The Amazing World of Microscopes: A Window to the Invisible

HPSm...Xris

28 May 2024

In the vast universe of science, there is a tool that has revolutionized our ability to explore the unexplored, to see the invisible: the microscope. This instrument, which seems straight out of a mystery novel, is actually the most faithful ally of the scientist, the educator and the curious. Today, we immerse ourselves in the fascinating world of microscopes, where the best brands compete to offer a clearer vision of the microcosm.

Nikon, Zeiss, Leica, The Optical Giants

When we talk about microscopes, there are names that resonate with the force of an echo in the mountain. Nikon, known for its excellence in cameras, is also a pioneer in the manufacture of high-quality microscopes⁴. Their models, such as the Nikon Eclipse E200, are the envy of laboratories and educational classrooms. But Nikon is not alone in this race; Zeiss, with its legacy dating back to 1846, remains a titan in the field, offering innovations that seem to defy the laws of physics.

Advantages and Disadvantages: The Double Side of the Coin

Like all technology, microscopes have their pros and cons. The magnification and resolution capacity of these devices allows us to observe everything from cells to microorganisms, opening doors to more precise medical diagnoses and advances in nanotechnology. However, not everything is rosy; Optical microscopes require light and can be expensive, while electronic microscopes, although more powerful, can kill living organisms during observation.

The Cost of Precision: How Much Is It Worth Seeing the Unimaginable?

The million dollar question is: how much does it cost to enter this microscopic world? Prices vary widely, from inexpensive beginner microscopes to professional equipment that can exceed thousands of euros. But beyond the cost, what really matters is what these instruments allow us to discover: a universe hidden from our eyes, but not from our curiosity.
Electron Microscopes: The Look Beyond the Visible

Electron microscopes, like detectives of the tiny, allow us to explore a world that escapes human sight. Unlike their optical cousins, which use visible light, electron microscopes use beams of electrons to reveal the secrets of the microscopic. Get ready for a journey to the heart of the matter!

Types of Electron Microscopes

1. Transmission Electron Microscope (TEM)

The TEM is the Sherlock Holmes of microscopes. How does it work? Imagine you have an extremely thin sample, like a sheet of biological tissue. The TEM sends a beam of electrons through this sample. The electrons that pass through are collected by a detector and used to create an image on a screen or photograph. The resolution is astonishing, allowing us to observe details at the atomic level. Furthermore, TEM not only shows us the structure, but also allows us to analyze the chemical composition using techniques such as energy dispersive X-ray spectroscopy (EDX).

2. Scanning Electron Microscope (SEM)

The SEM is like an artist who paints the topography of the samples. Instead of passing through the sample, the SEM scans its surface with a beam of electrons. As the electrons interact with the sample, they generate signals such as backscattered electrons, secondary electrons, and characteristic x-rays. These signals are collected and used to create an image on the screen. SEM provides us with high-resolution three-dimensional images and is applied in materials, biological sciences and geology research. In addition, it also allows chemical analysis and determination of elemental composition using X-ray electron microscopy (XEDS).

What Are Electron Microscopes Used For?

These electronic detectives have revolutionized science and medicine. They let us:
- Explore cells and microorganisms: From viruses to cellular organelles, nothing escapes your gaze.
-Investigate materials: What is inside a material? How are its atoms organized? Electron microscopes tell us.
- Advance in nanotechnology: The manipulation of materials at the atomic scale is possible thanks to these tools.

In short, electron microscopes are windows into the invisible, revealing a microscopic cosmos full of wonder. So, the next time you look at an enlarged image, remember that you are seeing beyond what your eyes could dream of. Welcome to the world of the tiny and the grand. 🌟
Preparation of Samples for Electron Microscopes: Discovering the Invisible

Electron microscopes, with their ability to reveal the secrets of the microscopic world, require meticulous sample preparation. Here I will guide you through the essential steps to prepare samples for both transmission electron microscope (TEM) and scanning electron microscope (SEM).

Transmission Electron Microscope (TEM)

1. Chemical Fixation:
- Treat the sample with a fixing agent to maintain its structure and prevent it from disintegrating during observation.
- Common fixatives include formaldehyde, glutaraldehyde and osmium tetroxide.

2. Washing:
- Wash the sample to remove any residual fixative and other contaminants.

3. Dehydration:
- Remove water from the sample to avoid the formation of bubbles during observation.
- Uses a series of increasing concentrations of alcohol or acetone to dehydrate the sample.

4. Inclusion in Resin:
- Embed the sample in a plastic resin (such as epoxy resin) to make it more rigid and easier to cut.
- The resin also helps maintain the structure of the sample during the cutting process.

5. Cutting and Polishing:
- Cut thin, uniform sections of the sample using an ultrathin microtome.
- Then polish the sections to obtain a smooth and transparent surface.

6. Observation in TEM:
- Place the sample in the TEM microscope.
- Electrons pass through the sample and create an image on a screen or photograph.

Scanning Electron Microscope (SEM)

1. Sample Preparation:
- The sample must be dry and conductive (usually coated with a thin layer of metal, such as gold or platinum).
- Mount the sample on a suitable support.

2. Electron Scanning:
- The SEM uses a beam of electrons to scan the surface of the sample.
- Electrons interact with the sample and generate signals (backscattered electrons, secondary electrons and characteristic X-rays).

3. Screen Image:
- The collected signals are used to create a high-resolution three-dimensional image on the screen.

Conclusion

Preparing samples for electron microscopes is an art and a science. Each step is crucial to obtain clear and detailed images. So, the next time you look at a microscopic image, remember that behind it there is a meticulous process that allows us to see the invisible. 🌟
In conclusion, microscopes are much more than just tools; They are passports to a world waiting to be discovered. And while makes and models may vary, the thrill of exploration is universal. So the next time you look through an eyepiece, remember that you are seeing further than any human eye has ever seen before. Welcome to the amazing world of microscopes!