This is the technical project description of the TUM techchallenge to target the shortage of plastic consumables for COVID-19 PCR tests.

1. About us
2. Brief Introduction and our Solution Approach
3. Materials and Methods
4. Discussion and Outlook

We are a team of 4 highly motivated students and have known each other for over 3 years. We have diverse backgrounds in technology (electrical/mechanical engineering & computer science) and management (TUM-BWL). We joint our forces to help to overcome the shortages of plastic consumables for PCR tests in Ghana.

The coronavirus pandemic is an ongoing pandemic caused by the COVID-19 disease (for more information to the pandemic we refer to wikipedia). In order to control this pandemic by disrupting infection chains, PCR tests have been one of the most essential tools so far. Extensive PCR testing by many countries has lead to shortages and price increases for testing equipment. Since first world countries have a higher market power and more money to spend compared to third world countries, this development has hit third world countries disproportional more than first world countries. In particular, third world countries are struggling to get access to plastic consumables for PCR tests on the world market. These are swabs, tubes, pipette tips, and spin columns.

To dampen the effects of supply shortages of such consumables, we have developed a mobile production table which is capable of producing these consumables within the testing laboratories. Our production plant is optimized to be simply deployable to laboratories in third world countries, to be operable by a low amount of labor, and only requires a minimum amount of training to be operated.

Our production setup consist of 4 steps: 3D printing, isopropyl bath, UV cure, and Packaging. Short descriptions of every steps are found in the figure below.

The table we provide consists of 4 3D printers from the company Anycubic, one isopropyl bath, and an UV chamber. The costs for one table are shown in the figure below.

The total cost of one such table is about 1000€.

As a printer, we use the Photon S from Anycubic.

To print the plastic consumables, first the CAD files are needed. These are found here. The CAD model of the consumables have to fit perfectly to the laboratory equipment. Since some laboratories use slightly different equipment, eventually some of the models have to be adapted if other laboratories want to use them too. Once the model is adapted, it has to be sliced and converted to a file which is compatible with the 3D printer. For the printer we use, this is a ".pw0" file. A detailed description of how to slice the files is found here. Afterwards, the printing can be started.

For the printing we use the surgical guide resin from Formlabs for the swabs and the Anycubic transparent 3D printer resin from Anycubic for the other parts.

Post processing plays a very important role in SLA printing. It augments the surface quality of the parts, cleans excess resin off and hardens the part. Post processing can be divided into 2 steps: Isopropyl bath and UV Curing.

Right after a SLA print the surface of the parts is coated with a layer of liquid resin. An isopropyl bath for an approximate 30 minute duration, helps to get this resin off. After the isopropyl bath follows the UV curing.

UV curing hardens the parts and lets them achieve their optimal mechanical properties. Our custom designed UV curing station consists of an aluminum garbage can, 2 UV lamps and a glass plate. The UV lamps emit light with a wavelength of 405nm. After removing the parts from the isopropyl bath, they are placed on the glass plate, which in turn is positioned at the bottom of the garbage can. After 30 minutes under UV light, the parts can be removed and used for their required function.

Since our production happens within the laboratory, for consumables which are used within a small amount of time, packaging is not required. However, this requires a good logistics by the operators of the laboratory. For equipment which should be stored, or should be delivered to other places (which is necessary for the swabs), the consumables can be packaged into sterilized pouches. A cheaper solution would be to use a plastic sealing machine.

In the following pictures of some of our printed consumables are shown.

Name	Image
pipette
spin column
swab
tube (1.5 ml)
tube (0.2 ml)

In the following, we analyze the cost of our printed consumables and compare these to market prices. The market prices where given by Bio.Kitchen. The complete calculation sheet can be found here. None of the calculation includes labor costs.

From this figure, it can be seen that our production prices are lower for swabs and 0.2 ml tubes, but higher for the other parts. However, we expect that ordering resin in larg amounts can further reduce the prices of our solution.

The next figure shows the amount of single consumables which can be produced with one of our tables in one day.

The red line indicated the amount of consumables needed for a single day. That means, our solution is not able to completely replace all kind of consumables without any lead time. However, we assume that shortages are known in advance and only last for a couple of days. If this is the case, our solution is able to bridge these shortages.

The next figure shows the money which can be saved per day and printer by producing consumables while there is no shortage. The most money can be saved if swabs are produced. However, since we can print more swabs than needed per day, merely printing swabs is not the way to go.

Due to the pandemic we had limited access to the laboratory at the university. Therefore we could not test if the production of the printed parts can be realized without RNA contamination. However, we were consulted by experts in that domain and ensured that producing RNA free plastic consumables in PCR laboratories is possible. Additionally we had to print our swabs with a different resin, since it was impossible to obtain the surgical guide resin from Formlabs, without exceeding the limit on our budget.

Nevertheless, we were able to print all required plastic consumables for a PCR test. Parts such as the 0.2 ml Tubes or Swabs can even compete with global market prices.

This is a non commercial project.

The material provided to you "as-is" and without warranty of any kind, express, implied or otherwise, including without limitation, any warranty of fitness for a particular purpose.