Automation has been defined as the use of control systems to reduce the need for human work in the production of goods and services. In the realm of biomedical research or clinical testing, automation often involves processing liquid-based analytical tests. Automated biological testing can take on many forms, ranging from individual instruments performing a single task to large, room-sized, custom-robotic systems capable of automating very complex tasks. In between these two extremes are simple modular automated systems designed to automate a select series of tasks necessary for a specific assay technology, such as enzyme-linked immunosorbent assays (ELISA).
ELISA is one of the most widely used assay formats in biomedical research. Numerous clinical, veterinary and research assays use the specificity of antibodies, typically in pairs, to quantify a diverse array of analytes from different sample matrices. Despite the analyte diversity, the general ELISA process is constant. With a typical ELISA protocol, several cycles of washing microplates, adding reagents and incubating are repeated to elicit the chemistries and remove unbound material before data collection. Numerous repetitive steps in manual ELISA and other standard laboratory assays make the process extremely time-consuming, requiring lab technicians and scientists to spend time on pipetting, washing and dispensing steps as well as on feeding plates into an automated reader for analysis. By incorporating specific instruments such as microplate washers, dispensers, readers, automated pipettors and more, the assays are easier to accomplish. By linking two or more individual operations with simple automation, one may now accomplish all or part of the overall workflow with less time and labor than are required by manual methods. Here we describe a simple modular automated system that employs three microplate-based instruments linked with a plate mover to shuttle microplates as required for the ELISA process.
The robotic system used an Orbitor™ RS microplate mover from Thermo Fisher Scientific (Burlington, Ontario, Canada) to move microplates to and from each station. A 405™ TS microplate washer and a MultiFlo™ microplate dispenser from BioTek Instruments (Winooski, VT) were used to perform assay washing and reagent dispensing, respectively. Ambient temperature incubations were carried out using the random-access plate hotels of the Orbitor RS system, and absorbance measurements were made using an Eon™ microplate spectrophotometer from BioTek Instruments. The robotic system was configured on a standard two-sided lab bench. The fully configured system had a footprint of 60 x 32 inches (Figure 1). While an open bench end was used, the low height (29 inches) allows the plate mover to be used under many commonly used center-bench shelving units. A mezzanine table from Thermo Fisher Scientific was used to support the 405 TS and MultiFlo. The table unit provides upper and lower shelves capable of supporting multiple instruments. The top shelf is configured on sliding rails, while the bottom shelf pivots outward, allowing easy access to the instruments for offline use or maintenance.
Figure 1: Rendered graphic and actual modular robotic system.
Using an HIV1/2 ELISA kit from Avioq, Inc. (Research Triangle Park, NC), we compared the results of the automated and manual methods. Positive and negative absorbance controls were compared, as were pooled serum samples from separate batches, and they demonstrated very similar mean values that meet the kit validation criteria (Figure 2) between manual and automated assays. Comparison of the %CVs show that the automated system exhibits slightly less variation than the manual batch (Figure 3). As demonstrated in Figure 4, the plate-to-plate variation is minimal, suggesting that the results from several plates within a run can be compared against one another. These data indicate that this simple modular automated system may be employed to process ELISA that have ambient incubations and require four reagents or fewer. Additional instrumentation, such as a temperature-controlled plate hotel, would expand the assay menu.
Figure 2: Comparison of manual and automated assay formats. Batch runs of the Avioq HIV-1 assay were performed manually (three plates) or in two separate runs using the automated Orbitor RS ELISA workstation (five plates each). Data represent the mean and standard deviations of all the data points for each batch experiment.
Figure 3: Intra-assay precision comparing manual to automated procedures. %CV of the positive control (PC), negative control (NC) and pooled serum samples were calculated for individual plates. Data indicates the mean %CV for each assay run.
Figure 4: . Repeatability of the Automated Avioq HIV-1 Microelisa Assay. Dilutions of the positive control (PC) along with the negative control (NC), pooled human serum and pooled human plasma were assayed in replicates of eight on four separate microplates. Data represent the mean and standard deviations of each microplate.
There are a number of advantages to simple modular automated systems when compared to manual or large, integrated systems. The most obvious advantage is the ability to do more research in less time, also referred to as an increase in throughput. Lab managers are increasingly tasked with increasing throughput in less time and using a leaner operation. In nonautomated laboratories, increased throughput is managed through increased individual productivity or increased full-time employees (FTEs). Instruments increase throughput somewhat, but typically these instruments are used only during normal operating hours, so the net operational or throughput gain may not be as large as expected, while requiring more precious bench space. Adding a small benchtop automation module to link two or more instruments increases overall throughput without increasing FTEs. An operator is required to set up and start an automated system, but once it is operational the system runs unattended, allowing scientists more time to take on additional value-added tasks such as data analysis, interpretation and reporting.
Furthermore, individual instrument usage can be maximized because automation provides just-in-time plate delivery. A technician does not need to feed an instrument on a regular basis, so labs where employees are already multitasking while regularly feeding an instrument are no longer subject to slippage. Additional throughput is garnished through unattended overnight or off-shift runs. Automation typically provides better sample consistency, assay control and uniform processing, resulting in increased data quality. Full automation can improve assay data quality by eliminating the operator variability that exists in manual methods. For example, liquid handling parameters such as volumes, aspiration and dispense speeds and heights, mixing speeds, and cycle number are set during automated method development; therefore, there is no variability from plate to plate. Additionally, strict plate incubation times are defined during method development. By controlling these variables within plate, intra-assay (between plates in the same batch) and inter-assay (batches separated in time) runs, variability is significantly reduced through automation.
Automation provides the means to monitor assay operations that are difficult or impossible to track with manual operations. Standard questions—such as When was it run? What were the conditions? Who ran it? Were any issues noted?—are all tracked automatically. The operations performed on specific samples or plates are date and time stamped and can be audited at a later date. Automated systems also can provide remote feedback during operation by sending e-mails, text messages or pages to notify users of the system status. Lab managers can quickly and easily review the passage of all assay plates to determine if any spurious operation times or conditions were reported.
Simple modular automated systems also improve laboratory safety. Automating repetitive ELISA tasks decreases repetitive strain injuries associated with manual pipetting. Lab personnel have less exposure to hazardous chemicals and biologicals, and waste may be directed to specific locations without spill or exposure risk. For example, liquid waste from plate washers, serial dilutions and more are collected in waste bottles, which can be electronically monitored to notify the technician when it is time to empty them. Small modular systems can be placed to interact with fume hoods or biological safety cabinets or can be provided with their own environmental enclosure to protect staff.
Gone are the days of having a large multipurpose automated system—instead, with smaller modular benchtop automation like Thermo Scientific’s Orbitor RS and Orbitor BenchTrak™, one can create automated workstations for partial or complete workflows. The overall investment required by large stand-alone automated systems consisting of four or more instruments (7 to15 instruments on average) typically meant that they were the domain of large pharmaceutical companies or, more rarely, academic core facilities. The flexibility and size of small modular systems provide distinct advantages over larger multipurpose automated systems. Modular systems are easily reconfigured to address the ever-changing assay needs of today’s laboratory. Each instrument is a discrete entity that can be removed and replaced with a different device. For example, the plate washer could be replaced with a pipetting device if a wash step is no longer required but a sample dilution step has been added to the process.
Modular systems can be configured for optimal assay performance. Modular systems employ one or more stand-alone instruments designed to perform specific tasks; as such, they are capable of outperforming many large integrated systems. In regular use, microplates are loaded onto each instrument and processed. Processed plates are removed, and another plate is loaded onto the instrument. As each instrument is designed for a specific task, performance is optimized, whereas with an all-in-one system, performance compromises are often made as a result of design considerations. Modularity also simplifies repair and serviceability of the automated system. Routine maintenance can be performed on individual stand-alone modules while allowing the rest of the system to continue operation. In the case of hardware failure, the loss of a subsystem with many large integrated systems results in the entire system being inoperable until a field technician can arrive, diagnose the problem and make the repairs. Modular systems need to have only the failed module swapped with a functional unit, which can be shipped complete.
Small, simple and modular automated systems efficiently use laboratory space. While modular systems can be configured to have numerous devices, many contain only a few instruments that do not require much space. Standard lab counters are usually sufficient to support the system, while integrated systems are larger than a standard lab bench and require special tables to accommodate their size. Relative to the larger systems, benchtop automation modules are focused toward the end user by enabling quick and easy reconfiguration, redeployment and repurposing to meet changing needs. Instruments can be readily swapped in and out of the automated workstation and may also be used offline to maximize their overall usage.
While ELISA was used as an example, many analytical technologies used in biomedical research and clinical assays are amenable to automation in microplate format. The standardized 96-, 384- and 1,536-well format of microplates provides the means to automate many tasks. Typical workflow processes done by these small automations include sample preparation, ELISA, nucleic acid and protein purification, cell or biochemical assays, cell maintenance, qPCR and nextgeneration sequencing.