Problem: Bulk microplate-based liquid dispensing instruments typically use peristaltic pumps or microprocessor- controlled syringe pumps to perform reagent and cell dispensing. Each pump type has advantages and disadvantages depending on the reagent used and the laboratory’s needs. Users must often choose between the technologies, thus limiting their assay choice. If they require both types, labs often incur extra expense and reduced lab space to purchase multiple instruments.

BioTek’s MultiFlo™ Microplate Dispenser combines one or two peristaltic pumps and two syringe bulk dispensers into one compact instrument.

Solution: However, some instruments, such as BioTek’s MultiFlo™ Microplate Dispenser, combine one or two peristaltic pumps and two syringe bulk dispensers into one compact instrument to expand assay choice and flexibility and limit instrument purchases. A variety of vessel types are compatible with such instruments, including 6- to 1536-well microplates, deep-well plates and low volume plates, and the dispensing volume range is 1 μL to 3 mL. The modular design means that users may purchase one dispensing type now and add the other dispensing types in the future when assay requirements change.

The peristaltic pump technology uses flexible tubing and rollers affixed to a rotor that compresses the tubing, containing fluid, at regular intervals to force out a measured liquid dose. The dose volume is dependent on the roller distance, tubing tension, internal diameter and dispenser tip geometry. Advantages of peristaltic pump dispensing are: a fully contained sterilizable fluid path and multiple channels that dispense several liquids without cross-contamination or compatibility issues. Additionally, low prime volumes and the ability to back-flush conserve precious reagents and cells. However, the disadvantages of peristaltic pump dispensing include reduced compatibility with high viscosities and fractional rather than full volume dispensing. Recalibration and replacement tubing also add to the long-term instrument cost.

Syringe dispensers are controlled by microprocessors and feature a faster output than mechanical peristaltic pump dispensers along with high accuracy and precision. Additionally, there is no fluid output pulse and the flow rate is fully controllable—from gentle cell dispensing to vigorous reagent dispensing. Syringe dispensers do not require consumables or routine calibration, thus making them particularly well suited for high throughput batch processing workflows. Disadvantages of syringe dispensing are that more prime volume is required and the volume range may be more limiting than the range offered by peristaltic pump dispensers.

A bulk liquid dispenser offering peristaltic pump and syringe dispensing in one unit, coupled with automation and stacking compatibility, provides increased assay flexibility and throughput and saves valuable bench space.

For more information, visit www.biotek.com