Liquid handling/pipetting is one of the most common laboratory processes. Thus, it is the procedure that is the most commonly automated when considering laboratory automation systems. Automating your liquid handling steps has many benefits. It improves precision, accuracy and consistency as well as minimizes human error, improves lab workflow, and reduces ergonomic injuries. Deciding on the needed components for a successful automated liquid handler will depend on your process and applications.

When should you consider automating liquid handling?

  • When sample/plate loads move from a few or dozen to hundreds/thousands
  • When throughput needs move from 5-10 samples/plates per day to 20-100+ samples/plates per day
  • When transfer volumes are too small to handle consistently or precisely
  • When you need more reproducible outcomes
  • When additional labor costs are a concern
  • When the risk of repetitive stress injuries increases
  • When there are safety issues regarding handling infectious or hazardous sample
  • When you plan on implementing a fully automated robotic lab automation system

Evaluate your process

Before making any decision on the purchase of a robotic liquid handler it’s essential to evaluate the process(es) to be automated. Do you have a well-defined and robust process? Are you doing sample preparation, serial dilutions, normalizations or just some simple reagent transfers? What are the fluids and volumes to be transferred? What labware will be used? How many transfers need to be completed per hour or per day? Will the current throughput need to increase in the future? Is walk-away time important and how much. How much bench and lab space do you have? Are there any unique parameters that need to be taken into account? These are just a few of the key questions that should be defined prior to purchase and deciding how a liquid handler will integrated into your current process

Costs/options

Today’s laboratory automation systems industry offers a wide variety of robotic liquid handler options and configurations. The costs for a liquid handler can range from as little as $5000 to over $300,000. The choice of options is numerous, such as the number of pipettes, number of pipetting, arms deck size, barcode scanning, robotic plate movers, shakers, vacuum manifolds, and the list goes on. The more features your process needs, and the higher the cost of the instrument.

Liquid parameters/Liquid Classes

The type of liquids tested in research and analytical labs can vary greatly. Fluids tested can be as thick as molasses to a fast-flowing organic solvents such as chloroform. When pipetting these extremes by hand a person can adapt and make visual adjustments to the hand pipette. Successful liquid transfers involve knowing the type of liquid and accounting for its behavior in a particular environment. When programming automated liquid handlers you must know everything about the liquid, such as viscosity, density, surface tension, cohesion, and vapor pressure. To accommodate for these variance, automated liquid handlers’ software has settings known as liquid parameters or liquid classes. These can consist of a few key parameters (speed, air gap, delay, break off speed) to as many as 25 different settings. Some liquid handlers can automatically adjust liquid parameters on the fly (adjusting for low viscosity fluids that may drip) or notify the user of clot in a pipette tip. If you are pipetting difficult fluids or have need of some advanced feature, be sure to investigate the various liquid class parameters that the various liquid handlers offer.

Configurations

Size of instrument and Deck layout: Due to the multitude of liquid handlers on the market means there are a multitude of configurations to choose from. Choosing the appropriate liquid handler for your process can be a challenge. Available Laboratory square footage and lab bench space always seem to be a challenge. Considering the instrument deck size is one of the first considerations. If you are putting the instrument in a fume hood, smaller and shorter instruments should be considered. If integrating into a larger automated system, you may also want to consider smaller footprint instruments as fewer deck locations will be needed. If you’re not integrating the liquid handler to an automated system but want more walk-away time when operating the instrument. Then choose something with as many nest locations as possible.

Pipette configuration: Your process will dictate the type, number, and configuration of the pipette head(s). The process could dictate that you need a single channel pipette, or a fixed 8 channel or expandable 8 to 16 channels. Or it could indicate that s multi-tip head in a 96, 384 or even a 1536 format. Maybe having an instrument with both single channels and a 96 head is the best option.

Transfer technology: Most liquid handlers on the market use either liquid or air displacement. Each has advantages depending on the application. Air displacement is ideal for dispensing volumes over a large volume range, from 0.5 to 1000μL. Air displacement works best with disposable tips. Liquid displacement works well with volumes below 5 ul or for multi-dispensing small volumes. It can work well with fixed and disposable tips. There are also a couple of other technologies on the market. One that uses vacuum and positive pressure with an incorporated microchip that can instantaneously calculate the volume of liquid entering or leaving a tip. Another technology utilizes acoustics to transfer fluid from one plate to the next. Each of these technologies are useful for the right application.

Robotic labware mover: Some vendors offer an additional feature of a robotic arm or robotic labware mover in addition to the pipetting features. This feature can be a boom or bust depending on your process or application. Some of these plate movers take up needed worksurface space and may block availability of all plate nests. Others are less obtrusive and do not interfere with nest locations. In addition, these are typically not fast at moving tips or labware around on the work surface. If you are needing a high throughput, an external robot arm may be a better choice. On the positive side the plate mover does add a great deal of protocol flexibility to a liquid handler as it can allow you to add other peripheral devices to give you some process integration at a lower cost.

Software for laboratories and control of liquid handlers: Control software for today’s liquid handlers have gone through multiple version upgrades over the past 20 years. It’s safe to say that most if not all the graphical user interfaces are very easy to use. If you need some special programming, say something like smart pipetting (barcode ID coupled with work-listing), most vendors have application engineers that can assist your lab.

If you are planning on implementing a laboratory automation system that includes a robotic liquid handler? Contact Retisoft to demo their Genera automation scheduling software.

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