Well plates: sizes, variants and their application in the lab

Microtiter plates are a standard consumable in every laboratory

Microtiter plates such as 96-well plates are widely used in laboratories.

Well plates, also known as microplates or microtiter plates, come in sizes ranging from 6-well to 1536-well. They are available in sterile, plasma-treated, or untreated versions to accommodate various applications. Their broad usage has led to a wide variety of product variants.

The evolution of well plates

The now indispensable well plate, or microtiter plate, originated in the 1950s Hungary (1) and has since become a laboratory essential worldwide. Initially developed as a 6 × 12 format with 72 wells (2), modern versions now include 6, 12, 24, 48, 96, 384, and 1536-well formats. Their applications range from analytical research and biological studies to high-throughput screening (HTS), including drug discovery assays. Over time, dedicated equipment such as plate readers and pipetting robots has emerged to support well plate-based workflows. The original 72-well design has largely been replaced by standardized formats, each with varying well capacities, ranging from microliters to several milliliters.

Standardization of well plate dimensions

By the late 1990s, numerous well plates were commercially available, each following the same fundamental concept: a plate with cavities designed to hold liquids or solids. However, size variations across manufacturers posed challenges for automated laboratory systems, as differing dimensions caused compatibility issues (3-6). Recognizing the need for standardization, the Society for Biomolecular Screening mandated consistent well plate dimensions. In 2004, the Society for Laboratory Automation and Screening (SLAS), in collaboration with the American National Standards Institute (ANSI), established four industry-wide standards governing the 96, 384, and 1536-well plate formats (3-6). These formats are predominantly used in screening applications.

Well plate applications in cell culture

Well plates with 6 to 48 wells are primarily used in cell culture studies, where larger well sizes facilitate cell growth and maintenance. Compared to petri dishes or T-flasks, well plates provide the advantage of handling multiple samples simultaneously, improving efficiency in experimental workflows.

6-well plates and petri dishes are used in cell culture studies

Well shapes and surface treatments

Beyond well plate sizes, their well shapes and surface treatments vary to meet specific laboratory requirements. Flat-bottom wells are preferred for optical measurements due to their clear and even surface. U-bottom wells, with their curved shape, support homogeneous sample mixing, while V-bottom wells concentrate liquids at a single point, facilitating sample recovery and concentration. C-bottom wells combine the advantages of flat and U-bottom designs, offering better sample mixing while maintaining an optimal surface for optical readings (7).

Surface treatments further customize well plates for specialized applications. Coatings with proteins, peptides, or polymers enhance cell attachment and bioactivity. Plasma treatments modify surface hydrophobicity or hydrophilicity, tailoring plates for adherent or suspension cell cultures. Additionally, sterilization methods such as gamma irradiation or ethylene oxide treatment ensure well plates meet aseptic processing standards.

Specialized well plates for fluorescence and luminescence assays

Some well plates are designed to improve sensitivity in fluorescence and luminescence-based assays. Black plates reduce background interference, improving signal-to-noise ratios in fluorescence applications, while white plates enhance luminescence readings by reflecting emitted light. These features make them indispensable in high-sensitivity screening workflows.

Sterility and material considerations

Sterile well plates are essential for cell culture applications and cell-based ELISAs (enzyme-linked immunosorbent assays). The material composition of a well plate varies based on experimental requirements. Plates used for PCR applications must withstand high temperatures, making polypropylene the preferred material to standard polystyrene. Today’s well plate market offers customized solutions for nearly every laboratory application.

Sustainability in well plate manufacturing

Well plates are predominantly single-use products, leading to significant plastic waste. The biopharmaceutical and life sciences industries are actively exploring sustainable alternatives to reduce environmental impact.

In 2024, Green Elephant Biotech introduced a 96-well plate made from biopolymer polylactic acid (PLA) as a sustainable alternative to conventional plastic plates. The use of PLA reduces the carbon footprint by 50% compared to polystyrene, an improvement driven by CO₂ absorption during plant-based PLA production and the material’s energy- and water-efficient manufacturing process.

Initially launched as a transparent, non-sterile F-bottom plate, additional black and white versions were introduced to support various assay applications. Do you use non-sterile F-bottom plates? Take a look at Green Elephant 96-well plates to get more information on sustainable 96-well plates, their performance, and fields of application.

References

(1) Takátsy, G. (1955). The Use of Spiral Loops in Serological and Virological Micromethods. Acta Microbiologica et Immunologica Hungarica, 3, 191–202

(2) Sever, J. L. (1961). Application of a Microtechnique to Viral Serological Investigations. U.S. Department of Health, Education, and Welfare, Public Health Service, National Institute of Neurological Diseases and Blindness, Perinatal Research Branch. Bethesda, Maryland.

(3) ANSI/SLAS. (2012). ANSI/SLAS 1-2004 (R2012): Microplates – Footprint Dimensions (formerly ANSI/SBS 1-2004). Society for Laboratory Automation and Screening (SLAS)

(4) ANSI/SLAS. (2012). ANSI/SLAS 2-2004 (R2012): Microplates – Height Dimensions (formerly ANSI/SBS 2-2004). Society for Laboratory Automation and Screening (SLAS).

(5) ANSI/SLAS. (2012). ANSI/SLAS 3-2004 (R2012): Microplates – Bottom Outside Flange Dimensions (formerly ANSI/SBS 3-2004). Society for Laboratory Automation and Screening (SLAS).

(6) ANSI/SLAS. (2012). ANSI/SLAS 4-2004 (R2012): Microplates – Well Positions (formerly ANSI/SBS 4-2004). Society for Laboratory Automation and Screening (SLAS).

(7) Zähringer, H. (2020). Von Nullachtfünfzehn bis plasmabeschichtet Produktübersicht: Mikrotiterplatten. Laborjorunal 4/2020