Productivity boosted by a factor of 8 through automation venture

Well plates are utilised by clinical laboratories where bioassays are used for high-throughput screening and IVD. In these situations, reproducibility, precision and accuracy are fundamental to create a stable and reliable system that allows clinicians to correctly interpret the results. In this case, an existing unit had been in service for 15 years and had recently started experiencing a number of issues that were affecting productivity and efficiency. The system was prone to overfilling the wells, causing liquid spillage and at one point the manufacturer could only fill half of the 96 wells within one plate at once. As a result, the process was substantially slowed down and could only deliver 600 plates per day.

The technology behind it was also obsolete and several replacement parts were no longer available off the shelf, leaving the factory exposed in case of equipment failure. In addition, the system could no longer offer the level of flexibility that the plate-based assay provider needed to support its customers and the unit did not offer plate stacking, which was done manually. Within a plate, it could only fill all 96 wells with the same liquid, without offering the possibility to accurately dispense different substances onto one plate. To develop a new, bespoke device, the company contacted instrumentation and automation design and manufacturers Horizon Instruments, who then turned to its preferred process automation vendor, Mitsubishi Electric, to source key automation components to plan an effective system together.

Reliable, robust and cost-competitive

Daniel Bolton, Technical Director at Horizon Instruments, comments: "We were keen to use Mitsubishi Electric's range of automation products as we always find them to be very reliable, robust and cost-competitive. The company also has a good level of stock, which supports quick turnaround times and we appreciate its responsive and expert customer service. Not many businesses in our opinion - including other large, global enterprises - are able to offer the same level of servic".

The new well plate-filling machine uses four of Mitsubishi Electric's MELSERVO-JE servo motors with associated servo amplifiers, connected via a high-speed, noise-immune SSCNET III/H fibre-based network. These load empty well plates from a stack (input station) onto a walking beam transfer system, which moves towards the filling station. There, the plate is aligned with a movable nozzle head that connects each of the 96 wells with a filling nozzle. The latter receive the necessary volume of liquid from a specific input bottle. Once liquid dispensing is complete, the plates are transported to the output station and safely stacked on top of each other.

The motion performed during these different operations is controlled by Mitsubishi Electric's MELSEC-L series PLC to ensure accurate speed and positioning. This is a compact and flexible option that can control different networked stations. Jeremy Shinton, Modular PLC Product Manager at Mitsubishi Electric, explains: "We chose the L series PLC because it could effectively handle the high level of complexity that characterises the current application as well as support any expansion of the unit in the futur". The system also communicates with a GOT 2000 HMI, through which operators can select the correct recipes and the liquid volume that should be dispensed into the wells (this ranges between 0 and 250uL) as well as monitor the process in real time. If the system stops, the HMI also provides key information to help operators resolve the issue and restart the machine as quickly as possible.

The integration of PLC, servo motors and servo amplifiers ensured a fast filling speed and high accuracy together with repeatability and precision, despite the low volumes being processed. As a result, the IVD kit manufacturer could eliminate all the issues associated with overfilling, such as equipment downtime to clean the machine and its surroundings, whilst improving the overall product quality. In particular, the factory expects to reduce waste generation by over 50 per cent. In addition, the manufacturer improved productivity. The new machine can now process between 4,000 and 5,000 plates per day, a volume that is 7-8 times higher than the existing system even when it was working at full capacity. Further, the set-up created by Mitsubishi Electric and Horizon Instruments is flexible enough to scale up and support future implementations. For example, it is possible to install robotic arms that can load and unload stacks of well plates or collect samples for quality control purposes.

Learn more at gb3a.mitsubishielectric.com.