If you cut yourself, your options are to reach for a plaster or, if the cut is nasty, to go to a doctor to have it stitched or glued. That seems a rather limited choice. Medical researchers have been trying to develop another way to join the edges of a wound, inspired by something routinely done to gas pipes and electronics: soldering.

如果你割傷了自己，你的選擇是拿膏藥，或者，如果傷口很嚴重，去找醫(yī)生縫合或粘合。這似乎是一個相當有限的選擇。醫(yī)學(xué)研究人員一直在嘗試開發(fā)另一種連接傷口邊緣的方法，其靈感來自于天然氣管道和電子產(chǎn)品的常規(guī)做法：釬焊。

And an innovation developed at the Swiss Federal Institute of Technology (ETH) in Zurich, in co-operation with the Swiss materials science institute Empa, suggests this might soon become a practical reality. In soldering, an intermediate material is heated until it melts and bonds with the two surfaces that are to be joined. The material of these edges has a higher melting point and remains solid (otherwise it would count as welding).

位于蘇黎世的瑞士聯(lián)邦理工學(xué)院(ETH)與瑞士材料科學(xué)研究所Empa合作研發(fā)的一項新方法表明，這可能很快成為現(xiàn)實。在釬焊過程中，中間材料被加熱，直到它融化并與要連接的兩個表面結(jié)合。這些邊緣的材料具有較高的熔點，并保持固態(tài)(否則將算作焊接)。

For tissue, the intermediate material is not a metal alloy, but a paste of biocompatible material, such as albumin, a protein that is an important constituent of blood. When heated, the paste develops chemical bonds with living tissue on both sides. As healing progresses, the two sides reconnect and the paste is removed by the body's natural cleaning procedures.

對于組織來說，中間材料不是金屬合金，而是一種生物相容性材料的糊狀物，比如白蛋白，一種血液的重要組成部分。當加熱時，糊狀物與兩側(cè)的活組織形成化學(xué)鍵。隨著愈合的進展，兩側(cè)重新連接，通過身體的自然清潔程序?qū)⒑隣钗镆瞥?/p>

Closing wounds by soldering has several important advantages, says Oscar Cipolato, a PHD candidate at ETH, who presented preliminary results on April 5th at the Photonics Europe conference in Strasburg, France. The bond it produces is strong and watertight, something that cannot be guaranteed with stitches. If a wound is internal—after surgery, for instance—a leak could cause an infection.

4月5日，在法國斯特拉斯堡舉行的歐洲光子會議上，ETH的博士候選人Oscar Cipolato展示了初步結(jié)果，他說，通過釬焊來縫合傷口有幾個重要的優(yōu)勢。它產(chǎn)生的粘合劑是堅固和防水的，這是不能通過縫線來保證的。如果傷口是內(nèi)部的——比如手術(shù)后的傷口——滲漏可能會導(dǎo)致感染。

But soldering tissue has turned out to be difficult in practice, which means it is not commonly done. Heating the soldering paste is done by shining a laser onto it, from which the paste absorbs energy. But controlling the heating precisely is tricky. The paste needs to reach about 80°c to work. If the temperature is too low, the soldering material will not fully melt and the bond will be weak. But if it is too high, it risks burning the surrounding tissue.

但是焊接組織在實踐中被證明是困難的，這意味著它不是通常做的。加熱焊接膏是通過激光照射它，從它吸收能量。但精確控制加熱是很棘手的。膏體需要達到大約80°c才能工作。如果溫度過低，焊錫料就不會充分熔化，粘結(jié)也會薄弱。但如果劑量過高，就有灼傷周圍組織的風(fēng)險。

Existing attempts at wound-soldering rely on thermal imaging to measure temperature. But that only measures the temperature at the surface of the solder, rather than throughout the material. Mr Cipolato and Inge Herrmann, a chemical engineer at ETH, hope their improved paste can get around such problems. It is made up of two kinds of nano-particles, specks of material of only about 20 billionths of a metre across.

現(xiàn)有的繞焊嘗試依賴于熱成像來測量溫度。但它只測量了焊料表面的溫度，而不是整個材料的溫度。Cipolato先生和ETH的化學(xué)工程師Inge Herrmann希望他們改良后的糊狀物能解決這些問題。它是由兩種納米粒子組成的，它們是直徑僅為200億分之一米的物質(zhì)微粒。

between them, these help direct the energy of the laser to the places it should be, and help doctors gauge the conditions in the paste. The first set of particles are made of titanium nitrate. They eagerly absorb photons of red or near infrared light, precisely the colours that most easily penetrate living tissue, and release the energy as heat to their surroundings.

在它們之間，這些幫助引導(dǎo)激光的能量到它應(yīng)該在的地方，并幫助醫(yī)生測量膏狀物的條件。第一組微粒是由硝酸鈦制成的。它們急切地吸收紅色或近紅外光的光子，正是最容易穿透活組織的顏色，并將能量以熱的形式釋放到周圍環(huán)境。

That efficient absorption means the paste can be heated by a relatively weak laser beam, which helps protect the surrounding tissues. Using such tiny particles is in itself not new. But until recently most researchers used tiny rods of gold, which are expensive. Nanoparticles of titanium nitrate, on the other hand, are easily and cheaply produced by spraying the right mix of precursor chemicals into a flame. The second set of particles are a new development in the soldering world.

這種有效的吸收意味著這種膏體可以用相對微弱的激光束加熱，這有助于保護周圍的組織。使用如此微小的粒子本身并不是什么新鮮事。但直到最近，大多數(shù)研究人員使用的都是昂貴的小金條。另一方面，通過向火焰中噴灑合適的前體化學(xué)物質(zhì)混合物，硝酸鈦納米顆粒的生產(chǎn)很容易，成本也很低。第二組粒子是焊接界的新發(fā)展。

They are specks of a material which fluoresces. In other words, it absorbs the laser light, but immediately re-emits the energy as light again, at a few very specific wavelengths. Two of these wavelengths are also in the infrared and red colour range. That allows some of the re-emitted light to emerge from the paste to where it can be analysed by an external instrument called a spectrometer.

它們是一種能發(fā)出熒光的物質(zhì)的斑點。換句話說，它吸收了激光，但立即將能量以光的形式重新發(fā)射出來，只是波長非常特定。其中兩種波長也在紅外和紅色范圍內(nèi)。這使得一些重新發(fā)射的光能夠從漿糊中顯現(xiàn)出來，并被一種叫做分光儀的外部儀器分析。

By precisely measuring the difference between the two wavelengths, the temperature of particles that are emitting it—and thus of the paste as a whole—can be worked out. Thus far, the researchers have tested the technique only on pieces of pig intestine that they obtained from a slaughterhouse. Soldering a cut is done in a matter of minutes.

通過精確測量兩種波長之間的差值，發(fā)射粒子的溫度就可以計算出來——因此整個粒子的溫度就可以計算出來。到目前為止，研究人員只在屠宰場獲得的豬小腸上測試了這項技術(shù)。焊接切口只需幾分鐘。

Similar “ex vivo” tests of the strength and permeability of the bond will also be needed for human tissue, followed by clinical tests on actual pigs and, eventually, humans. But the researchers are optimistic. At the conference, they were cagey about exactly what the fluorescing particles are made of. They are applying for a patent, which could be quite valuable if the tools at the ready in a doctor’s office one day include a laser soldering gun.

人體組織也需要進行類似的結(jié)合強度和滲透性的“體外”測試，然后在豬身上進行臨床測試，最終在人身上進行。但研究人員對此持樂觀態(tài)度。在這次會議上，他們對熒光粒子的構(gòu)成諱言甚少。他們正在申請一項專利，如果有一天醫(yī)生辦公室里準備好的工具包括激光焊接槍，那么這項專利將非常有價值。