The use of rapid tests has grown enormously in recent years, not least due to the corona pandemic. The one-time tests have evolved in terms of lateral flow and result accuracy. However, the test kits, especially the housing shape, have remained pretty much the same. This gave rise to the idea of a platform solution for diagnostic tests that uses as little material as possible and can be implemented for different types of evidence. Miss Dr. Tina Hassberg initiated a new and more sustainable development by founding Solios Diagnostics and with the patent for RapidoDX, an all-in-one plattform for lateral flow immuno assays.
A design for manufacturing approach for later scalability
When the project started, a first draft was already available. A detailed analysis using a digital twin revealed initial problems for the later implementation into series production. The Sanner engineering team then carried out various component optimizations, including wall thickness adjustments, draft angles and the thread were adjusted. Investigations regarding the operating forces were carried out and in particular the position and degree of bending of the test strip were adjusted to ensure optimal lateral flow.
Virtual prototyping saves time and money
The biggest advantage of digital twins is the time and cost savings: thanks to the simulation of tools with different plastic materials, it is possible to quickly define which material is most suitable for a specific item in terms of processability and which part design ensures the item's funtionality. Tool changes and optimizations can be checked virtually in advance. This saves time-consuming material testing and time for test runs on injection molding machines. Any problems that may arise, such as air pockets or difficulties with shrinkage and distortion, can be identified and corrected using the digital twin before the actual tools go into production. Thanks to the permanent virtual optimization of the tool design, compliant, high-quality parts can be reliably produced.
The simulation is also worthwhile from an economic and ecological perspective: The digital twin shows where cycle times and materials can be reduced - which in turn has a positive effect on the environmental balance: products become more sustainable and material waste is reduced. Used correctly, simulation leads to a significantly lower error rate. It avoids expensive and time-consuming tool corrections, results in faster sampling with less rejects and waste, and supports a shorter time to market and more efficient production with better cycle times.
Rapid prototyping for handling tests
The first 3D printed samples to test handling and optics were produced in the Sanner technical center using so-called SLA printing (stereolithography), a 3D printing process. This is particularly suitable for medical technology applications, as biocompatible materials in accordance with DIN ISO 10993 can also be processed here. The materials used by Sanner have similar, although not identical, mechanical properties compared to conventional polyolefins. This simplifies the checking of various product properties. More complex parts in particular can be used for optical and tactile measurement. The development of processes and assembly concepts can be planned better, which significantly accelerates this development step. Prototypes can sometimes be manufactured and tested within a day.
Aluminum sample tool for the first small series
After the 3D printed samples produced the desired result, the next step was to transfer the design to an aluminum tool to obtain samples made from traditional polyolefins for further testing. To do this, the prototypes must have exactly the same functionalities as the final product in order not to distort the results of the study.
The next step: implementation with a bio-based plastic
A used diagnostic kit must be disposed of in the trash as required by law as it may contain contaminated material. When it ends up having to be burned for safety reasons, CO2 is released. Therefore, for better sustainability, it should consist of as little material as possible and ideally bio-based plastic made from renewable raw materials. The implementation of the device in bio-based plastic is currently being tested at Sanner.