Table of Contents
Team Vision for System-Level Design PhaseDuring this phase, our team planned on further continuing to define the project direction with our customer through multiple system level design analysis tools to determine optimal system designs. Though our project's scope and overall deliverables were modified at the beginning of this phase following our first design review, we were still able apply all of these system level design tools to determine optimal designs all while retroactively updating all previous material to meet these new customer specifications.
Customer MeetingLive Document: Customer Meeting Minutes Following Week 3 Design Review
Following our team's Week 3 Design Review, our customer asked to meet with us to reevaluate the initial scope of the project and refine deliverables. It was decided that the project was better suited to focus on process improvement of the current process in place by implementing the image analysis software. This change in deliverables from a physical cell factory to process improvement was prompted due to the feasibility of being able to design a product that was manufacturable to necessary standards for cell culturing on the available budget.
Live Document:Functional Decomposition of Cell Culturing Process
The main goal for the functional decomposition is to take the overarching task of cell culturing 3T3 fibroblasts and break it down through smaller components working down the chart. As you work down through the chart, each new row of boxes is answering the question of 'how' to the connected box(es) above. In contrary, when working your way back up the chart, the connected box(es) in the row above are answering the question of 'why' that box is in place.
Live Document: Benchmarking Image Analysis Software
Since this project is focused on process improvement rather than the development of a physical product, benchmarking was performed on the potential image analysis software that our team plans on using in the cell culturing process.
Live Document:Concept Development for Cell Culturing Process
To develop potential system level designs for our process/project, each of the headings from the functional decomposition chart were analyzed to ensure that all crucial components of the design were addressed. For each of these functions, between four and five options were listed as potential actions/designs. These options ranged from very unrealistic options to the current baseline to stretch goals of automation.
System Level Design Concepts
Live Document: System Level Designs
Using the concept design options identified for each of the crucial process functions, four different system level designs were identified. One design is the bare bones (current) design, there are two realistic options that use different imaging analysis techniques, and a fourth design that is a stretch or unrealistic option that includes automation in liquid handling steps.
To effectively evaluate each of these system level design concepts, a series of criteria were developed to review each of the designs with in comparison to the other designs. These criteria are:
- Is sterility maintained?
- Are conditions maintained?
- Reduces time?
- Simple user interaction?
- Consistency in results increased?
- Reduces user error?
- Is the process cost efficient?
- Impact to budget?
- Ability to build in one semester?
- Have all skills required to complete (EE)?
- Set up time?
- Maintenance required to maintain process?
- Requires new software or coding to be developed?
- Energy required to run?
Each of the four designs were to be evaluated against these criteria. First the bare bones design was set as the datum or control that other designs were evaluated against. This constructed a score or ranking of '+' (positive change) and '-' (negative change) for the other other three designs. After this evaluation the datum was changed first to the realistic option 1 and then the realistic option 2.
Live Document: Concept Selection Pugh Charts
When reviewing the three separate Pugh charts it can be seen that the realistic options 1 and 2 both showed an increase in the number '+' and a decrease in the number of '-' when the datum was changed between the bare bones and and realistic options. This supports that these process improvement steps will lead to an improved system design and overall refined process based on the selection criteria.
Feasibility: Prototyping, Analysis, SimulationThe system level design options that our team plans to implement in our project have been narrowed to the two realistic options above. These options are both very similar in overall process and simply differ in what imaging analysis software tool is used. By using the benchmarking information collected along with running tests of counting cell numbers and observing cell morphology, the optimal imaging software tool will be determined. This determination will be highly based on the accuracy and consistency in measurement as well as the ease of user interface with the process.
Testing PlanningLive Document: Testing Planning for Next Phase
Based off the system level design and the key areas of focus, rationale for testing was constructed. This rationale walks through the different variables at in the process and which of those are controllable and non-controllable. The controllable variables were then ranked for level of influence on the growth curve for cell culturing. These higher ranked factors will be the key factors that are focused on during the testing phase of the project. These keys factors are related to cell seeding density and quantity of media, or simply the ratio between media and cells.
Automated liquid dispensing can be achieved by using pressurized lab air that is available in most standard cell culture labs underneath the hood, which is a sterile working environment. A container which is filled with the working fluid is pressurized and maintained at a low stable pressure by a passive compressed air pressure regulator. The pressurized head-space above the working fluid forces the fluid to move out of the container through the aseptic fluid transfer cap. An electrically actuated on/off valve will control the flow of fluid from the container to the dispensing tip. The volume of the fluid dispensed can be precisely controlled by the timing of the flow control valve. Please note that the resting state of the flow control valve is off, protecting against fluid dispensing if the device is disconnected from power or the operating software malfunctions.
By distributing the pressurized air to multiple containers through a manifold, this concept can be implemented to deal with multiple different fluids at once. Since sub-culturing cells requires the use of many different liquids being dispensed in precise volumes a system such as this could reduce the time and difficulty of the sub-culturing process.
Automated liquid removal has some obstacles that need to be addressed that are not present in automated liquid dispensing. An automated liquid removal system must have z-control to allow a pipet tip to descend into the petri dish containing the working fluid. Additionally, a new pipet tip must be supplied to the removal system for each individual liquid that is being processed in order to prevent cross-contamination between liquids.
The sub-system concept design shown demonstrates a syringe barrel connected to lab vacuum, which is controlled by a pneumatic electrically actuated on/off valve. When removing a liquid from the petri dish, lab vaccum will be supplied to the descending syringe barrel which will interact with the pipet tip that is in the pipet magazine. When finished, the syringe barrel will ascend and detach from the pipet tip (which will remain in the pipet magazine). When a new fluid is to be removed from the petri dish, the pipet magazine will index to the right to supply a new pipet tip for fluid removal and the process will repeat. Z-control of the syringe barrel will be accomplished using a dual worm drive stepper motor configuration, while left-to-right indexing of the pipet magazine will be accomplished by using a single stepper motor equipped with a belt drive.
Live Document: Risk Management
Since the Last design review, multiple items have been either revised or added to the risk management document. These items are more closely focused with the systems level design that has been determined through this phase. These risk management items are now focusing more closely on specific operator actions through out the cell culturing process.
Plans for next phase
Tony Yosick's Three Week Plan Live Document: Tony's Goals
Philip Tinder's Three Week Plan Live Document: Philip's Goals
Christa Vuglar's Three Week Plan Live Document: Christa' Goals
Charles Henle's Three Week Plan Live Document: Charles' Goals
Emma Kate Flanagan's Three Week Plan Live Document: Emma Kate's Goals