Preliminary Detailed Design
Table of Contents
Team Vision for Preliminary Detailed Design Phase
- Determine how to integrate Adruino into bioreactor
concept design with consideration of well plate location
and wiring set up.
- This is important since we do not want outside variables to damage the controller.
- Conduct tests with media and various electrodes
readily available in the lab: brief observations of
physical and chemical changes will be monitored to
determine more advanced testing parameters since initial
reactions are unknown.
- This is a crucial component of the analysis to make sure the electrical circuit design will meet the needs of the bioreactor.
- Solutions for mechanically securing the container
into the system body will be drafted, modeled, and tested
- This will allow a better understanding of how much material and what type will be used to generate the Bill of Materials.
- Determined what cell line we are using, SHOCKS2. Currently there was minimal planning and testing on the Bio-Medical side since a majority of Preliminary Design Phase was focused on the Mechanical components before testing can be conducted.
- Continue to assess potential risks with electrode material and configuration.
- Demonstrate that our testing methodologies will satisfy all of the Engineering Requirements stated on the Problem Definition Page.
Prototyping, Engineering Analysis, Simulation
Overview: Arduino housing top has curved edges (fillets) that will aid in avoiding interference in sealing the housing. Rails base are used for constraining the 6 well plate in the vertical direction and both have fillets for ease of placement. The base is the bottom for all walls. The back plate lies behind the side walls. Support bracket behind housing top for added strength in the connection between the hinge and the top using nuts as fasteners. Strategic placement of tapped holes and counterbores for no break-throughs. Arduino is sealed from incubator conditions to avoid electrical damage. Back plate and base plate are made of Delrin plastic for frictional and insulation purposes. Delrin is wear resistant, machinable, impact resistant, and moisture resistant.
Future Design Considerations: Clearance for hinge support bracket and nuts. Threaded inserts instead of any tapped holes in plastic. Addition of electrical contact connections and clearance holes for wires. Appropriate tolerance for door fit and function. Addition of handles on sides and on door.
For Pugh Chart Comparisons Currently on Edge: The concept detailed above houses the Arduino above the 6 well plate. The plate is constrained by the base of the bioreactor that it is inserted onto for use. The concept detailed below shows the 6 well plate above the Arduino housing. The plate is held in an elevated position by support brackets.
|P18082 Concept Generations Focal Points|
|Arduino Housing Location||Above Well Plate||Above Well Plate||Below Well Plate||Below Well Plate|
|Arduino Housing Access||Door on Hinge||Door on Hinge||Sliding Door||Sliding Door|
|Spring Mechanism||Leaf Spring||Spring Detent||Spring Detent||Leaf Spring|
|Well Plate Location||Bottom of Bioreactor||Bottom of Bioreactor||Top of Bioreactor||Top of Bioreactor|
|Preliminary Detailed Design Pugh Analysis 1|
|Well Plate Accessibility||Datum||0||-1||-1|
|Ergonomics of Handles||-1||-1||0|
|Weight of Unit||-1||0||-1|
|Cell Culture Viewability||-1||0||-1|
Selection Criteria Description
- Well Plate Accessibility: Refers to the ease with which an individual may access the cell culture within the bioreactor.
- Adruino Accessibility: Refers to the ease with which an individual may access the cell culture within the bioreactor.
- Ergonomics of Handles: Refers to the each with which an individual interacts with the bioreactor in terms of portability in and out of the incubator and moving across room location.
- Manufacturing Complexity: Refers to the time, and effort, that would be required to build the prototype and integrated control systems.
- Weight of Unit: Refers to the weight disruption load of the bioreactor and effort for an individual to lift and place bioreactor onto incubator shelving units.
- Sterilization Time: Refers to the time required for sterilizing of the bioreactor including the bioreactor itself and well plate culture assembly.
- Portability: Refers to its likeliness to create issues due to size and space consumption as well as the overall hardiness of the system (i.e. whether the device will be able to survive handling by multiple individuals over the course of, at least, 3 years).
- Cell Culture Viewability: Refers of the cell culture to be viewed without a microscope to make sure electrode, media, and wiring configurations have good status between cell culture media removal/replacement as well as microscope viewing.
|LabVIEW Controller Design Concepts||Pros||Cons|
Feasibility: Prototyping, Analysis, Simulation
|Electrode Material Observations|
- The copper showed clear signs of corrosion as the submerged surface of the positive electrode turned the tell-tale green during the test. This is most likely due to the acidic nature of the media.
- Stainless Steel:
- The stainless steel showed significant pitting on the surface of the positive electrode that had been submerged. Sandmeyer Steel Company claims on their website that “Pitting occurs mainly in the presence of neutral or acidic solutions containing chlorides or other halides.” Though there don’t appear to be chlorides or halides in the media, the acidity of the media is the likely cause of the pitting, similar to what happened with the copper.
- While the carbon electrodes don’t appear at to have sustained damage, it is difficult to prove that they didn’t react with the media, as the media still changed colors, and experienced significant bubbling.
- Thoughts for Moving Forward:
- Test again comparing Carbon with Chromium, as Chromium is incredibly resistant to corrosion, even in acidic environments. Use pH testing, and keep track of media loss due to foam production by measuring the amount of liquid media before and after.
Drawings, Schematics, Flow Charts, Simulations
The images below are 3D modeling of the preliminary design concept 1 for the electrical bioreactor. The link provided redirects to the drawing schematics accompanying the design concept shown below.
Link to live P18082 Bioreactor Design 1 Schematics
Bill of Material (BOM)
Link to live P18082 Bill of Materials
|Preliminary Test||Preliminary Test Outline|
|1. Temperature and Humidity Test||
|2. pH Test||
|3. Electrode Durability Test||
|4. Microcontroller Durability Test||
|5. Voltage Test||
|6. Accessibility Test||
|7. Assembly Test||
|8. Cleaning Test||
|9. System Durability Test (this may require durability tests of multiple components)||
|10. Ease of Use Test (Control System)||
|11. Handling/Size Test||
|12. Sterilization Test||
|13. Safety Test||
The Risk Assessment is carried over from previous Design Reviews with the added risks of electrode complications.
Currently electrodes are chemically reacting with the media which includes and is not limited to the following: pitting, corrosion, acid-base reaction, decomposition reaction.
Link to live P180821 Risk Assessment Preliminary Design
Plans for next phase
As we move towards the end of MSD I, we must solidify our design specifications, and make manufacturability plans that will allow us to build the first full prototype in February 2018, so that the iterative process of testing and design changes can begin in early March.
- - The six-well plate securing mechanism needs to be drawn up for production
- - The drawings should be finalized and ready to be used in January
- - More testing needs to be conducted to determine which electrode material to use
- - Circuit Diagrams/Schematics should be finalized
- - A Digital-to-Analog-Converter (DAC) should be compared against Pulse-Width-Modulation to determine which is better for inducing a cyclic voltage on the media
- - Assist with the electrode testing by measuring the effects of the electrodes and voltages on the media (i.e. pH, color, mass retention, etc.)
- - Make final preparations to ensure that all necessary testing materials and equipment will be ready MSD II
- - Create clear vision and schedule for December through the end of February
- - Ensure all necessary tasks are met
- - Prioritise risks, making sure to tactical the highest risks first
- - Make any necessary final changes to the Bill of Materials
- - Go back through the risk assessement to check of things that have been adressed, and make sure new risks have been added