Once in our lifetime, we have all watched a show where a sample is slipped under the microscope mounted on a tray to carry out a test. Those small pieces of glass or plastic are known as Microscopic Slides. Even though on TV, they don’t get the spotlight, but in labs – they are one of the essential tools.
A microscope slide is a small piece of glass on which different substances are placed for inspection under a microscope. The substance can be a cell or a tissue section placed on a microscopic slide to make and observe a sample. Before being observed, a coverslip is placed on the specimen, and other chemicals are added for various purposes. The object to be examined is placed on the slides, then the slides go under the microscope for examination.
Microscope slides are a crucial component in science, as any and all experiments are incomplete without them. Moreover, they enable scientists, microbiologists, and bio-engineers to conduct rapid tests in today’s increasingly biologically advanced world Microscope slides enable these tests and the resultant knowledge that benefits humankind.
Microscope slides are of different kinds. They are not all of the same material, thickness, or corner type. Instead, various kinds of microscope slides are made as per the requirements of the specimen being tested. The properties of a microscope slide are determined by the nature of the specimen to be observed. For this reason, microscope slides are prepared using different glass materials and sizes, etc., to suit the specimen.
Here are some instructions for the preparation of slides and specifications of properties that are applied in the making of various kinds of microscope slides:
Microscope slides can be made from these types of glass:
- Sheet glass
- Float glass (normal float glass and super white float glass)
Sheet glass has a green shade to it, and float glass is white in color. Float glass transmits more light than sheet glass, and its flatness is also considered better than sheet glass. Both of them have their merits, and their selection depends on needs.
Economy slides for general use, sheet glass is preferred. For color frosted slides and charged slides, float glass is preferred
The standard thickness of microscope slides is 1.0-1.2mm. It may vary, but this measurement is optimum for ordinary microscopes for durable usage.
Some common sizes of microscope slides are 1 “*3”, 25mm*75mm, and 26mm*76mm. Other special sizes are also available for special purposes. Some of them are thin sections (48mm*28mm), geological use (75mm*50mm), and petrographic use (46mm*27mm)
A microscope slide has one of these three types of edges:
- Ground Edge
- Cut Edge
- Beveled Edge
Ground edges are of two types: 90º shape and 45º shape. The former works well with automatic equipment, and their simple sides make it easier for them to be picked up with grippers. On the other hand, the latter is also easy to hold and smear a blood sample on both manually and automatically. Both the forms of edges differ only a little from each other. It is recommended to use ground edges slides of 90º when the substance on the slide is infectious as they provide higher safety levels due to their ease of grip.
The most economical choice is that of cut edge; they are also perfect for daily or routine usage. Although the equipment in which it is being used is automatic, then there exists a risk of them breaking.
Beveled edges in microscope slides have 45º ground edges that ensure an even smear on the slide. Their corners are clipped, and they come in a standard size.
- Clipped corner
As explained above, the corners of microscope slides have an angle that makes them safe for handling and gripping. The ground edged slides come in both 90º shape and 45º shape and serve appropriate purposes for equipment and specimen. As far as clipped corners are concerned, they make gripping the slides easier and more secure as compared to those with a definite angle.
Plain, Frosted and Charged
Microscope slides can be:
Some slides have frosted ends as it makes them less sticky in certain cases and reduces the chances of them getting jammed in equipment. The frost also lets the scientists label the slides if they need to, as labeling makes the process of identifying a lot easier on the go. Frosted slides are also surface treated to make the cell cultures adhere to them and have more wettability. This makes dealing with the specimen a smooth process and saves time.
Double frosted slides are frosted on both sides for convenience and usability; they can be labeled on both sides. Frosted slides can be colored too for labeling purposes, as dividing samples by colors saves time. On the other hand, plain slides are economical; frosted slides make work easier and more practical in the lab.
Some microscope slides also come with a charged surface. The purpose of charged slides is better to sample adhesion. Slides with positive charges make their surface perfect for the adhesion of specimens of all kinds. Samples usually have a negative charge which attracts them to the positively charged slides and ensures a long-lasting and reliable adhesion on the surface of the slide. Charged slides reduce what is called float, the tendency of the sample to shift on the slide.
Paper interleaved and non-paper interleaved
Microscope slides are either:
- Paper interleaved, or
- Non-paper interleaved
Paper interleaved slides are those slides that have papers placed between them for safety and protection. The papers are placed between slides to prevent them from sticking, accumulating scratches over time, and any fungus infection on the surface. Paper interleaved slides are usually the economic ones.
Non-paper interleaved slides are comparatively costlier.
There are more than one ways to pack, ship, and buy microscope slides. They are bought in bulk. Contingent on needs and frequency, the following are the specifications of bundles in which microscope slides are available:
- 50pcs per pack, 50packs per case
- 72pcs or half gross per pack, 20packs or 10gross per pack
- 100pcs per pack, 30packs per case
The shelf life of microscope slides without Paper is related to the production technology, but it is at least 18 months. Interleaved slides tend to have a longer shelf life due to greater protection and less wear-off. The shelf life of microscope slides with Paper is about three years, owing to the added protection.
It is best to use the old stock of microscope slides first instead of letting them rest in the warehouse. The newer the product, the more efficient it is. Do not store a pack of slides for too long, as that increases the chances of wear and tear. Stay mindful of the expiry date of the stock, and do not let it go to waste.
Storage Of Slides
Keep them away from heat or harsh atmospheric conditions. The storage environment should be cool and dark. Keep them away from heat and other extreme conditions. Handle carefully while loading and unloading as they are fragile.