Two classes of instrument are sold under overlapping names and they solve different problems. A dispenser delivers the same liquid into many wells from a bulk reservoir, quickly and with no sample to keep track of; a handler picks up different liquids from named positions and puts them somewhere else, which is a much harder problem and a much larger machine. Most laboratories that describe a bottleneck have a dispensing problem, and a dispenser costs a fraction of a handler, so it is worth being precise about which one the work needs before anybody quotes.
Choosing a laboratory dispenser by the reagent rather than the plate
A peristaltic cassette is cheap, easy to clean and the tubing is a consumable; a syringe based dispenser is more accurate at small volumes and has wetted parts that have to suit the reagent; a non contact dispenser can place nanolitres and cares about viscosity and surface tension. The reagent decides which of the three is possible, and a cell suspension rules out anything that shears it. Ask for a dispensing precision figure at YOUR volume in YOUR reagent rather than the headline, because the specification is quoted where the instrument looks best.
When a multi dispenser pipette is enough, and what a reagent dispenser adds
A repeating hand pipette dispenses many aliquots from one aspiration, which is most of the benefit for a few plates a day at a fraction of the cost and no footprint. It stops being enough when the plate count makes the wrist the limit, when a plate has to be filled in a uniform time because the assay is kinetic, or when the volume is below what a person can place reliably. A bulk dispenser also frees the person entirely, which is worth more than the seconds saved when the same person is watching a reader.
Where automated liquid handling instruments stop being dispensers
The moment the instrument has to know WHICH liquid is where, it needs tips, a deck, labware definitions and a method, and all four are the real cost. That is the step change in price and in the time before it works: a dispenser is running the afternoon it arrives, a handler is a project with a person attached. So the honest test is whether the task is one liquid into many wells or many liquids into chosen wells; only the second needs the larger machine.
Reading a pipetting robot price, and what the quote leaves out
The instrument is often the smaller half. Tips at a per plate cost, labware carriers for every plate type you use, the software licence and its seats, integration with a reader or a sealer, installation, qualification and the first year of service are quoted separately often enough that two quotes for the same machine are not comparable as they arrive. Ask for a first year total against a named protocol, and ask what a second protocol costs to write, because that number decides whether the machine gets used for anything but the first application.
A robotic liquid handling system against a liquid handling machine
The words describe the same class and vendors use both, so compare decks, channels and software rather than names. Used equipment is a genuine saving here because the mechanics outlast the software: the questions are whether the version still runs on a supported operating system, whether the vendor will sell a service contract on it, and whether the labware definitions and methods transfer. An instrument whose software cannot be licensed to you is a deck with arms.
An automated liquid dispenser laboratory teams keep using
Adoption, not specification, is what decides whether one of these is used a year later. The instruments that stay in use are the ones where a person can change a protocol without the vendor, where the consumables are on the normal ordering list, and where a failure at four in the afternoon has a documented recovery rather than a support ticket. Ask to see somebody who is not an application specialist run the instrument during the evaluation, and ask what happens when the run stops halfway.
Questions people ask about liquid dispensing system
Dispenser or handler for a 96 well assay?
A dispenser if every well gets the same reagent, a handler if the samples differ per well. Many assays need both, and the cheaper order is to buy the dispenser first and see whether the bottleneck moves, because it usually does.
Does a non contact dispenser avoid cross contamination?
It avoids tip contact with the well, which removes one route and not all of them: aerosols and reservoir contamination remain, and the reagent path still has to be cleaned between liquids. It is a real advantage for a single reagent over many plates and not a licence to skip cleaning.
How much of the cost is consumables?
Enough to change the comparison. Tips for a handler and cassettes or syringes for a dispenser are recurring, and a tip strategy of washable against disposable is the largest single lever on the running cost. Price a year of the intended throughput before choosing between two instruments.
Are used liquid handlers worth buying?
Often, because the mechanics outlast the software. The questions that decide it are whether the software version still runs on a supported operating system, whether the vendor will sell a service contract on that serial number, and whether the labware definitions and methods transfer. An instrument whose software cannot be licensed to you is a deck with arms.