How Microplate Sealers Are Used In The Lab

Microplates also called microtiter plates are banks of test-tubes called wells which facilitiate the testing and analysis of multiple samples at one time. Microplates can be made of many substances though polystyrene plastic is the most common and polypropylene is used when the plate is expected to withstand thermo-cycling or low temperature storage.

The first microplate was designed by Hungarian, Dr. G. Dr. G. Takatsky in 1951. It had 72 wells and was made out of Lucite. American John Liner brought microplates into mainstream usage later in the '50s by introducing a 96 well styrene vacuum-formed panel in 1953 and later developments and improvements have been made to microplates ever since.

Microplates can be used individually and manually but since their standardisation in the 1990's they are an essential part of any automated laboratory environment, fitting seamlessly into a chain of connected instruments which together work towards greatly amplifying the number of tests being made and decreasing the chance of human error.

One such machine is the microplate sealer. In order to store or transport samples safely the microplate needs to be sealed to protect the contents from contamination or protect technitions or the environemt or exposure to potentially harmful material. Because microplate sealers cap each individual well in a plate, they also ensure that samples do not contaminate each other.

When comparing sealers, you will often see the terms ANSI or SBS used to describe the plates with which it will work. These acronyms refer to the American National Standards Institute and the Society for Biomedical Screening. These two bodies have determined the sizes of standard footprints for all microplates and PCR microplates which makes it possible to confidently select laboratory equipment secure in the knowledge that it will work with currently owned instruments.

Thermal Microplate Sealers

With a thermal sealer, a hot plate is driven down on the microplate surface and the seal applied with heat and pressure. It is important that the right kind of microplate is used because should it have a raised rim, it might interfere with the sealing contact.

Thermal sealers require microplates that are made of a heat resistant material like polypropylene. Acrylic microplates would not be suitable.
Different sealing inserts ship with some thermal microplate which are used under flexible microplates to support them and lend them more rigidity to ensure a more uniform seal.

Adhesive Microplate Sealer

Another option is an adhesive sealer which utilises pressure-sensitive adhesive film (PSA) and would be used in cases where samples are sensitive to changes in temperature. As with thermal sealers, different sealing tape is available depending on the samples to be contained. Some are appropriate for use with PCR microplates and others are not.

The question of which sealer to buy is always going to be application based. It is important to consider not ony whether samples are heat-sensitive but also the quantity of microplates used over time. Microplate sealers can be semi-automated or fully automated and handle anything from 10 to 50 microplates a day to many hundreds of plates. As a microplate sealer may represent a significant outlay, both current and future applications should be taken into account.