Microdosing at its finest

Microdosing at its finest

Microdosing at its finest

A range of test formats are used in diagnostics to detect acute infection and prevent the uncontrolled spread of the SARS-CoV-2 pathogen. At the Marburg site, Siemens Healthineers have recently started a very high quality PCR test on an OPTIMA ImmuFill®. This machine achieves high precision reagent dosing into containers from a dosing volume of 50 µl upwards, and these are then closed and labelled.
 

The OPTIMA ImmuFill®'s machine concept has one fundamental advantage – fast delivery times. In the project carried out with Siemens Healthineers, only three months was required to deliver the machine solution, so as to be able to meet the challenges of the pandemic as quickly as possible. Unlike many other suppliers, OPTIMA was in a position to meet this demand.
Part of the ImmuFill® concept is to always have up to three pre-assembled machines in stock at Optima Life Science. This allows the project and customer-specific designs to be completed in the shortest possible time. This idea presupposes that each machine can be built with just a few customized parts. Tobias Schaub, Project Manager for Strategic Projects at Siemens Healthineers, confirms that "delivery time was a definite criterion for the machine."
However, speed alone would not have been enough to win the project with Siemens Healthineers. One of Siemens Healthineers' key requirements was also to have particularly small dosing volumes. The OPTIMA ImmuFill® was originally designed to be used for a filling range from 2 ml upwards. The appearance of Covid-19 and the diagnostics developed for it mean that Optima Life Science was now confronted for the first time ever with dosing volumes starting from 50 µl, a fortieth of the smallest fill volume hitherto available.

Filling system
The OPTIMA ImmuFill® filling system has been comprehensively adapted and optimized by Optima for microdosing from 50 µl.
Straight to the target

So would it be possible to achieve precise microdosing with the existing machine concept? As was the case previously, a solution should work without the articles having to be exited onto weighing scales. In addition, an output of 1,500 pieces per hour would have to be adhered to, even for the smallest filling quantities. This eliminated the option of a tare/gross weight check, which requires the containers to be discharged onto scales, which takes extra time.
The containers have varying weights of +/- 10 mg, which would correspond to a filling accuracy variation of +/-10 µl, so a pure gross weight control would only be feasible for a filling volume of 1 ml or more, reports Jörg Gaukel, Product Manager at Optima Life Science, about the development process. This meant that the only conceivable solution left was to have a reliable, constantly accurate dosing rate, safeguarded by random sampling. This was followed by numerous filling tests with varying parameters, and tubing and peristaltic pump versions were tested in order to finally be able to signal the "go ahead" to the Siemens Healthineers. Delivery within three months "after technical clearance" was agreed upon, because in these turbulent pandemic conditions, it was not yet certain at the start of the project, for example, which type of container would be used in the system.
A filling accuracy of +/- 8 percent was specified in the contract, which today is +/- 3 percent or better in real terms. Accuracy is controlled by random sampling per tray, each containing over 80 containers. If there are any discrepancies, the complete tray is removed and readjusted via the control on the HMI if necessary.

Precision in microdosing
The internal diameter of the tubes was first optimized in tests to achieve very high filling accuracy. Additionally, in cooperation with the manufacturer, care has been taken to ensure that this dimension can be maintained constantly over the length of the tubing. The special tubing, the Y-distributors, the dimensioning and quality of the dosing needle, as well as the peristaltic pump with the optimized number of rolling elements, all contribute to the high filling accuracy. For Siemens Healthineers, this requirement, in addition to the short delivery time, was the second decisive factor in awarding the contract. The aim was to be able to produce the best quality PCR diagnostics.

"The low fill volume was a challenge that has been overcome. However, further details needed to be adapted to fit our requirements, such as the upright transport of the microtubes at the machine outlet," explains Tobias Schaub. Even this technical challenge can be traced back to the low filling volumes. The smaller the filling volume is, the more critical becomes the impact of a missing drop of reagent liquid during the diagnostic procedure. As a result, it was crucial to prevent a drop from being deposited in the container lid or on the inner container wall. Even a small pulse on the container can lead to the undesirable effect. The entire ImmuFill® filling process was designed to be extremely gentle. This is why the closing unit was designed with springs. In the same way, the labeler now uses an electric drive so that no pulses are transmitted to the tube when the label is pressed onto it. Mirror filling, where the filling needle moves parallel or just below or above the liquid level, also prevents uncontrolled splashing in the container.
Last but not least, Jörg Gaukel's team of developers has redesigned the original process away from "bulk-to-bulk" to an upright container outfeed, because if the containers were to tip over, once again there would be a risk that the liquid could be distributed in an uncontrolled manner in the container. The containers' outer shape is identical across all filling volumes, but on the inside the container base varies in height. This means that particularly the small filling volumes present a risk of tipping. The containers are now guided out of the machine via two L-rails at the neck of the tube to ensure upright transportation.

OPTIMA ImmuFill®
Special requirement: The diagnostics are not conveyed out of the system in bulk as they were in the original design for the OPTIMA ImmuFill® but due to the product, in an upright position.
Finally, the tubes are manually loaded into trays. Only the tubes that fail to comply with the quality criteria are ejected via a chute. Torque and correct closure fit, as well as the label's presence, are automatically checked in the process. If any container is left with no contents, an installed gross scale will detect this. These containers are also ejected.
Rotary star
The standard machine has a highly flexible design and requires only a few format parts. A robot transfers the containers and closures and inserts them into the rotary star in a route-optimized fashion.
Built-in Flexibility is Standard

One central characteristic of OPTIMA ImmuFill® is its format flexibility. A key feature of the machine concept is the minimal number of format parts, as generally, diagnostics manufacturers work with a wide range of different bottle types. Siemens Healthineers does not currently utilize this. Tobias Schaub describes the machine as being " very compact and it can be immediately equipped with up to four formats, which also makes it very flexible for future use."   
The sophisticated machine concept also incorporates the expertise of the subsidiary Optima Automation, which has proved to be extremely valuable. The experts in sorting pots and feeding solutions have succeeded, for example, in designing the bottle hopper for bottle formats of up to 125 ml with virtually no format parts. The vibrating bowl for the lids and the vibrating chute are also virtually standardized for all common formats, and only have to be slightly adjusted in the settings when the format is changed. If required, the feed rails can be replaced in just a few simple steps.
One part of this design is a robot that picks up a container and a lid in a single process and inserts them in pairs into a star wheel.
A starwheel itself can in turn accommodate up to four different container and lid formats, so that the principle of low format parts is consistently pursued here too. All other processing stations are arranged on the rotary press. For the machine for Siemens Healthineers, these include filling, closing, labeling and process controls.
For Siemens Healthineers, remote servicing was another "must-have" when they awarded the contract. Especially during the pandemic, remote support quickly proved its worth when travel and on-site appointments were reduced to a minimum. In the early stages after installation and training, when the machine operators at Siemens Healthineers were still becoming familiar with the system, it was possible to answer questions much more quickly by granting online machine access to Optima Life Science. The same is true, for example, for error messages now during ongoing production operation, which can be analyzed, corrected and explained remotely by Optima Life Science.

As well as this, the OPAL (Optima Process Automation Library) software for Siemens Healthineers provides the function of closed-loop batch documentation and efficiency analysis: date, time, batch size, production and downtime, any errors that occur, the number of good and bad products, and more. "The graphic representation helps to present the facts in a simple way," adds Tobias Schaub. Siemens Healthineers always retain an overview.

Less than three months' delivery time

A look at delivery times: In the Siemens Healthineers project, it was clear on June 22, 2020 which containers were to be used, so the "technical clarity" mentioned in the contract had thus been achieved. The factory acceptance test took place at the beginning of September after individual adjustments had been made at the customer's request, such as the upright container discharge. On October 15, the project was completed, including IQ/OQ certifications, site acceptance testing and training at Siemens Healthineers. This means that Optima Life Science has well complied with the agreed delivery deadline of three months. Jörg Gaukel estimates that the advantage in terms of time of pre-production of the OPTIMA ImmuFill® is around six months.
Tobias Schaub describes the running of the project as very cooperative and result-oriented. "Any technical issues that came up in the meantime were discussed together and quickly resolved. This project was a positive experience for everyone involved," he concluded.

Vibratory bowl
A vibratory bowl for all kinds of closures. The integrated infeed solutions also span an extremely wide format range, with virtually no extra format parts required.

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