Liquid handling robots transfer liquids based on programming and inputs from a user, integrated sensors, or external data sources. Robot liquid handlers transfer liquids using multiple technologies that are ideal for the liquid’s properties and volume being transferred. There are multiple things to consider when adding liquid handlers into a laboratory workflow.
Liquid Handling Robot Definitions
Wikipedia’s liquid handling robot definition
However, the problem with wikipedia’s definition, is that it requires readers to know what a robot is.
Rave Robot’s liquid handling robot definition
A liquid handling robot transfers liquids based on programming and inputs from a user, integrated sensors, or external data sources.
All liquid handling robots have the following:
- The capability to transfer liquid from a source to a destination
- The ability to respond to set of commands based on input from at least one of the following sources
- user commands
- integrated sensors
- data retrieved from some other source (ie a csv file or database)
In other words, an automated liquid handler must have the capability of performing variable actions based on inputs. Otherwise, it is not a robot.
Why bother to use a liquid handling robot?
There are 5 basic reasons to use a liquid handling robot in the lab:
- Speed
- Precision and accuracy
- Reproducibility
- Recorded log of all liquid handling actions
- Robots don’t need sleep
Speed: tortoise vs. the hare
A common fallacy is that the average liquid handlers is faster than a scientist with a pipette. In reality, liquid handling robots take significant time to set up and break down. Liquid handling robots are only faster when there are enough samples to account for setup and breakdown time.
Speed can be a good reason to use a liquid handling robot. However it is more in the sense of the tortoise and the hare. Speed is almost never the only reason to use a liquid handling robot; it is also rarely the most important reason.
Precision and Accuracy
A well calibrated, liquid handling robot is both highly precise and accurate. This is because liquid handlers use a set of liquid handling instructions that are based on the following:
- properties of the liquid being handled
- volume being transferred
- special transfer needs to maximize precision and accuracy.
A few examples of the liquid handling instructions provided in liquid classes, include:
- location of aspiration within source well (distance below surface, etc)
- pipet tip pre-wetting needs
- aspiration rate
- dispense locations (into air, into liquids, onto surface, etc).
- dispense rate
- pre and post aspirate volumes for blowout and droplet control
Reproducibility
The ability to treat liquids differently based on liquid classes means that systems use the best practices for transfers. Therefore, the error rate and variability of each transfer can be known. This is true for 1st sample transferred or the 1,000th sample.
Liquid handing robots always follow the rules set for them in the liquid classes. Occasionally, some robots even have the ability to use error handling, if the rules can’t be followed. This means that all liquid transfers are both reproducible and optimizable.
Recorded log of all liquid handling actions
In my opinion, the recorded log is the most valuable reason to start using a liquid handling robot. All liquid handler actions are recorded in a log file that anyone can access; Therefore, if you want to investigate a result it is all there to see.
If the system made an error during the run, that error was recorded. While I’ve had the pleasure of working with scientists with great hands; I’ve never seen them record the amount of detail a liquid handling robot does.
Robots don’t need sleep
Manual liquid handling has multiple challenges for scientists as sample numbers increase. This includes repetitive stress injuries like carpal tunnel syndrome. It also includes increasing error rates as a scientist’s eyes and hands get fatigued.
Liquid handling robots eliminate both issues.
The least utilized liquid handling robot capability is running them when scientists are not in the lab. Methods can be started to have the liquid handling completed by the time a scientist shows up in the lab. Or sample handling and applying human readable labels can begin after a scientist goes home for the evening.
Robots don’t need to sleep, and this means that scientists can.
How do robots handle liquids?
Liquid handling robots usually use one of the following methods aspirate and dispense liquids:
- Acoustic droplet ejection (ADE)
- Positive displacement
- Air displacement
- Liquid displacement
- Peristaltic pump
Most liquid handlers leverage one of the above methods with the capability to perform multiple parallel liquid handling processes simultaneously. Some liquid handling robots use multiple channel arm (MCA) to be able to transfer 96 or 384 identical volumes.
Acoustic droplet ejection:
Acoustic droplet ejection utilizes acoustic energy to transfer liquid droplets from a source well to a destination plate. Liquid droplet volume ranges from 1-50 nL and precisely controlled by modifying the frequency of the acoustic energy used. ADE transfers volumes as large as a few microliters by ejecting multiple droplets to the same destination. ADE is a touch-less technology because transfer does use pipet tips. While ADE doesn’t require pipet tips, it does require specialized transfer plates.
There are two companies that currently make ADE liquid handling robots. Labcyte Inc is the larger and better known of the two companies. Labcyte was purchased by Beckman Coulter in 2019.
- EDC Biosystems
- ATS Gen5
- Labcyte Inc: Acquired by Beckman Coulter in 2019
- Echo 650 series
Positive displacement
Positive displacement liquid handlers use specialized pipet tips with pistons that transfer volume ranges of 25 nL – 5 uL. The only company I am aware of that produces positive displacement liquid handling robots is SPT Lab Tech. They make two base models:
- Mosquito: 25 nL – 1.2 uL
- Dragonfly: 200 nL – 4 mL
Air displacement
Air displacement automated liquid handling typically utilizes syringes filled with air to aspirated and dispense liquids. These systems tend to have multiple syringes that can all be controlled simultaneously in parallel. The best air displacement liquid handling robots include real time pressure feedback that assure a closed system.
The Hamilton MicroLab Star pictured at the bottom of this page is one of many air displacement liquid handling robots.
Liquid Displacement
Liquid displacement liquid handling robots use syringes filled with system liquid. The system liquid is displaced by a syringe to transfer liquids. There is an air bubble that separates transferred liquid from system liquid. These systems tend to have multiple syringes that can all be controlled simultaneously in parallel.
The Tecan Freedom EVO pictured at the bottom of this page is an example of a liquid displacement robot. Most liquid handlers have been transitioning to air displacement in newer models, with liquid displacement becoming less common.
Peristaltic Pumps
Peristaltic pumps have been the manual liquid handling tool of choice for decades. They are finally making their way into liquid handling robotics. Peristaltic pumps have the ability to precisely control flow rates and liquid transferred across a large range of volumes. At this time, there is only one fully integrated liquid handling robot with peristaltic pumps on the market. The REVO buffer prep robot uses peristaltic pumps to prepare buffers that are up to 2 L in volume.
DIY automation engineers are also creating peristaltic pump robots. They are pairing them with scales and pressure gauges to create robotic systems for larger scale liquid handling needs.
What liquid handling robot is best for my lab?
A liquid handling robot should be selected based on the liquid handling needs of the lab. These needs includes:
- volumes handled
- types of sample manipulation required
- throughput requirements
- precision and accuracy needs of the liquid handling
In addition, you should consider how this robot will be integrated with other functions within the lab or external labs. What sort of containment is necessary for this system? Hold a meeting with scientists in the labs that are providing the liquid samples that will be handled.
Talk to the scientists who will be using samples generated by the robot. And then select liquid handling robots with the capabilities that match up with your workflows. You should rate your list of systems based on their match to your needs. However, try to be flexible, because the final selection has a variable human component.
The best robot is the one that has human resources to support it.
Selection of a liquid handling robot based on the specific need is necessary. However, it is only valuable if there are resources available to program, troubleshoot and maintain the robot.
In reality, the robot in your lab needs access to the human resources required to support its function. I routinely see robots purchased only to become extremely expensive paperweights due to a lack of methods or support.
Ask questions about what internal expertise and support there is for the system. This means that human resources may end up driving selection of the system. This can be true even is two labs have identical sample handling needs, but different human resources to support them. The application specialist supporting your automation is the limiting reagent for your experiments, not the systems themselves.
RaveRobot’s preferred liquid handling robots
Below is the short list of liquid handling robots we have extensive experience with and have written articles about. If you want to see our larger list of liquid handling robots, checkout our liquid handling robot list.
Hamilton MicroLab Star
Description:
- Volume range: 0.5 uL – 1 mL
- Variable Liquid handling: 8-16 channels
- Pipetting technology: Air displacement
- Multi-channel arm: 96 or 384 well head
- Plate movement: 2 channels with pads or iSWAP
- Deck Sizes: STARlet, STAR, STAR+
- Scripting language: Venus
Articles:
What To Do With All My Data? A Primer on Hamilton STAR Data Handling
10 Tips for Writing Methods on a Hamilton STAR You Might Not Know
How to Choose a Liquid Handler for Sterile Cell Culture
Adding a 3D Model to Your Hamilton Star Deck Layout
How to write a hitpick method in hamilton venus/
Automated Bioreactors and Cell Culture List
Manufacturer Link:
Tecan Freedom EVO Series
Description:
- Volume range: 0.5 uL – 1 mL
- Variable Liquid handling: 8 or 16 channels
- Pipetting technology: Liquid displacement
- Multi-channel arm: 96 or 384 well head
- Plate movement: Robotic Manipulator Arm (RoMa)
- Deck Sizes: 75, 100, 150, 200
- Scripting language: EVOware
Articles
Fix Some Unexplained Tecan Freedom EVO System Stops
Fix Tip is Broken Error in Tecan EVOware for Tecan EVO Robot
Q&A: How to Export and Import Scripts for Tecan EVOware
Protein Purification Robot List
Manufacturer Link:
Want to see other types of liquid handling robots? If so, follow the link to our Liquid Handling Robot List.
If you are interested in specialized liquid handling robots, please visit our cell culture or protein purification lists. We also have an article about How to Choose a Liquid Handler for Sterile Cell Culture.
Visit our other liquid handling robot links
Liquid Handling Robot Introduction and List
How to Choose a Liquid Handler for Sterile Cell Culture?
Protein Purification Robot List
Automated Bioreactors and Cell Culture List
Check out Rave Robot’s List page for other lab automation equipment lists. In addition, you can visit our home page for more of our content.
