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Image of microplate for article on microplate reader function.
Published On: March 29th, 2022

Microplate readers measure changes in biochemical, cellular or physical properties in the wells of a plate. Microplate readers are designed for a standard 96 well plate, but there are some plate readers available for other plate sizes. As lab automation increases, adherence to a standard microplate size is critical so that automated systems can handle the plates.

Microplates were originally developed in the 1950s, but it wasn’t until the advent of lab robotics equipment in the 1980s and 1990s that these plates became standardized. Wondering what a microplate reader measures? Keep reading to discover the answers to many microplate reader questions.

What Does a Microplate Reader Measure?

A microplate reader predominately measures ultra-violet or visible absorbance, luminescence, and fluorescence. Absorbance is the measurement of how the substance in each well absorbs light in a given wavelength.

Luminescence is the measurement of how much light is emitted by the substance in each well. Fluorescence is also a measurement of emitted light when exposed to a fluorescence light source. The source wavelength is slightly different then the emitted light, allowing the emitted light to be measured separately from the source.

Single-mode microplate readers can only measure 1 of these characteristics, while multimode microplate readers can measure three or more modes. A multimode microplate reader will facilitate research without taking up a large benchtop footprint if a lab has a wide range of assays to run.

How Does a Microplate Reader Work?

A microplate reader is a spectrophotometer that uses a limited range of wavelengths. Microplate readers shine a light source through a filter or a monochromator, then the filtered beam is directed to the plate. Light passes vertically through the pate wells, hitting a detector that transmits information about the wavelengths in the sample to a computer.

It’s important to make sure that the same amount of liquid is in each well, because microplate readers use the path length that light travels through to calculate each measurement. If one well is more full than another, the microplate reading might not be accurate. For this reason, most labs use microplate readers in conjunction with automated liquid handling systems.

What Are the Applications of Using a Microplate Reader?

Applications vary depending on the microplate measurement in question. In general, microplate readers are excellent tools for protein-related assays. Microplates are famous for ELISA assays, but there are applications for all three measurement types.

A microplate reader measures the three qualities of absorption, luminescence, and fluorescence.

The most common absorbance applications are protein quantification, including ELISA, DNA or RNA quantification, and Bradford assays. Luminescence is useful in a wide range of assays, including cell viability, cytotoxicity, protein interaction via BRET, and enzymatic reaction assays. Finally, fluorescence measurements can be used for protein interaction via FRET, flux and signaling, and gene expression assays.

What is a Microplate Handling System?

A microplate handling system is a lab automation tool that can help access, stack, and store microplates. These systems usually feature a robotic arm that gently moves plates between storage areas and microplate readers. A microplate handling system can work with liquid handling equipment, barcode labels and scanners, incubators, and plate washers.

Contact Hudson Robotics to request a quote, choose a microplate handling system, or learn about other lab automation tools.