Team:SDU-Denmark/Design
Design
Design of hardware
The designing and construction of the Prostate Malignancy Test (PMT) cup is problem-driven engineering. We have utilized agile design thinking by using iterative workshops, rapid pre-to-typing, and end-user communication. Furthermore, the use of strips as result indicators stem from reverse engineering of the well-known pregnancy test, which was used as inspiration for the concept.
As the Congenital Risk Assessment Test (CRAT) is very similar to the PMT in the testing process, the design would also be very similar in order to make the design process more efficient. The CRAT is, however, a little simpler than the PMT, which will be reflected in the design.
In the process of designing the hardware for PROSTATUS, it has been a necessity to maintain close communication with the lab team, as they have provided requirements for the function of the hardware. However, it has also had high importance to communicate with Human Practice, as they have gained knowledge about the end-user and the criteria they would possess for the comfortability and usability of the design. At last, we have also been concerned with the legal aspect regarding CE-markings, meaning that we have made sure to incorporate criteria that would make the design possible to release into the market (Directive 98/79/EC, 1998).
In the process of designing the hardware for PROSTATUS, it was crucial to maintain close communication with the laboratory team, as they provided requirements for the function of the hardware. Furthermore, the communication with our Human practices team provided us with the experiences and wishes of the end-users and with the new criteria for the design. At last, we considered the legal aspects regarding CE-markings to make the design ready for release into the market (Directive 98/79/EC, 1998).
Every step of the design process was directed by the Human practices and lab teams to refine the concept in the best possible way. The continuously changing criteria throughout the project resulted in several design iterations. Each iteration addressed new challenges and offered new perspectives on old ones, which eventually resulted in the PROSTATUS design. We facilitated a pre-to-typing workshop to include every part of our team in the initial idea generation and to get a common understanding of the different perspectives in the project.
In this workshop, several rough, yet good, design concepts were crafted and used for polished 3D CAD prototype drawings. 3D printed models were made from the drawings and they were evaluated against the original value proposition.
Engineering success of the prototypes
PMT Prototype
The prototype consists of 3 components: a cup, lid, and a sectioning part. The user urinates into the cup, where proteinase K immediately mixes with the urine. The proteinase K would already be in the bottom part – this ensures safety by avoiding any direct contact with the liquids.
The pills stored in the small compartments are then released into the urine solution when the user pushes out the middle compartment. A rubber ring in the rails prevents the liquids in the cup from mixing.
A concern discovered during the prototyping of the initial PMT prototype, was that the user urinates in a volume of approx. 300-500ml and would hereby require a high quantity of reactors, hence, increase the cost of the product.
To overcome this challenge, we incorporated a mechanical valve, that passes only a small amount of the urine into a separated sealed bottom part. After tightening the lid, the user pushes the button on top to activate the valve and release a small amount of urine into the bottom chambers – approx. two ml per chamber. The cup has a second wall with four small pipes guiding the pills directly into the bottom chambers. Finally, the testing strips are poked through the compartments into the liquids, allowing the user to see the results (See full manual here).
This design incorporates all the design criteria. The idea is based upon combining the test strips with the separation of liquids to perform multiple tests in parallel. The design aligns with the CE-directive criteria for eliminating leakage. Furthermore, one of the four compartments is used for user control to ensure that the test was carried out correctly. This both increases the credibility of the test to the user, yet accommodates the CE-directive.
CRAT Prototype
This prototype was designed for the CRAT and is in general very similar to the PMT prototypes. This prototype is, however, smaller as it only needs to contain a few milliliters of liquid. The prototype will potentially need more compartments than illustrated in the figures.
Test strip prototype
As the test strip is not allowed to be fully submerged, it was designed to only let the bottom of the test strip be in contact with the liquid. The pointy end of the strip makes it easier to poke through the compartments in the lid. The grips on the opposite end of the strip provide the user with a nice grip.
While the design of these prototypes was based on the physical requirements of the test, the final selection of the product hardware designs with implementations of feedback from our end users.
Reflective section
In general, the financial part of producing the hardware, has not been taken too much into consideration, as the focus has been to make a solution that accommodates the wishes of the end-users, and works well in accordance with what the lab team has discovered.
One thing that should be considered if this product was to be realized is therefore the whole manufacturing process of the cup. Even though the product is in fact rather simple, it doesn’t consist of any standard parts. Therefore, investments in machinery to produce the hardware would most likely be necessary, even though the production was to be outsourced.
