片 第一张图片是位于非洲的一家高级实验室 第二张则是一位企业家 他正一个集市里做着一些检验工作。 或许这并没有传达任何有关医疗的信息。 但同时这也说明他所作的并不是最有效的。
我们这一项目的目标是什么？ 其实我们最为关注的问题是 如何降低使用成本。 从美国市场的角度来看， 如果我们想要成功推广某一方案 我们就必须要试图去降低它的成本。 因为，无论这一方案是多么有效 市场也不可能把10万美元的仪器费用， 降至零。 这是不可能办到的。
所以，我们采用了另外的方法来出奇制胜。 有人问 “世界上什么材料最廉价且适用于制造诊断疾病的仪器， 同时能提供有用的信息， 而且能增添功能？“ 对这一问题，我们的答案是纸张。 现在大家看到的是，用纸做的诊断设备的模型 它的宽度约为1厘米 大小与我们的指甲差不多 纸上的线条来自于 一种聚合物（可与被测物质相互反应，随后产生一系列的物理、化学变化） 这是纸质的，而纸是有吸附功能的。 众所周知，纸啊，布料啊，可以吸收液体。 例如，我们不小心把酒洒在了桌布上，那么桌布会一片狼藉。 如果弄到了衬衣上，那么衬衣也被弄脏了。 这些现象都反应了纸张的亲水特性。
这也是我们仪器的运作原理。 我们在试片的底部，滴入一滴液体 在这个检测中，我们使用的是尿液 滴入的尿液集中在这个小槽中， 左边棕色部分显示尿液中葡萄糖的含量 右边蓝色部分则显示尿液中蛋白质的含量 随后将两部分的信息相结合， 我们便获得 初步所需的检测结果 这就是一个用简单的纸张制成的分析仪的例子
现在，我们来看看这类仪器是如何制成的？ 第一个问题，为什么选择纸质？ 图片中手指上 呈现的也是类似刚才介绍过的分析仪 选择用纸质的首要原因是“纸，无处不在” 我们可以用纸做成 餐巾纸，卫生纸等类似的许多其他纸类物品 还有用纸来包装，等等。
所以，产能上基本没有限制。 其次是 “小小一片纸能完成许许多多的测试” 待会，我会给大家讲解一堆纸张如何 可能被用来进行 10万个检验。
最后一个原因，大家往往比较容易忽略 因为在发达国家 我们不太使用针刺的方法来获取检验样本 针刺法就是用针，刺穿皮肤获得检验样本，而残余样本会滞留在针里。 如果我们抽取了某人的血液样本 而那个人可能携带丙肝病毒的血液样本 在检测后，样本是不可以随便遗弃的™ 这时，我们就会考虑， 怎样才能安全有效的清理这些医疗垃圾? 最为简单的方法就是焚烧 所以，纸质的检测仪确实是一种实用的方法 来采用
好了 现在 在座的各位都应该认同 纸是非常好用的一种材料，对。 这里的各位 粗粗看来，一半都是女性 相信大家，可能都经历过验孕测试。 大多数的验孕仪， 就像是左边图片中的那样 学术上，我们称之为横向流动免疫测定仪。 在这一检测中 我们让 可能含有HCG（绒毛膜促性腺激素，荷尔蒙的一种）的尿液 渗透一张试纸来进行检测 试纸上有两条线 一条是用来显示试纸是否起作用的，另一条是用来检测是否怀孕的。
这对于新时代而言，这是一项非常赞的发明。 有关怀孕更重要的是 你只能是怀孕了或是没有怀孕 你不可能是不完全的怀孕了，或是正想着而变怀孕了， 或者是其它一些中间状态。 对于上述的问题，验孕试纸能给我们很好的回答 但却无法给予更多的量化的信息
图片中的这些，同样也是试纸。 但，这里的尿样检测 却有了其他的意义 试纸上有许多的颜色， 在不同的情况下，显示不同的结果 在这种复杂的情况下，我们如何办到？ 所以我们采用的办法就是，问我们自己 如何实现纸质检测的构想？ 其实，这个问题只要用简单的工程方法即可解决 原材料我们只用到了纸张 然后使用一种叫做“蜡膜打印机”的新型打印机 这种打印机和普通的打印机，在外表几乎没有区别。 启动机器，加温蜡盒 蜡油便会渗透到纸张内 然后，你想要的测试纸就被打印出来了
这类打印机，现在的售价大概是每台800美元。 我估算了一下，如果开足马力，连续工作24小时。 那么，打印后的蜡纸可供一千万的试验用量 所以，这个测试纸的构想很好的实现了 这里我有一个具体的实例 这是由12张纸组成的，可供8次试验的试纸 仅用2秒钟制成 十分的迅速 这里还有一个非常重要的问题， 因为我们用的是彩色打印机 众所周知，彩色打印机可以打印出不同的颜色。 待会，我再说明这个的具体用处。
大家可能联想到的第二个问题是， 怎样分析、测算试验结果？ 解答前，我还要先澄清一个观点 一直以来，大家想要分析的东西。其实，与我们想要获得的信息是有出入的。 这类似于“发热确诊原因”的情形 当病人来到诊所时,他们感到发烧，感到不适 他们得了什么病呢？ 是肺结核？艾滋？ 还是普通感冒？ 这是个很复杂的问题 其他的可能性，在此不做深究 因为实在是有太多的可能性了 但这些病因 如艾滋、肝炎、疟疾 肺结核，等等 还有包括一些简单的因素，譬如疗程指导。
还个因素比我们想象的要更复杂。 我有一位朋友负责跨文化精神病学的研究。 他对于病人不按时吃药的问题 十分关注 特别是，例如氨苯砜（抗麻风病的一种药物） 及其他需要长期服用的药物 他告诉我，在印度某个村庄流传着一个非常有意思的故事。 某日，医生问：“你是否服用氨苯砜？”病人答：“是” 医生问：“你是每天服用么？”病人答：“是” 医生问：“你是否服用治疗了一个月？”病人答：“是” 大家知道么，其实，那个病人真正的意思是 他在早晨给自家的狗 喂了30天剂量的氨苯砜 ♫ 病人说了实话。 因为在不同的文化背景下， 狗是人类的替代物 对话中使用的，“今天”，“这个月”，“雨季前” 也会引发很多的歧义 这个故事 主要告诉我们 对于枯燥、乏味的沟通 我们更需要明确交流双方的信息详情
言归正传，我们来看一例典型的测试 首先，扎破无名指， 获得50微毫升的血液样本 这么多的血液就已经足够 因为，我们无需再使用常规的检测仪器。 你一般不能很方便的操纵这么少量的样本 但是，等一下我将具体演示我们是怎样办到的。 好了，你只要提供一滴血液样本 然后将血液擦拭在试纸仪器上 仪器过滤了血液中的细胞，唯独让血清得以通过 然后，你在试纸层上 观察到了许多的颜色 这些不用的颜色，显示了相应的疾病信息 但是，这些颜色分析起来有些复杂。 似乎，对你我而言，这些颜色看上去都挺正常的。 同样，（在仪器推广使用前）我们都没有过多的精力 进行一定的使用培训
那么 我们应如何处理需要定量分析的测试呢？ 我们和其他很多同行 都想到 当今有一种已非常的流行， 而且已变成能几乎解决所有问题的办法， 那就是手机。在我们的这个例子里，是有拍照功能的手机。 在印度，每月大概有600万的拍照手机用户。 所以，这个设想就很容易实现。 一张纸质分析仪 你涂抹上血样，等到出现检测的颜色。 然后，拍照上传到中央实验室。 你不必麻烦医生 你只要找个能采取这些信息的人 然后，在诊所里，一个医生，或一台智能的电脑 来分析采集到的信息。 这个办法的效果非常好， 特别是当彩色打印机已打印出彩色线条，这些有颜色的线条 能让测试过程一目了然。
因此，我认为未来的医护人员 并不一定是科班出生的医生 只要他年满18周岁，无其他全职工作。 在背包中有充足的试纸仪器； 一把柳叶刀，可用于突发的采血需要； 还有一把AK47 就能解决所有的工作需要和人生安全的问题。
这里还有个非常有趣的现象 那就是 人们如何通过错综复杂的电话系统 传递有用的信息并得到回馈？ 图片中的火星漫步者 已经成功的处理这一系列的问题 如果你没有足够的带宽来进行测量， 如何才能精确的分析在火星上的颜色呢？ 这个问题的答案并不难， 但我不想在这里再说一遍了， 我想用这个例子说明的是，用来解决这一问题的信息系统， 早已存在了。
还有一点，我需要指明的就是 手机的计算功能 不比你平时使用的台式机 差多少。 因为这是一个神奇的装置，它的巨大潜力才刚刚开启。 我不确定，“一台电脑，一个孩子“的构想是否可以引起下一场大变革， 但我手上拿的这个就像是未来的电脑， ”电脑屏幕“已经在那里了，而且也有众多的使用者
现在就让我来演示一下这些新仪器 首先 大家看到的是另一个厘米大小的分析仪。 不同的颜色由不同的染料着色而成 大家或许已经注意到 一个非常有趣的现象 似乎黄色的线条，在通过红色和蓝色的线段时， 有些消失部分消失了 这是怎么回事？我们是怎么让某种流体通过另一种流体的？ 答案是：“当然，没有” 我们只是让一种的流体从其他流体的下面或是上面通过而已
但现在问题是，你如果让一种流体 流过一张纸的上面或是下面呢？ 具体的答案与细节原因 并不复杂 为了让信息更加精确， 我们使用多张纸 每张纸都有其自己的流体系统， 然后，我们将其从纸上分开， 再用双面胶，将他们粘在一起。 这里用的双面胶就是我们日常用于地毯粘在地板上的那种。 这样一来，液体便可以从这层流到那层。 它们会沿着自己的轨道流动。 自我分流
你们在右下角看到的是 血液简单测试的样本 血液样本从最高处流入， 然后，自上而下从16个小孔中自我分流， 直到试纸的最后一层。 这个纸张分析仪，看起来有些像芯片， 大概有2张纸张的厚度 在这个例子中，我们只对 检测的可重复性感兴趣。 当然，这也是，帮助我们解决 “发热本因”的基本原理。 因为，这里的每一个点 可以用来测试 某一种疾病特定含有的一系列生物标记。 然后这种检测在适当的时候下就会发生作用。
图片中，是另一个相对复杂的检测仪。 这是一粒芯片 你在它的四个角上，沾上检验样本后，这些液体便会流向中央。 液体会自动分流， 通过不同的小井或小孔，然后发生颜色变化。 在这里， 我们只用到了纸张和地毯胶带。 因此，它的成本仍然非常的低。 所以，我们是可以大力推广这一仪器的。
最后，我还有些信息要与大家分享。 这样有便于构想得更好实现 第一是 我们必须先将血液细胞与血清分离 通常的做法是 先用针刺获得血样 然后，用离心机分离。 这样的做法总有些繁琐 但问题是，当我们没有电力， 没有离心机时，该怎么办呢？ 让我们仔细的想一想 事实上，大家看，答案就在这里。 我们可以找个打蛋机， 这东西到处都有。 然后，我们把里面的刀片去掉， 然后，你取一只管子， 把改装过的打蛋鸡贴在上面。然后我们把血输入管子，然后旋转 谁都可以坐着然后慢慢的搅， 慢慢的使血清分离。
最后，我们声称我们研究了打蛋器的物理 和可自我调正的试管，和其他一些类似的东西， 我们把这些写成稿子发给了一个杂志社 我们还很自豪的标榜文章的标题 “打蛋器式的血清分离仪” ♫ 我们把文章寄出去后，却收到拒绝发表的通知。 我打电话给编辑 问道：“怎么回事？这怎么可能？” 编辑带着巨大的藐视回答道： “我已经读了这篇报道。 但是我们不会发表的， 因为我们只会发表科学。” 这是一个非常重要的问题。 因为 作为一个社会 我们必须得想想什么是最重要的。 如果我们所做的仅仅是在一些物理期刊上发发文章 那么社会就会出现很大的问题。
这里 还有个关于分光光度计的例子 分光光度计是用来测量光度吸收率的一种仪器。 这一仪器使用的前提是， 你需要有一个以接近1000赫兹闪动的光源 和另一个用来检测频率在1000赫兹光波的光源。 然后你即使在白天也可以使用这个仪器 但是，它的功能和 造价 大概是10万美元的设备是几乎等同的 它的成本仅50美元。我们甚至可以把成本变成只有50分， 要是我们一心想办到的话。 可为什么没有人做呢？答案是 “在这样的资本世界中，我们这样做怎能获利？” 这的确是有意思的问题。
最后，我们来回顾一下。 今天所讨论的是一个工程问题。 我们也问到了什么是科学的统一思想？ 我们也决定我们应该想 这不仅仅是成本控制的问题， 还是简易性的问题。 简易性是一个简单的词。但是我们得仔细想想 简易性到底意味着什么。 我知道简易性，但却不知道它的深层含义。
我因为太感兴趣了，我集合了 一些不同的人群一同探讨 在与我沟通的一群人中 有位来自麻省理工学院的孩子 他非常的聪明 完全可以被视为纯正的天才 我们用了一天的时间来讨论什么是纯粹、简易。 我也想告诉大家我的 有关这一深刻的科学思想的见解。 ♫ 所以就这么说，大家姑且能从我的演讲中得到一些回报吧。
谢谢
非常感谢 ♫

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George Whitesides: A lab the size of a postage stamp
The problem that I want to talk with you about is really the problem of how does one supply healthcare in a world in which cost is everything. How do you do that? And the basic paradigm we want to suggest to you, I want to suggest to you is, one in which you say that in order to treat disease you have to first know what you're treating -- that's diagnostics -- and then you have to do something.

So, the program that we're involved in is something which we call diagnostics for all, or zero-cost diagnostics. How do you provide medically relevant information at as close as possible to zero cost? How do you do it? Let me just give you two examples. The rigors of military medicine are not so dissimilar from the third world, poor resources, a rigorous environment, a series of problems in light weight, and things of this kind. And also not so different from the home healthcare and diagnostic system world.

So, the technology that I want to talk about is for the third world, for the developing world, but it has, I think, much broader application, because information is so important in the healthcare system. So, you see two examples here. One is a lab that is actually a fairly high end laboratory in Africa. The second is basically an entrepreneur who is set up and doing who knows what in a table in a market. I don't know what kind of healthcare is delivered there. But it's not really what is probably most efficient.

What is our approach? And the way in which one typically approaches a problem of lowering cost, starting from the perspective of the United States, is to take our solution, and then to try to cut cost out of it. No matter how you do that you're not going to start with 100,000 dollar instrument and bring it down to no cost. It isn't going to work.

So, the approach that we took was the other way around. To ask, "What is the cheapest possible stuff that you could make a diagnostic system out of, and get useful information, add function?" And what we've chosen is paper. What you see here is a prototypic device. It's about a centimeter on the side. It's about the size of a fingernail. The lines around the edges are a polymer. It's made of paper, and paper of course wicks fluid. As you know, paper, cloth, drop wine on the table cloth, and the wine wicks all over everything. Put it on your shirt, it ruins the shirt. That's what a hydrophilic surface does.

So, in this device the idea is that you drip the bottom end of it in a drop of, in this case, urine. The fluid wicks its way into those chambers at the top. The brown color indicates the amount of glucose in the urine. The blue color indicates the amount of protein in the urine. And the combination of those two, is a first order shot at a number of useful things that you want. So, this is an example of a device made from a simple piece of paper.

Now, how simple can you make the production? Why do we choose paper? There is an example of the same thing, on a finger showing you basically what it looks like. One reason for using paper is that it's everywhere. We have made these kinds of devices using napkins and toilet paper and wraps, and all kinds of stuff.

So, the production capability is there. The second is, you can put lots and lots of tests in a very small place. I'll show you in a moment that the stack of paper there would probably hold something like 100,000 tests, something of that kind.

And then finally, a point that you don't think of so much in developed world medicine, it eliminates sharps. And what sharps means in needles, things that stick. If you've taken a sample of someone's blood and the someone might have hepatitis C, you don't want to make a mistake and stick it in you. It just, you don't want to do that. So, how do you dispose of that? It's a problem everywhere. And here you simply burn it. So, it's a sort of a practical approach to starting on things.

Now, you say, if paper is a good idea, other people have surely though of it. And the answer is, of course, yes. Those half of you, roughly, who are women, at some point may have had a pregnancy test. And the most common of these is in a device that looks like the thing on the left. It's something called a lateral flow immunoassay. And in that particular test urine, either containing a hormone called HCG does or does not flow across a piece of paper. And there are two bars. One bar indicates that the test is working. And if the second bar shows up, you're pregnant.

This is a terrific kind of test in a binary world. And the nice thing about pregnancy is either you are pregnant or you're not pregnant. You're not partially pregnant or thinking about being pregnant or something of that sort. So, it works very well there. But it doesn't work very well when you need more quantitative information.

There are also dipsticks. But if you look at the dipsticks, they're for another kind of urine analysis. There are an awful lot of colors and things like that. What do you actually do about that in a difficult circumstance? So, the approach that we started with, is to ask, is it really practical to make things of this sort? And that problem is now, in a purely engineering way, solved. And the procedure that we have is simply to start with paper. You run it through a new kind of printer called a wax printer. The wax printer does what looks like printing. It is printing. You put that on, you warm it a little bit. The wax prints through so it absorbs into the paper. And you end up with the device that you want.

The printers cost 800 bucks now. They'll make, we estimate that if you were to run them 24 hours a day they'd make about 10 million tests a year. So, it's a solved problem. That particular problem is solved. And there is an example of the kind of thing that you see. That's on a piece of 8 by 12 paper. That takes about two seconds to make. And so I regard that as done. There is a very important issue here, which is that because it's a printer, a color printer, it prints colors. That's what color printers do. I'll show you in a moment, that's actually quite useful.

Now, the next question that you would like to ask is what would you like to measure? What would you like to analyze? And the thing which you'd most like to analyze, we're a fair distance from. It's what's called "fever of undiagnosed origin." Someone comes into the clinic, they have a fever, they feel bad, what do they have? Do they have T.B.? Do they have AIDS? Do they have a common cold? The triage problem. That's a hard problem for reasons that I won't go through. There are an awful lot of things that you'd like to distinguish among. But then there are a series of things, AIDS, hepatitis, malaria, TB, others. And simpler ones such as guidance of treatment.

Now even that is more complicated than you think. A friend of mine works in trans-cultural psychiatry. And he is interested in the question of why people do and don't take their meds. So, Dapsone, or something like that, you have to take it for a while. There is a wonderful story of talking to a villager in India. And saying, "Have you taken your Dapsone?" "Yes." "Have you taken it every day?" "Yes." "Have you taken if for a month?" "Yes." What the guy actually meant was that he'd fed a 30 day dose of Dapsone to his dog, that morning. (Laughter) He was telling the truth. Because in a different culture, the dog is a surrogate for you, you know, "today," "this month," "since the rainy season," there are lots of opportunities for misunderstanding. And so an issue here is to in some cases to figure out how to deal with matters that seem uninteresting, like compliance.

Now, take a look at what a typical test looks like. Prick a finger, you get some blood, about 50 microliters. That's about all you're going to get. Because you can't use the usual sort of systems. You can't manipulate it very well, although I'll show something about that in a moment. So, you take the drop of blood, no further manipulations. You put it on a little device. The device filters out the blood cells, lets the serum go through, and you get a series of colors down in the bottom there. And the colors indicate disease or normal. But even that is complicated. Because to you, to me, colors might indicate normal. But after all we're all suffering from probably an excess of education.

What you do about something which requires quantitative analysis? And so the solution that we and many other people are thinking about there, and at this point there is a dramatic flourish, and out comes the universal solution to everything these days, which is a cell phone. In this particular case, a camera phone. They are everywhere, six billion a month, in India. And the idea is that what one does, is to take the device. You dip it. You develop the color. You take a picture. The picture goes to a central laboratory. You don't have to send out a doctor. You send out somebody who can just take the sample. And in the clinic either a doctor, or ideally a computer in this case, does the analysis. Turns out to work actually quite well, particularly when your color printer has printed the color bars that indicate how things work.

So, my view of the health care worker of the future is not a doctor, but an 18 year old, otherwise unemployed who has two things. He has a backpack full of these tests, and a lancet to occasionally take a blood sample, and an AK47. And these are the things that get him through his day.

There is another very interesting connection here. And that is that what one wants to do is to pass through useful information over what is generally a pretty awful telephone system. It turns out there is an enormous amount of information already available on that subject, which is the Mars rover problem. How do you get back an accurate view of the color on Mars, if you have a really terrible bandwidth to do it with? And the answer is not complicated but it's one which I don't want to go through here, other than to say that the communication systems for doing this are really pretty well understood.

Also, a fact which you may not know, is that the compute capability of this thing is not so different from the compute capability of your desktop computer. This is a fantastic device which is only beginning to be tapped. I don't know whether the idea of one computer, one child makes any sense. Here is the computer of the future. Because this screen is already there and they're ubiquitous.

Alright now let me show you just a little bit about advanced devices. And we'll start by posing a little problem. What you see here is another centimeter sized device. And the different colors are different colors of dye. And you notice something which might strike you as a little bit interesting, which is the yellow seems to disappear, get through the blue, and then get through the red. How does that happen? How do you make something flow through something? And, of course the answer is, "You don't." You make it flow under and over.

But now the question is, how do you make it flow under and over in a piece of paper? And the answer is that what you do, and the details are not terribly important here, is to make something more elaborate, you take several different layers of paper, each one containing its own little fluid system, and you separate them by pieces of, literally, double sided carpet tape, the stuff you use to stick the carpets onto the floor. And the fluid will flow from one layer into the next. It distributes itself, flows through further holes, distributes itself.

And what you see at the lower right-hand side there is a sample in which a single sample of blood has been put on the top, And it has gone through and distributed itself into these 16 holes on the bottom, in a piece of paper, basically it looks like a chip, two pieces of paper thick. And in this particular case we were just interested in the replicability of that. But that is, in principle, the way you solve the "fever of unexplained origin" problem. Because each one of those spots then becomes a test for a particular set of markers of disease. And this will work in due course.

And here is an example of a slightly more complicated device. There is the chip. You dip in a corner. The fluid goes into the center. It distributes itself out into these various wells or holes, and turns color. And all done with paper and carpet tape. So, I think it's as low-cost as we're likely to be able to come up and make things.

Now, I have one last, two last little stories to tell you, in finishing off this business. This is one. One of the things that one does occasionally need to do is to separate blood cells from serum. And the question was, here we do it by taking a sample. We put it in a centrifuge. We spin it, and you get blood cells out. Terrific. What happens if you don't have an electricity, and a centrifuge, and whatever? And we thought for a while of how you might do this. And the way, in fact, you do it, is what's shown here. You get an eggbeater, which is everywhere. And you saw off a blade. And then you take tubing, and you stick it on that. You put the blood in. You spin it. Somebody sits there and spins it. It works really really well.

And we said that we did the physics of eggbeaters and self aligning tubes and all the rest of that kind of thing, sent it off to a journal. We were very proud of this, particularly the title which was "Eggbeater as Centrifuge." (Laughter) And we sent it off, and by return mail it came back. I called up the editor and I said, "What's going on? How is this possible?" The editor said, with enormous disdain, "I read this. And we're not going to publish it, because we only publish science." And it's an important issue because it means that we have to, as a society, think about what we value. And if it's just papers and phys rev letters, we've got a problem.

Here is another example of something which is -- This is a little spectrophotometer. It measures the absorption of light in a sample The neat thing about this is, you have light source that flickers on and off at about 1,000 hertz. Another light source that detects that light at 1,000 hertz. And so you can run this system in broad daylight. It performs about equivalently to a system that's in the order of 100,000 dollars. It costs 50 dollars. We can probably make it for 50 cents, if we put our mind to it. Why doesn't somebody do it? And the answer is, "How do you make a profit in a capitalist system, doing that?" Interesting problem.

So, let me finish by saying that we thought about this as a kind of engineering problem. And we've asked, what is the scientific unifying idea here? And we've decided that we should think about this not so much in terms of cost, but in terms of simplicity. Simplicity is a neat word. And you've got to think about what simplicity means. I know what it is but I don't actually know what it means.

So, I actually was interested enough in this to put together several groups of people. And the most recent involved a couple of people at MIT, one of them being an exceptionally bright kid who is one of the very few people I would think of who is an authentic genius. We all struggled for an entire day to think about simplicity. And I want to give you the answer of this deep scientific thought. (Laughter) So, in a sense, you get what you pay for. Thank you very much. (Laughter)