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In addition to personal protective measures, it was diagnostics that mitigated the spread of the Covid-19 virus. During this phase, Promega decided to increase their production of Maxwell cartridges significantly and set a target to be delivered within 12 months. Therefore, they selected Optima as the supplier for their new machine once again. Micro-dosing and high performance are two central features of the new system – and Promega already had a “role model”.
An implementation time of 12 months is quite “optimistic” for a complex, customized diagnostic system – not even the fact that Promega already had a “role model” made it less challenging: Their existing equipment, an OPTIMA Linoline, had to be essentially duplicated. During a pandemic, the additional need for reagents has to be met as quickly as possible.
Promega offers various diagnostic products under the Maxwell brand name. Biological samples, like samples for genetic identity or for research purposes, are analyzed. The Maxwell cartridges, with up to eight cavities, are not stable containers. This requires solutions for automated handling. Extremely small filling quantities, ranging as low as a couple hundred microliters, also creates a challenge. In addition, some of the liquids contain alcohol, which could affect the foil seal.
Last but not least, a special reagent with microbeads is dosed with the OPTIMA Linoline. A dosing unit has to ensure that the original composition of liquid and solid components remains consistently homogeneous within the system. Optima met all of these requirements in a first project based on an OPTIMA Linoline 120. The implementation of the new project, although an almost identical version of the “first edition”, was challenging in terms of time. However, let’s first discuss the system technology …
Correct orientation of the asymmetric Maxwell cartridges is important; these must arrive with the cartridge inverted in the transport system. In the infeed section, after the storage bunker and sorting bowls, the cartridges are guided onto a two-track infeed belt. A combined camera/turning unit recognizes the position of the cartridges and turns them at full line speed to achieve the desired alignment, if necessary.
A blowout station follows the transport rake of the OPTIMA Linoline. At the next station, the cartridges are turned right side up. In this position, the containers are no longer stable, but ready to be filled. In order to transport the cartridges to the filling and sealing station, they are stabilized in their resting position. For all additional processes the cartridges are guided laterally with a specific transport rake system and set down at the weighing positions over format parts.
One of two sorting bowls: The cartridges are placed in an upright position and directed onto a belt.
Still upside down, the cartridges are blown out from below.
The OPTIMA Linoline achieves exact dosing quantities per cavity with 100% in-process control, which directly regulates the control of the integrated peristaltic pumps. A total of 16 peristaltic pumps and 18 load cells are installed for double-lane processing. The empty cartridge is weighed in the first weighing position. After the first fill and the subsequent weighing, the net filling quantity of the first cavity is calculated. This procedure is continued at the other filling positions. Deviations from the target weight of each individual cavity are recognized by the control and, if necessary, immediately corrected, which results in a very high filling accuracy per cavity.
The last cavity in particular, where filling quantities as low as 180 μl are filled with peristaltic pumps, stands out. For comparison: A drop of blood corresponds to approximately 15 to 20 μl. On one hand, the weighing technology is required to measure these low weights precisely in a very short time. On the other hand, the peristaltic pumps must be able to implement the smallest filling quantity corrections of the weighing control.
Dosing the last cavity presents one of the biggest challenges, because the expensive product consists of a liquid and special microbeads mixture. It is essential to maintain the homogeneity of the solid and liquid parts. This challenge was solved in close cooperation with Promega by developing a special recirculation device. The amount of liquid that has not been filled returns to the tank through a hose, connected to the filling needle. In conjunction with a stirring device in the product tank, the original consistency remains unchanged. With this dosing system, Promega benefits from minimized product loss, fewer rejects, and assured product quality.
During the subsequent closure, the film is placed over the entire length of the cartridge and then precisely sealed. It is crucial that all edges of each cavity are completely sealed to prevent the liquids from crosscontamination (for example during transport). These sealing edges also withstand alcohol-based liquids. After sealing, a print is applied to the side of the container and verified by two cameras. An additional print is applied to the foil on top of the container.
Precision is required for two-lane sealing to seal all cavities evenly – all around. At the same time, the quality of the sealing seams has to prevent potential delamination caused by the diagnostics, some of which contain alcohol.
Cameras check the print applied vertically to the cartridges.
Now the cartridges are placed into the trays. However, there may be empty spaces in the transport rake caused by deviations during the inline quality control when cartridges were rejected. Quality samples requested through the HMI during production also can cause gaps. To ensure that every tray is complete, Optima has integrated another sophisticated system: An intermediate shuttle that can be moved to the transport rake. If there are any empty spaces, the intermediate shuttle is aligned accordingly so that there are no gaps after the cartridges have been pushed over. As soon as eight cartridges are lined up, the formation is taken over by a pick & place conveyor and precisely inserted into a tray.
The line processes up to 3,600 cartridges per hour. The system is equipped with a laminar flow from the infeed to the discharge conveyors. In addition to the controlled airflow above the containers, this creates a slight overpressure in the system, which keeps particles out. The OPTIMA Linoline is currently designed for three formats. Optima met the customer’s requested timeline of 12 months, including the installation at the Promega location near Madison (WI) – another result of the successful cooperation between the two companies.
The large tray magazine has space for different tray formats.
Promega is currently processing three formats from the Maxwell series on the OPTIMA Linoline.
For Promega, these are effective systems with high throughput.
"Because of the pandemic, we quickly needed additional capacity to accommodate demand for our Maxwell line," says Promega project manager Sarah Melsen, explaining the background for the third joint project. “Optima guaranteed us a timeline of 12 months from project order to delivery for a ‘copy’ of our first Optima line. Based on the proven partnership, we decided to award the contract to Optima without a proposal request.”
Looking back, the project manager reports: “The first cartridge line gave us the confidence in Optima’s quality and technical ability. The precision and detail given throughout the entire process, from filling to sealing, stands out. Over the course of both projects, the teams from both companies learned how to bridge the differences between countries, cultures and languages, which helped to deliver the second project on time. The same teams that worked on the previous project also completed the new line, resulting in a seamless process and expedited delivery.”
With regard to the operation of the OPTIMA Linoline 120, Melsen names the advantages: “Throughput and the possibility of being able to process many different containers and formats by using size parts. Another benefit is the easy access to the various functional units for the operators due to the machine layout. In addition, we carry out In-Process Controls (IPC) at a very precise level, even with extremely small fill volumes. The user interface, having numerous menu levels, ensures excellent control over all functional units and keeps us informed on all activities.”
Now that three Optima systems are installed at Promega, Melsen is certain that Optima is very competent in all its disciplines and has developed numerous creative solutions to many questions and topics. She says: “For Promega, these are effective systems with high throughput.”
