Microplate readers are used to monitor samples via the measurement of light within a microtiter plate, for a variety of applications. Microtiter plates are flat plates with typically 6, 24, 96 up to 3456 wells. The key microplate readers and subsequent read modes are as follows:

Microplate readers can be purchased as single mode or multimode, combining several read modes on a single instrument.

Fluorescence based plate readers can be either filter or monochromatic. Both types are employed in generating Excitation wavelength via interference filters or monochromators - which include diffraction gratings and prisms. It is important to explore the advantages and disadvantages to suit your application. Generally monochromators are well suited for absorbance measurements and do not require special filters, however optical properties are said to be inferior to that of interference filters.

Your current and future applications should determine your exact requirements.

If you work within a life science laboratory, you may be using a microplate reader for applications such as gene expression for molecular biology, cell signaling, ELISAs, protein and nucleic acid quantification techniques, cell growth assays and immunoassays.

For labs working on high throughput screening of compounds and targets, speed and sensitivity is often a concern. You may require very specific screening solutions and lower limits of detection over a large number of microplates. The ability to measure all wells of a microplate at once is a factor to consider alongside reliability, sensitivity and consistency, essential for high throughput. Consider also the quality of resolution for imaging cell populations within an individual well.

The type of specific microplate applications that will be performed is a consideration. Homogenous assays with even well distribution applications require the well to be read from the top and center, with single end point measurements. Cell based assays require bottom reading, orbital average, well-scanning as well as features enabling incubation and shaking of the plate. Also of consideration is the type of microtiter plate your lab currently uses and whether these will integrate with the microplate reader.

Many microplate readers have application-specific features, such as full spectrum absorbance measurement, low volume measurement, gas vents, dual emission detection, dynamic range of absorbance, plate shaking and in-situ incubation.

The option to upgrade an instrument is also a valid factor to consider. Single mode readers are less expensive than multi-mode, advantageous for start-up applications. As techniques develop, microplate reader requirements may change. You should discuss with the manufacturer how easy it is to upgrade its instruments. The difference between single or multi-mode detection can be a budget vs future application consideration.

Consider the demands of the instrument, how many operators it will require, whether it is a shared resource and how it will integrate into your current workflow (is it stand alone or fully integrated). The various options to integrate using stackers and fully automated systems, for higher throughput with less operator involvement, can be discussed with reader manufactures and other independent specialist suppliers.

Limitations resulting from the compatibility of software with external hardware are important. Some systems include integrated software with features such as inbuilt protocols and the ability to select languages. Software should be validated to global standards.

Other considerations can include the number of users, length of usage, flexibility, ease of use, reliability, budget and customer support.

Taking into consideration current and future trends is essential in maximizing the lifespan of the reader. As systems become more sophisticated, integration, convenience and application specificity will be key. Systems will include integral features such as the ability to create specific in-situ conditions without the need to remove plates between steps. Systems will also become faster and more efficient and be able to run a variety of different assays.

Application possibilities will increase as manufacturers work to provide solutions to individual and industry demands, such as those currently being requested in the food/beverage and biofuels industries, as well as in emerging countries.

Manufacturers are taking into consideration customer feedback and requirements, with many developing strategies for even greater specificity assays and technology for the future.

Whether purchasing a microplate reader for a new application, or replacing an existing system, there are a number of factors to consider. Once you have examined current and future application needs, the detection mode, reader type and specific features will determine your exact specifications.

However as there are many readers available, manufacturers will welcome the opportunity to discuss your applications and specifications in detail as many applications can be enhanced with the correct instrument and integration into your current lab.