Electron Microscopes


Our world is composed of various living or biotic, and non-living or abiotic, things, and we, humans have always been curious. We want to know what makes things up and how they came to be. Humans develop questions and ways on how to answer them. We discovered science and it is now our friend. 

Advancements made our lives easier and more comfortable as we learn so much. We make discoveries and inventions, and what helped us make breakthroughs, except for brilliant minds, are the pieces of equipment made for the development of science. Various inventions and innovations through the years made great leaps in physics, chemistry, biology, and others. These tools helped us do things, which were once impossible.

A great example of a fine and powerful tool made to aid science is the microscope. It helps us view things that are not visible to the naked eye. It made the discovery of various minuscule things that make up larger objects possible. However, one of the first types invented, the optical microscope, has limitations like its low magnification, which prevents it from viewing nanoscale objects. It can only give a magnification of up to 1000x, leaving out many other important details that a scientist needs. To solve that problem, the invention of the electron microscope made some things possible. It is here to aid us in our experiments.

Brief History

An electron microscope is a powerful tool for many. It can provide 1000x to 2000x magnification with a high resolution. It is essential to various fields of science including Biology, Nanotechnology, Medicine, and Forensics. It might be costly, large, and needs maintenance, but it still plays a vital role for our scientists and their experiments.  

Ernst Ruska working

Ernst Ruska (1906-1988) invented the electron microscope in 1931. He was a German engineer and professor. He thought that electron microscopy is a solution to the limitations of optical microscopes. Ruska applied his wide knowledge of electron wavelengths to make a powerful microscope. He was studying at the Technical University of Munich, under Dr. Max Knoll, and they developed the first electromagnetic lens.

Like other prototypes, their first product did not differ too much from an optical microscope. It is only in the late 1930s that Ruska was able to make significant modifications to make a more powerful microscope. He was hired by the Siemans Company as an electrical engineer and later produced the first electron microscope. In 1986, he won the Nobel Prize for Physics for his work on the electron microscope, along with Gerd Binnig and Heinrich Rohrer, for their scanning tunneling microscope design. 

The electron microscope significantly improved some aspects that we need for science. We can now observe and discover the little things that make up our environment. Until today, the electron microscope is hailed as one of the most powerful tools for imaging, it is only surpassed by the atomic force microscope. 

Process of Electron Microscopy

The electron microscope uses the concepts of the optical microscope, but instead of light or photons, it utilizes electrons. When using it, the specimen should be prepared in a vacuum chamber. You can view it on the screen, as it uses electromagnets and a thermionic gun to produce the electron micrograph. It needs a low vacuum or variable pressure chamber to uphold the pressure differential, so you cannot place it just anywhere. It will require computer interfaces and software for digital display and analysis.

As stated earlier, samples to be observed has to be prepared. Various techniques may be used, but most of these will require special training. Some processes you may do are staining, embedding, sectioning, cryofixation, dehydration, and others. Ensure that your sample undergoes a technique suitable for it, so you can view it correctly. That is because the electron microscope requires a high vacuum environment.  

Introduction to electron microscopy

Producing the Nanoscale Image 

To produce images, the electrons from the beams that pass through the thermionic gun interact with the specimen. The coils inside the microscope bend the beams to create the display. When these electrons hit the sample, they will get the size, shape, surface texture, arrangement of atoms, and others. The information gathered is then processed to produce the image. You can improve the resolution by increasing the voltage

Nanoscale Pore through a microscope

Types of Electron Microscope

Transmission Electron Microscope

The transmission electron microscope has many similarities with an optical microscope, but it can produce images for samples that are one nanometer in size. It needs a high voltage to increase resolution and produce a black and white display that can be transferred to a photographic plate or viewed on a screen. However, its resolution suffers from spherical and chromatic aberrations, but still, it is a great tool for nanotechnology.

Scanning Electron Microscope

The use of a scanning electron microscope is on providing topographical information or the physical features of a material. Its coils or solenoids make the beam scan symmetrically on the surface of the sample to produce the image. It is ten times less powerful than a transmission electron microscope but creates a black and white display with significantly higher resolution.

Maintaining the Electron Microscope

 The electron microscope may be large, expensive, and requires the user to have the training, but it is a huge help for science. It has to be placed in a special room designed for it. It has to be free from disturbances that might tamper with its image production since it is highly sensitive. You have to make sure it has what it needs to function, like sufficient voltage, current, and cool water. Maintaining it is also essential, so do what is necessary to keep it in great condition. 

Scientific advancements are possible because of the powerful tools of innovation. It is a good thing that Ernst Ruska invented fine equipment that people can use for different fields. If you are a scientist and want to take your experiments to the next level, you may invest in your own electron microscope. It will surely be worth it.