经济学人449:医用植入设备 一个甜美的想法

 　　Science and technology.

　　科技。
　　Medical implants 2.
　　医用植入设备。
　　A sweet idea.
　　一个甜美的想法。
　　Researchers are trying to harness glucose 3-the body's own fuel-to power implantable gadgets 4 such as pacemakers.
　　研究人员正试图利用葡萄糖-人体自身的燃料-作为像起搏器这样的可植入设备的能源
　　LIKE any other electrical device, a pacemaker needs a power source. Since the first permanent pacemaker was installed in 1958, manufacturers of implantable medical devices (IMDs) have tinkered with many different ways of supplying electricity to their products. A variety of chemical batteries have been tried, as well as inductive recharging schemes and even plutonium power cells that convert the heat from radioactive decay into electricity. Plutonium-powered pacemakers still turn up from time to time in mortuaries and hospitals, and a failure to dispose of them properly keeps America's Nuclear Regulatory Commission busy handing out citations 5 to unsuspecting hospitals.
　　和其他所有的电子设备一样，一个起搏器同样需要能源。自从1958年第一个永久起搏器被植入后，可植入医疗设备的制造商就在不断尝试为其产品提供电能的各种方法。尝试了各种化学电池以及感应充电计划，甚至是将放射衰变的热能转换为电能的钚电源单元格。现在，钚电源起搏器还是时不时的出现在停尸房和医院中，并且使得美国核管理委员忙于忙于处罚那些疏于妥善处理钚电源起搏器的医院。
　　Today, non-rechargeable lithium-based batteries are common. Used in many cardiological and neurological implants, they provide between seven and ten years of life. That is more than enough: the speed of medical progress is such that by the time the battery has run down it is generally time to replace the whole device with a newer model in any case.
　　如今，不可充电的锂电池较为普遍。应用在心脏病和神经源性疾病的移植设备中，一般能够提供7年到10年的使用时间。这么长的使用时间显得绰绰有余：医学发展的速度意味着等到设备的电量用光就到了用一个更先进的型号来替换整个设备的时候。
　　But that has not dissuaded 6 researchers from continuing to seek perfection, in the form of a compact, perpetual energy source which does not require external recharging. Now, several researchers are closing in on just such a solution using glucose, a type of sugar that is the main energy source for all cells in the body.
　　然而这并没有阻止研究人员继续寻找完美的，紧凑型的永久能源，从而使得这些移植设备不再需要外部充电。现在，几个研究人员正在接近一个能够提供这样能源的方法，使用葡萄糖，即为人体所有细胞提供主要能源的一种糖。
　　Many other ideas have been tried down the years. The kinetic 7 energy of the human body, for example, has long been harnessed to power watches, and should also be enough to keep a pacemaker ticking. Temperature differences between the body and the ambient air mean that thermoelectric couples can generate useful quantities of juice. A properly tuned 8 device could capture background radio-frequency energy and rectify 9 it into small amounts of usable power.
　　这些年还有许多其他想法也被尝试。比如，很久以前人体动能就用来为手表提供能量，这种动能也足够维持起搏器的运转。人体与外部环境的温差意味着热电偶能够产生一定数量能量。一个适当调谐装置能够捕获北京射频能量并且将其转换成少量可用能源。
　　Although all these ideas have been shown to work in theoretical tests on lab benches, they all suffer from the same handicap: intermittent 10 operation. Unconscious patients, for instance, generate little kinetic energy. Sitting in a warm room reduces the power available from thermocouples. And radio waves are common but not ubiquitous. These are serious drawbacks for an IMD that may be responsible for keeping someone alive.
　　尽管这些想法在实验的理论测试中运转正常，但是他们都有一个同样的缺陷：间歇运行。例如，处于昏迷的患者产生的人体动能很少。处于温暖的房间中会减少热电偶产生的可用能量。另外射频很常见，但是也不是处处可见。这些问题对于维持生命的可移植医疗设备来说都是十分严重的缺陷。
　　Power in the blood.
　　血液中的能量。
　　A glucose-powered implant 1 would solve such problems. Glucose is continuously delivered throughout the body by its circulatory systems. A sugar-powered device would therefore have access to a constant supply of fuel, and could be implanted almost anywhere.
　　而一个葡萄糖供能的移植设备可以解决这些问题。葡萄糖由人体的循环系统被源源不断的输送到人体各处。一个糖分供能的设备因此能够取得持续供给的能量并且几乎可以在任何位置进行移植。
　　One approach, which has been employed by Sameer Singhal, a researcher at the CFD Research Corporation in Alabama, involves the same enzymes 11 that break down glucose within a living cell. Using carbon nanotubes, he and his colleagues immobilised two different enzymes on the electrodes of a fuel cell, where they generated electricity by freeing electrons from glucose. At present, only two of the 24 available electrons in a single glucose molecule 12 can be harnessed, but refinements 14 to the technology should boost that number.
　　就职于Alabama的CFD Research Corporation的研究人员Sameer Singhal所使用的方法涉及利用酶将活细胞中的葡萄糖分解。利用碳纳米管，他和他的同事在燃料电池的电子上找到了2种不同的酶，在燃料电池中他们通过释放葡萄糖的电子来产生电能。现在，在一个葡萄糖分子中的24个可用电子中只有2个可以利用，但是对这项技术的后续完善应该会使得可以利用的电子数量有所增加。
　　Dr Singhal has implanted prototype devices into live beetles 15. Fitted with a fuel cell about the size of a penny, the bionic bugs 16 were able to generate over 20 microwatts (20 millionths of a watt) during a two-week trial.
　　Singhal博士将设备原型移植进了甲虫活体。放入了一个一便士大小的能量池，这些甲虫在2周实验期内产生了20微瓦（一瓦特的百万分之二十）。
　　That is only around a fifth of the power that a pacemaker requires, but Dr Singhal reckons that a human-sized version of his cell would be able to deliver enough juice. There is a catch, though: a process called biofouling, in which foreign objects implanted in the body become encrusted with proteins and tissue. That could render Dr Singhal's device inoperable after only a few months. Equally worrying are the enzymes, which tend to break down over time. Losing enzymes means losing power.
　　这只是一个起搏器所需能量的15分之一，但是Singhal博士认为人类体积大小的细胞量能够产生足够的能量。这里有个欠缺点：被称做生物污垢的过程，即被移植进人体的外来物会嵌入蛋白质和组织中。这会使得Singhal博士的设备在移植后的几个月内便无法使用。同样使人担忧的是酶，这种物质随着时间的推移会被分解。而丢失酶就意味着丢失能量。
　　Rahul Sarpeshkar, an electrical engineer at the Massachusetts Institute of Technology, has a solution to both these problems. In a paper published on June 12th in Public Library of Science, Dr Sarpeshkar and his colleagues describe building a glucose fuel cell which uses a platinum 18 catalyst 19 that does not degrade over time.
　　一位MIT的电子工程师Rahul Sarpeshkar有个方法可以解决这两个问题。6月12号发表于Public Library of Science的一篇论文中，Sarpeshkar博士和他的同事证实用铂催化剂打造的葡萄糖能量池，其效果不会随着时间被削弱。
　　The downside is that platinum is a less efficient catalyst than the enzymes used by Dr Singhal, and so Dr Sarpeshkar's cell works less well. But it might be able to generate enough electricity to run the next generation of ultra-low-power IMDs.
　　该方法的缺点是铂催化剂与Singhal博士所用的酶相比效率不高，因此，Sarpeshkar博士的能量池运转效果不好。但是它也许能够生产足够的电能来运转下一代超低功耗的可移植医疗设备。
　　Dr Sarpeshkar also has a novel solution to the biofouling problem: implant the fuel cell in the cerebrospinal fluid (CSF) surrounding the brain. Although the CSF has only half the glucose concentration of the bloodstream, it is virtually free of the proteins and cells which would foul 17 a device implanted in other areas of the body, and thus its life would be greatly extended.
　　另外，Sarpeshkar博士还有一个针对于生物燃料问题的新型解决方法：在大脑周围的脑脊液（CSF）中植入能量池。尽管脑脊液仅含有体液中葡萄糖浓度的一半，但是这样做几乎可以使其免于植入人体其他部位而被蛋白质和细胞包围的命运，因此使其使用寿命大大延长。
　　Other approaches could yield more energy. Some soil-dwelling bacteria have evolved to deposit the electrons from glucose oxidation onto iron molecules 20, which allows researchers to trick them into living on the anode of a fuel cell. A colony of microbes like these, properly isolated 21 from the host's immune system, might be coerced 22 into trading electrons for nutrients 23 from the bloodstream. The bacteria can renew their own enzymes, so such a system should last indefinitely. But the idea of implanting a bacterial 24 colony into a patient might be a tricky 25 one to get past medical regulators-not to mention public opinion.
　　其他一些方法则需要更多的能量。用一些土壤细菌将葡萄糖氧化过程所产生的电子安置在铁分子上，这样研究人员就可以诱使这些细菌存活在能量池的阳极上。像这样的克隆微生物，与寄主的免疫系统相分离，可能被迫的用电子与体液交换营养成分。细菌可以重新激活他们自身的酶，因此这样的系统能够永久的持续下去。然而将细菌克隆体移植进病人的身体这种想法可能无法通过医疗监管人员的监管，就更不要说公众舆论了。
　　A better idea might be to retrain some of the body's own cells to do the work. Just as an outdated 26 procedure called a cardiomyoplasty involved severing 27 a seldom-used upper-back muscle and wrapping it around the heart to assist in pumping blood, muscle fibres might be retrained to crank an electromechanical generator 28. Such a setup would be capable of producing enough electricity to drive even the most power-hungry of devices, like artificial hearts.
　　一个更好的想法可能是将一些人体自身的细胞进行再培训来完成这个工作。正如一个已过时的手术，叫做心肌成形术，将较少用到的上背部肌肉切断并将它包络再心脏周围来协助心脏输送血液，肌肉纤维也许可以经过在训练后来驱动机电发电机。这样的方法能够产生足够的电能来驱动哪怕是最耗费能源的设备，比如人造心脏。
　　The energy density 29 of lithium batteries has come a long way in the past few decades, but the chemical reaction on which they rely will never be able to match the energy available from the metabolisation of glucose. The chemical energy in a gram of glucose is nearly half the amount available from petrol, a famously energy-dense fuel. With a bit of refinement 13, sugar could prove a very sweet solution for powering the next generation of IMDs.
　　在过去的几十年间，锂电池的能量密集度取得了长足的发展，但是锂电池所依赖的化学反应永远也无法产生与葡萄糖代谢所产生的能量相匹敌的数量。一克葡萄糖所含有的化学能量相当于半克汽油能产生的能量，原油是众所周知的能源密集型燃料。再经过一点优化，糖就有可能为下一代可移植医疗设备的能源问题提供一个十分完美的解决办法。