Microplate washers: how can washing steps between incubations be made more reliable?

Indispensable in ELISA and immunoassay workflows, microplate washers automate the dispense, soak and aspirate steps with buffers. The result: reduced background, tight CVs and reproducibility that holds up across shifts and operators. Adjustable needle heights, per-well residual volume control, multi-cycle protocols and anti-drip features minimise analyte loss and cross-contamination. 96/384-well formats, U/V/flat-bottom plates, stored methods and LIMS connectivity keep routine work flowing while easing the load on staff.

What types of microplate washers are there?

Two main families define the category: the instrument – microplate washer and the software for microplate washers. Washers deliver programmable sequencing of cycles (fill, incubate, aspirate, rinse), with fine control of flow rates, soak time and needle height. Standard ELISA models handle 96-well plates (sometimes 384-well), U-/V-/flat-bottom plates, and offer central, ring or side aspiration modes to minimise the residual volume and protect biomolecules.

For magnetic beads, dedicated washers immobilise the beads via a magnetic plate, enabling gentle and reproducible washes without loss. In cell culture, programmes with a flow-rate ramp, off-bottom aspiration and controlled agitation prevent cell detachment. On the fluidics side, you will find multiple lines (2 to 4 buffers), level sensing, anti-siphon, purge and self-cleaning routines to prevent fouling.

The software then takes over to design, validate and document methods: protocol library, user rights, audit trail and 21 CFR Part 11 compliance options. USB/Ethernet connectivity, log export and LIMS integration safeguard quality and traceability.

Key selection criteria:
• Plate format and bottom types (U/V/flat), 96/384 compatibility
• Target residual volume and dispense precision (CV)
• Number of buffer lines, anti-drip, needle rinse
• Aspiration modes, height/offset adjustment, variable flow rates
• Maintenance routines, access to consumables, footprint and noise level
• Software, traceability, user profiles and IT integration

Type	Principle	Applications
Standard ELISA washer	Aspiration/dispensing via needles, programmable cycles	ELISA, 96-well colourimetric assays
Magnetic bead washer	Magnetic immobilisation, gentle washes	Bead-based immunoassays, multiplex
Cell washer	Controlled flow rates, off-bottom aspiration	Fixation, staining, gentle washes
Control software	Methods, audit trail, integrations	Traceability, 21 CFR Part 11, LIMS

In which applications is a microplate washer used?

• Life Sciences / R&D: immunoassays, antibody quantification, biomarker validation with low CVs.
• Pharmaceutical & biotech: immunoassay readout screening in 96/384-well plates, standardised and fully traceable methods.
• Agri-food: ELISA screening of allergens, mycotoxins and residues with low background.
• Environment: plate-based assays for toxins, cyanobacteria and pesticides; multi-buffer management.
• Cosmetics: plate-based compatibility and irritation tests; gentle washes for cell cultures.
• Chemistry & quality control: standardised washes for protein-ligand binding and colourimetric methods.
• Analytical laboratories: increase throughput, reduce operator-to-operator variability and end-to-end traceability.

The different types of laboratory washing systems and available software

Frequently asked questions about microplate washers

How do I choose the right microplate washer?
Check plate formats (96/384), aspiration modes, residual volume, number of buffers, precision, maintenance requirements and traceability needs.

Can 384-well plates be washed?
Yes, if the instrument is designed for it. You will need a suitable wash head/manifold and needles, well controlled flow rates, and sufficient precision for microvolumes.

How can I minimise cell loss?
Use low-flow programmes, aspirate slightly above the well bottom, keep soak/incubation times controlled and, if available, enable gentle, programmable shaking.

What are good maintenance practices?
Purge at the end of the day, rinse with deionised water, use compatible cleaning solutions, and replace tubing and filters regularly.

How do I reduce cross-contamination?
Use anti-drip features, rinse needles between cycles, adjust probe heights precisely, and perform regular maintenance to prevent build-up and leaks.

Are harsh solutions compatible?
Check the chemical compatibility of wetted materials (needles, tubing). Prefer non-corrosive buffers and rinse immediately after use.

Can the software support compliance?
Software suites provide audit trails, rights and role management, and electronic signatures, useful for environments operating to or close to 21 CFR Part 11.