By replacing a fifteen-year-old well plate filling machine, a laboratory increased throughput yields by a factor of eight and cut waste by half.

Well plates are the multi-well trays used for high-throughput screening of in vitro devices (IVD) in clinical laboratories. Reproducibility, precision, and accuracy are fundamental for creating stable conditions for clinicians to interpret sample test results. Basically, well plate equipment users need dependable innovative solutions to deliver high volume and accurate filling of assay containers.

A leading provider for disease and allergy diagnostic assay kits decided on a novel approach when upgrading its existing system. After fifteen years in service the machine was slow, inefficient, inflexible, and sometimes delivering only 600 plates a day.

Moreover, spare parts were becoming a problem, leading to unscheduled downtimes. Also, the lack of automated plate stacking meant it needed extra manual operation. The company decided a bespoke system was the answer. Mitsubishi Electric System integrator Horizon Instruments applied their scientific and engineering experience to the challenge.

Accurate well plate filling

The well plate filling machine revolves around four Mitsubishi Electric MELSERVO-JE servo motors and their associated servo amplifiers. A high-speed, noise immune SSCNET III/H fibre-based network provides the connections. It loads empty well plates from a stack (input station) onto a walking beam transfer system that moves towards the filling station. There, the plate aligns with a movable nozzle head that connects each of the 96 wells with a filling nozzle. The latter receive the measured volume of liquid from a specific input bottle.

The system communicates with a GOT 2000 HMI, through which operators select the recipes and track the process in real-time. Once the liquid dispensing is complete, the plates move to the output station for automatic stacking.

A Mitsubishi MELSEC-L Series PLC controls the motion during these operations to ensure accurate speed and positioning. Furthermore, the  L-Series is a compact and flexible solution that can control different networked stations.

Using the HMI, the operator selects the recipe and the liquid volume for dispensing into the wells (<250µl) and monitors the process in real time. Additionally, if the system stops the HMI provides diagnostics to help the operator resolve the issue and restart the machine.

PLC integration

The seamless integration of Mitsubishi Electric PLC, servo motors and servo amplifiers ensures the machine performs as expected. The new machine delivered fast and accurate filling speeds, repeatability, and precision.

By eliminating overfilling, the IVD kit manufacturer reduced the downtime needed to clean the machine and its surroundings. Product quality improved and the factory expects to reduce waste generation by over 50%.

The new machine can process up to 5000 plates a day. This is eight times higher than the old system, even when it was working at full capacity.