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Design, protype, and manufacture test tube caps to allow for automation of COVID-19 PCR tests.

 

 

Team Members

Medha Prabhu    Saira Hussain    Ethan Trachtman    Emily Dennison    Madison Onesko    Nini Nguyen    Brian Bixler               

  

Project Poster

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Project Video

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Project Summary

Overview

This project focused on creating a new test tube cap to allow for automation of COVID-19 testing. The need for a new cap design originates from the Penn State’s Testing and Surveillance Center incorporating an automated testing method, using a TECAN liquid handling device. An automated system will decrease the risk of cross-contamination, increase the speed of testing, and require less manpower. However, currently the TASC has to run the TECAN machine without caps on the test tubes, while paperclipping the swab within the tube to the side, so as to prevent the swab from interfering with the machine’s pipette. Thus, our team was tasked with creating a cap that can be put on the COVID-19 test tubes and allow for the TECAN machine to run properly, while meeting the follow needs.

The new cap design needs to be self-sealing, leakproof, and capable of being penetrated by the pipette tip connected to TECAN’s automated liquid extraction device. The cap will also need to be able to withstand 1 to 10 freeze-thaw cycles with temperatures reaching around -80 degrees Celsius. The cap also should not affect the pipette tip’s electrical conductance, as this is how the pipette tip detects when it reaches the level of the liquid. The design of the cap needs to withstand a specific force so that the penetration of the pipette tip to the liquid will not cause damage. The swab utilized when performing the test must stay within the vial while the sample is being extracted. However, to ensure that the pipette tip will not pierce the swab and drag it across the sample platform, the cap should hold the swab to one side of the vial.

Objectives

– The Penn State COVID-19 Testing and Surveillance Center (TASC) tasked the team with developing an improved test tube cap that is compatible with the TECAN liquid handling device. This will allow for COVID-19 PCR testing to become automated, decreasing the risk of cross-contamination and expediting the testing process.

– The cap should allow for swab retention, have leak-proof capability, be able to withstand freeze cycles and impact tests, be made of a non-conductive material, and not cause overcrowding in the test tube rack.

Approach

– Needs and inputs for this design project were gathered through several online and in-person meetings with the sponsor, Penn State TASC, in which they outlined what problems they have with the current design of the COVID-19 test tube caps and what they would like to see in the new cap. Ultimately, our sponsor is our customer, thus, we were able to directly receive all of the specific needs for our design from them. During the online meeting, the sponsor was able to share visuals and specifications for the design that they desire. Furthermore, during an on-site visit to the TASC, the sponsor walked us through the PCR test process using the TECAN machine. This allowed us to see how the TECAN machine functions and learn exactly what our cap design needed to accomplish.

– Each group member created ten original concept sketches. The group then chose the best designs that fit all of the design requirements and customer needs.

– A patent search was then conducted first through the USPTO’s Classification Text Search Tool to find relevant CPC. Keywords used in the search include: “vial caps”, “test tube cap”, “leakproof”, and “contamination”. For the keywords “test tube cap” and “contamination,” the results were not relevant to the patent search. “Test tube cap” did not return any results with “test tube” in the patent search. “Contamination” returned results related to testing methods, rather than containers in which the testing samples are held. Ultimately, the group found that there were no existing patents with a test tube cap design similar to ours.

– SolidWorks and CAD models were created of over 10 different design variations, each of which were 3D printed. About 15 different designs were modeled and 3D printed before the team produced a successful prototype that appeared to meet all needs.

– To test the functionality of the test tube cap prototype, we subjected it to several freeze-thaw cycles (-80 degrees celcius). Additionally, the cap was turned upside down and shaken to test its leak-proof capability. Lastly, the cap was thrown on the ground and dropped severeal times to test its durability and resistance to being dropped.

Outcomes

– We created a cap that is self-sealing to prevent leaking of the fluid inside the the test tube, interlocks with the other caps to allow them to stay in line without overcrowding the rack, allows for swab retention so as not to let the swab interfere with the machine, and prevents cross-contamination.

-Freeze-thaw cycles and impact tests were conducted to imitate storage and transport environments. From these tests, there were no negative effects observed on the structure and function of the cap.

-The design was also determined to reduce cost, as our design acts as a universeral test tube cap, since it is snap-on and accommodates any test tube, even those with threads.