Automated liquid handling (ALH) grew from the highthroughput needs of medical diagnostic labs in the late 1980s through the 1990s and then received an additional boost from genomic sequencing. As it evolved from a specialized, expert-driven instrument system to a generalized laboratory workstation, ALH has become more accessible to more workers in more labs.
Automation vendors have achieved this despite the uniqueness of ALH workflows. ALH is not a point and shoot technique like spectroscopy or analytical chromatography. Every ALH experiment is unique in terms of reagents, volumes, order of addition, target analyte, and readout.
Speed is the most-cited advantage of ALH compared with manual pipetting, but as we will see, pipetting accuracy and freeing lab workers from monotonous pipetting are valued at least as highly as throughput. Depending on the number of samples a lab typically runs, the business case for acquiring or upgrading an ALH system may be based on throughput, quality, operator time savings, or some combination of the these factors.
Accuracy provides an additional, independent cost-saving benefit. ALH can ensure the accuracy of ultra-small volume dispensing, which is a principal factor in minimizing assay, reagent, and disposal costs. Microliter-size assays are now routine, with PCR often employing nanoliter or picoliter reaction volumes and microarraying striving for femtoliter dispensing. Reduced volumes increase an assay’s volumetric complexity, which in turn raises the standard for accurate pipetting.
Assay miniaturization has spilled over into instruments and components as well. “Lab space is limited, and the less space taken up by instrumentation, the better,” says Merja Mehto, product manager for automated liquid handling products at Thermo Fisher Scientific (Vantaa, Finland). This has led vendors to devote significant design resources to creating liquid handlers that are scalable, compact, and easy to use.
Automated Liquid Handling Workstation VERSA 10 | Aurora Instruments www.aurora-instr.com
Given that every liquid handling workflow is distinctive, the greatest challenge facing the ALH industry is providing “average” laboratories with customization at a reasonable cost. (As one unnamed vendor confided, “Customers want everything.”) Vendors achieve customization through standardization of consumables and reagents and in investments in instrument interoperability.
OEMs also provide validation packages for instruments and reagent kits, greatly reducing this tedious process in users’ workflows, notes Sikander Gill, Ph.D., of Aurora Biomed (Vancouver, BC). “This enables customers to purchase both the application and the solution, while vendors benefit from continued sales of consumables.” The evolved product mix may result, he says, from “OEM partnerships” or through diversification of research and development teams within the equipment company
Some experts would argue that software and interfaces have been the most significant areas of change for scientific instrumentation. “ALH software needs to keep pace with customer needs,” says Gill, by providing ready access to “complex assay and integration” capabilities through a user-friendly interface.
Advances in computing and data storage began in earnest with Microsoft DOS. Microsoft Windows® provided a glimpse into the possibilities of graphical user interfaces (GUIs), particularly for “distributed” workstations such as liquid handlers that may be connected to several other instruments. But even with graphical interfaces, users faced system-level involvement in programming and engineering.
“We were conditioned to accept a situation that wasn’t quite perfect,” says Tom Osborne, product manager at PerkinElmer (Waltham, MA).
Automated Homogenizer Liquid Handling System | LH96 Omni International | www.omni-inc.com
Thought leaders at research centers still interact with instrumentation in this manner, but the underlying philosophy of instrument control is changing. This isn’t because instrument experts are disappearing from universities (even as their numbers dwindle at companies); it’s due to a shift in user expectations: end users and their employers increasingly stress walk-up operation and short learning curves, and vendors comply.
Younger scientists raised on electronic gadgets, portability, interconnectivity, and out-of-the-box usability are pushing the boundaries of software and interface expectations even further. “Vendors need to invest in GUIs that are more ‘purpose built’ for walk-up utility for mainstream audiences who are interested in answering scientific questions in 12 minutes, not in method development or engineering,” Osborne comments. “At this stage all the major vendors are passionate about this.”
According to Greg Robinson, director of automation products at Gilson (Middleton, WI), vendors dedicate significant effort to software and interfaces, specifically so that:
- Overall robustness prevents crashes.
- Drag-and-drop functionality creates methods more rapidly and reliably.
- Interactive, dynamic task pages update automatically based on the user’s selection; for example, hiding or uncovering certain fields in context, depending on the selection. Pages should display only the required entry boxes and selections. This improves software usability, reduces mistakes, and ultimately increases the efficiency of method development.
- The ability to automatically optimize the application or protocol effectively reduces instrument wait time.
- They allow interaction with peripheral devices such as balances, bar code readers, chillers, heaters, pH meters, shakers, and anything else that affects the workflow.
- Manual controls (related to simulation) allow users to perform base-level functions such as priming solvent lines and troubleshooting error conditions or application issues.
- Simulation. Users require modeling capabilities to test methods visually on a computer screen before actually running the instrument and wasting reagents and precious samples, etc. This advanced feature allows users to spot any issues that may negatively affect either the experiment or the instrument.
“Users want a system where they can push a button and leave,” says Tom Osborne, “but one that is flexible enough to incorporate changes in method or workflow.” This level of trust in a complex instrument with many moving parts is difficult to achieve without some sort of simulation function.
Expanding beyond traditional reagent- and solventdispensing markets is a sign that ALH is maturing as an industry. Cell-based assays, a high-growth area for microtiter plates and by extension ALH systems, are an exciting area for innovative liquid handling on a small scale. Cell-based assays are used to screen drugs, cosmetics, and chemicals of environmental concern, as well as to test cells themselves for viability, productivity, or bioremediation worthiness. As with other types of assays, test volumes are reaching microscopic proportions, with many vendors selling highdensity (up to 1,536-well) plates with microliter working volumes suitable for cell work. BioFluidix claims single-cell delivery capability, for example, for its PipeJet.
Multipurpose Liquid-Handling Instrument VIAFILL™ | INTEGRA | www.integra-biosciences.com
Microplate Pipetting System | Precision™ | BioTek | www.biotek.com
Automation provides consistency for cell-based assays, but conventional wells do not reproduce physiologic conditions very well because the cultures are two-dimensional. Cells in nature exist in a complex three-dimensional matrix, not in solution. At the 3D Cell Culture conference (part of the huge Dechema exhibition series) held in February 2012, 3D Biomatrix (Ann Arbor, MI) introduced “Hanging Drop” cell culture plates in which cell volumes are maintained as suspended droplets accessible from either the top or bottom by conventional liquid handling equipment. Shortly after depositing the droplets, cells form physiologically relevant “spheroids,” which may be tested by drugs or reagents.
Speed is also an issue with cell-based assays. Completing the protocol before resident cells have the opportunity to change through growth, senescence, or death is critical for obtaining consistent results. Another source of inconsistency with living systems is degradation of assay reagents such as proteins, enzymes, or genes. Technicians tend to overuse prepared samples and reagents when time runs short. Speeding up the process reduces this tendency.