Basic information about microplate readers
What is a Microplate Reader?
A microplate reader is a laboratory instrument that is used to measure chemical, biological or physical reactions, properties, and analytes within the well of a microplate. A microplate consists of small wells in which separated reactions take place. In the microplate, these reactions convert the presence of an analyte or the progression of biochemical processes into optical signals. The microplate reader is an optical system that detects these signals and thus quantifies the parameter of interest.
Scientists in the life sciences and pharmaceutical industries (e.g., drug discovery) strive to improve routine laboratory processes and efficiency by using products or instruments able to save time. A microplate reader can handle up to 3456 samples in minutes or even seconds. A plate reader helps to minimise operational time and to save reagent costs, allowing researchers to focus more on data analysis and the generation of actionable insights.
What is a microplate reader used for?
A microplate reader is used for the quantification of several biological and chemical assays in a microplate. Nowadays, the availability of a plethora of reagent kits enables the exploitation of a microplate reader in different fields and for many different applications. Besides biological, cellular, biochemical, pharmaceutical research and drug discovery, both in academic and industrial environments, plate readers are also used in drug discovery, environmental research, and in the food or cosmetics industry.
Working principle of a microplate reader
A microplate reader detects light signals produced within a specific wavelength range by samples that have been pipetted into a plate. The optical properties of these samples are the result of a biological, chemical, biochemical, or physical reaction. Different analytic reactions result in different optical changes used for analysis. Absorbance, fluorescence intensity, and luminescence are the most popular and most frequently used detected modes in laboratories worldwide. Additionally, advanced modes such as fluorescence polarization, time-resolved fluorescence, and AlphaScreen® are also available on microplate readers.
Microplate-based measurements detect light signals produced by a sample, converted by a sample, or transmitted through a sample. In the plate reader, the signal is measured by a detector, usually a photomultiplier tube (PMT). PMTs convert photons into electricity that is then quantified by the microplate reader. The output of this process is numbers by which a sample is quantified.
Depending on the nature of the optical signals and consequently on the measurement mode, samples on a plate may need to be excited by light at specific wavelengths. This light is usually provided by a broadband xenon flash lamp. To allow specific excitation of the sample, the light produced by the lamp is selected by a specific excitation filter or monochromator. On microplate readers, to increase sensitivity and specificity, the optical system can employ filters or monochromators on the emission side. These are usually placed between the sample and the detector. The optical system combined with the PMT determines the wavelength range of the reader.
