Walk into any modern biomedical, pharmaceutical, or clinical laboratory, and you will almost certainly find a microplate reader for laboratories either running an assay or waiting for one. These instruments measure optical signals from hundreds of wells simultaneously, producing quantitative data that individual cuvette-based measurements could never generate at comparable speed or scale. From ELISA to nucleic acid quantification to cell viability assays, the microplate reader is the analytical instrument that makes high-throughput laboratory science practical.
This guide covers what microplate readers actually measure, the detection technologies available, the plate formats supported, and how to evaluate and select the right model for your laboratory.
What A Microplate Reader Measures
A microplate reader is a benchtop laboratory instrument that measures optical signals from wells in a microplate to quantify biological, chemical, or physical events. According to BMG Labtech’s technical documentation, microplate readers support a wide range of assays including ELISA, enzyme activity, cell viability, DNA/RNA and protein quantification, protein-protein interaction assays, and reporter gene assays.
The measurement principle depends on the detection mode. For absorbance measurements, the reader passes light of a selected wavelength through the sample and measures how much is transmitted, calculating absorbance from the ratio of incident to transmitted light according to the Beer-Lambert Law. For fluorescence, the reader excites fluorescent molecules with a specific wavelength and measures emission at a longer wavelength. For luminescence, the reader measures light produced by a chemical reaction without external excitation.
Detection Modes: Choosing The Right Technology
Absorbance (colorimetric) detection is the most commonly used mode in routine laboratory settings. ELISA assays, protein quantification methods including Bradford and BCA assays, enzyme activity assays, bacterial growth monitoring, and DNA/RNA quantification via intercalating dye methods all use absorbance-based detection. Most ELISA assays are measured at 405, 450, or 492 nm, with a reference measurement between 590 and 630 nm.
Fluorescence intensity detection provides significantly greater sensitivity than absorbance for applications where fluorescent labels or dyes are used. Cell viability assays using fluorescent reagents, nucleic acid quantification using dyes that bind specifically to double-stranded DNA, and high-sensitivity protein quantification all benefit from fluorescence detection’s ability to detect analytes at concentrations far below absorbance detection limits.
Luminescence detection measures light produced by enzymatic reactions, most commonly the luciferase-luciferin reaction used in reporter gene assays. According to Berthold Technologies’ technical documentation, luminescence is the most popular technology for reporter gene assays and is also used for cell proliferation and protein-protein interaction studies. Luminescence detection offers extremely high sensitivity because there is essentially no background signal, unlike fluorescence, which always carries some level of background autofluorescence.
Multi-mode readers integrate two or more of these detection technologies into a single instrument. For labs conducting diverse assay types, a multi-mode reader eliminates the need for separate dedicated instruments, reduces bench footprint, and provides flexibility to adapt to evolving assay needs without additional capital investment.
Plate Formats Supported
The microplate reader for laboratories typically supports 96-well plates as the standard format, but many models also accommodate 24-well, 48-well, and 384-well formats. The 384-well format enables assay miniaturization for higher throughput, reducing reagent consumption significantly compared to 96-well formats. High-throughput drug screening environments may use 1,536-well formats supported by specialized high-sensitivity readers.
Filter-Based Vs Monochromator-Based Wavelength Selection
Filter-based readers use physical optical filters to select the measurement wavelength. According to Berthold Technologies, filter-based systems typically deliver higher transmittance at selected wavelengths, providing better sensitivity for specific applications like ELISA where the measurement wavelength is fixed and known in advance. They are also generally more affordable than monochromator systems. Monochromator-based readers select wavelength continuously across a range, enabling full spectral scanning. This flexibility is essential for applications where optimal measurement wavelength varies or where spectral characterization of samples is required.
Key Features To Evaluate
Sensitivity and dynamic range determine whether the reader can accurately measure your samples across the full concentration range of interest. Measurement speed affects throughput for high-volume labs. Software capabilities for data analysis, including curve fitting for ELISA standard curves, are essential for regulated clinical environments. Plate injection accuracy affects well-to-well CV values. For regulated labs, 21 CFR Part 11 compliance and audit trail functionality may be required.
The Stat Fax 4700: A Purpose-Built Elisa Reader
The Stat Fax 4700 ELISA Microstrip Reader from NE LabSystems is a purpose-built absorbance reader designed for clinical diagnostic labs running routine ELISA assays. It reads 96-well plates and individual microstrips, supports the standard ELISA wavelengths, and provides the straightforward, reliable performance that clinical labs depend on for patient-facing diagnostic results. It is backed by NE LabSystems‘ free extended warranty on U.S. purchases. Browse the full reader range or call (877) 733-6838 to discuss which model fits your assay types and throughput requirements.