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Our own experiences

with a scanning electronmicroscope

It all started when the three team members met in Esslingen, Germany. Actually Esslingen and the M–erike Secondary Grammar School is the headquarters of ThinQuest Team No. 11473.
Esslingen is a middle-sized town not far from Stuttgart in Baden-W¸rtemberg. It has different kind of secondary schools and for those who want to go on with their studies there is a collage for technology (Fachhochschule f¸r Technik). This collage has a scanning electronmicroscope. There are lectures for the students about the structure and the operation of this machine. We took part in one of them.

And then one day we recieved a package by post. I had the great honour to open it. My hands were shaking as I opened the package. I opened it and carefully took out three small boxes. Those boxes included the base of our work - the mites. They were mites which lice in the nose and ears of animals. But couldn't have done anything without an electronmicroscope. Actualy it is amusing to examine mites under lightmicroscopes as well because you can see them crawling around but you cannot reach a big amplification so you cannot make that fascinating photos. With a scanning electronmicroscope the world of tiny creatures is no longer a mistery.

It is a great luck to be allowed to work with a microscope like that. They cost a lot of money so it can be understood that the owners would like to take good care of them so only a few people are allowed to use them. For example when my brother learned that I was allowed to operate a machine like that he almost went crazy. He attends the University of Veterinary Science so they study about microscopes. At the university they have a transmissional electronmicroscope but the students were only allowed to approach the machine to a safe distance of 5 meter.

The first hard task is to take the mites out of the boxes. You have to heat them to 40 degrees but you cannot use fire. We put these water-proof boxes into warm water which had the proper temperature. After about ten minutes the mites start to crawl towards the top of the boxes.

Than it is our turn. We must put them on the mount. As they are too small you must not use tweezers because they would be flattened completely. I used a small piece of paper. I put it in front of the mite and it simply crawled onto the paper. When it reached the edge of the paper I tried to get it on the mount which had a sticky layer on it so that the mites cannot go away. Sometimes it was not as easy as it sounds but I could put 7 mites on the mount.

Because the mites are not good conducters you have to cover them with a conductive layer. Normally they use coal or gold. In our case we used a thin (3 mm) gold layer. The machine which does this procedure uses vacuum. Unfortunately those mites (which live in animals) which we had conained too much water And that was the problem we had to face. In the machine the water escaped from the mites and they looked as if they have been smashed. We could see it with the lightmicroscope as well. We made a try with the electronmicroscope and there we could see the ruins of my one and a half hour hard work. (You can see a photo like that among our photos.)

My first try ended in failure. I made two more samples with 20 mites on both of them. Luckily I could do it quite fast because at that time I already had experience in putting mites on the moult. Mr Brennenstuhl (a teacher of the collage) suggested a drying method. We should put the samples in a minus 2-3 degree medium. In the collage they only had a deep-freeze which is too cold. So the two samples were lit by a lamp in the deep-freeze.

We waited 4 days till we tried the first sample. I was excited when I had a look at the sample. Another failure! They still had too much water and collapsed again. I was quite disappointed. I saw many nice mite photos before and I could not make not even similar to them. But I sill had one more sample. The last hope.

After about one and a half weeks we put the last hope in the machine. Another exciting ten minutes followed. At last! The covering procedure is ready! I quickly put it under the lightmicroscope. I found some collapsed mites but some of them were OK.

We put it in the electronmicroscope and then I could roam free among the small creatures. It was fascinating to see those small animals so big on the green screen. I do not know how long I was handling the microscope. I really enjoyed it. To take one picture I needed one minute. It could have been done faster but it would have gone at the expense of quality. I hope now you are excited and qurious about our photos