Iterative DBTL Cycles

This step in our design process begins our 3D modelling and printing stage. Prototypes were welcomed, such as custom clay molds to better understand our user’s comfort and quantify thicknesses. Many DBTL cycles were required to reach a viable product.

DBTL #4

Primarily, we were hoping to first check our design process with Dr. Kudzia thus far and see what the next steps for us should be as well as check what kind of material he suggests for us to use given the profile of our user. We shared our concerns with him about our current software not being fully available for our use and he suggested that we enter the SBME makerspace at UBC and physically interact with the materials available. His main lesson to us was that we need to get into the studio and make multiple designs with cheap materials so our ideas can be tested. Upon us saying we had made multiple C-sketches, he shared that one can only make so many designs and it would not be sufficient until we get in there and make things. He suggested multiple softwares with each having different purposes: Ansys for stimulations and stress analysis, autoCAD for stress analysis and robust 3D designs, and meshlab as an accessible software with which we can scan 3D objects and trace them into the CAD world to print.

Considering that the majority of our team are not experts in 3D design, we wanted to confirm that what we have been doing thus far is valid. It was great receiving confirmation that it was, but also getting motivated to make 3D designs and physically interact with our ideas. We learned that making multiple prints with cheap materials and making robust examinations of how well they meet our user’s needs should be our next step.

At this point, we started to self-train on creating CAD designs and took advantage of our dry lab members’ resources in3D design by undergoing dry lab training. Starting with Onshape—a classic, yet intuitive design software—we gained a foundational understanding of 3D design. Our next steps were to make those designs and meet with our user to solidify our associated requirements, enabling us to both quantitatively assess how well each design addressed her needs and come up with a finalized design to iterate through.

CAD #1

Thus, based on discussions, we began to make CAD designs of our C-sketches from Round 2. We made baseline CAD designs to better understand which measurements needed to be taken to make the designs catered towards our user and; the measurements are arbitrary but the curvature and level of thickness are aspects of the design we had to determine.

We made multiple attempts to determine how we could CAD a specific curvature, which our stakeholder would tell us what is most comfortable. The first version was designed to cover the entire pipette and to add palm support. The second design prioritized having as light of a design as possible, therefore removing the palm support. Both excluded the wrist extension so that the initial shape could first be focused on. It is also important to note that both of these prints are impossible since they create a point of infinite thinness, so we knew we had a lot more to do to build these designs.

Design E Version 1 Design E Version 2

Based on our co-PI’s advice, we brought air-dry clay and a broken pipette to create a rough prototype and make the aforementioned measurements as well as cardboard to mimic the wrist extension.

Before the interview began, we ensured that our user understood she can end her participation at any point, ensuring we are continuously getting consent. We had our user physically interact with different shapes and sizes of clay, to learn her preference. She stated she preferred when there was an increasing thickness to the tips of her fingers rather than a uniform thickness around the pipette. She also said it is more strenuous if there is no support for her palm, making the second version of Design E unsuitable.

However, there were also surprising elements to our conversation which contradicted what we had previously discussed. Given that our user had just met us after a long day of work, she was able to point to areas of strain and difficulties that our previous conversations had not covered. When going through our satisfaction curves, she highlighted that the one catered towards repetition is inaccurate as she was actively experiencing strain in both her shoulder and wrist. As a result, our previous notion that the wrist support in Design E would guide the user towards using one muscle at a time might not be as clear-cut of a solution to repetition as assumed so we had to take it out of the requirements. She also emphasized that bending her wrist is her preferred state, and wouldn’t want something preventing her from bending her wrist. We therefore removed the wrist support as a design requirement all together.

From this, we learned that testing our physical prints would enable us to test whether our designs are actually helpful, and that we must be prepared to make adjustments along the way. When working with the pipette, she also highlighted that the height of the pipette knob causes strain in her thumb, whereas the lack of physical interaction with these tools in our previous meetings had resulted in her assuming that the knob does not add to her strain (Interview #2). From this, we decided to model a knob add on, which we would further explore if time permits due to it being a separate design. Additionally, she stated that a softer, compressible material would help a lot, making it a user requirement.

We modified our requirements and evaluation criteria and satisfaction curves to include these new insights. Finally, we gave her clay and asking her to mold it into what she felt was the most comfortable for her. This allowed us to see what the optimal measurements were for our add on.

Because of this change in opinion, the previously failed designs D and H have now passed. However we decided not to pursue H, due to it not being similar to the shape that the user stated was optimal.

We populated the following tables as we made different thicknesses around the pipette using clay and came up with optimal measurements to use in our CAD, the thickness corresponding to a satisfaction of 10/10. We later used a caliper to take exact measurements of both the Rainin Pipet Lite (our user’s favourite pipette that we designed the add on for) and the clay mold she made which received a rating of 10/10. We were able to subtract the thickness of the pipette from the clay prototype to design our CADs.

Measurements of Different Thicknesses of Clay

These were measured during our user interview. We added increasing amounts of clay to the pipette and got her comfort rating at each point. After stating her comfort, we measured the thickness using a caliper. We then removed clay once it had passed the point of comfort.

Table 11. Comfort Charts: Thickness of Clay vs Comfort

Mold iteration	Thin (mm)	Mid (mm)	Thick (mm)	Comfort rating (out of 10)
1	7.24	11.0	10.55	8
2	6.35	19.0	14.34	8
3	10.78	(misssed)	37.0	2
4	10	26	13	4.5
5	without clay	without clay	without clay	5
6	7.54	23.05	14.15	6
7	5.65	13.38	19.68	8.2
8	10.47	10.47	11.11	10

Thin = Thinnest Part of the tool, which is at the palm area

Mid = Middle part of the tool, which around the base of the fingers

Thick = Thickest Part of the tool, which is at the fingertips

Measurements of Clay Prototype versus Pipette

Measurements of the Pipette

Decision Framework #3

Based on all that we learnt, which includes conversations with our user and with our co-PI, we finally understood what the WDM should be, creating our final WDM, evaluation criteria and satisfaction curve. However it’s important to note that although the weight of the pipette was a key requirement for the user, if we are adding a tool to the pipette, it is difficult to lower the weight of the pipette itself. Therefore, our main target for the design is lower the gripping intensity, while ensuring the weight of the tool is as light as possible.

Table 12: Combined Weighted Decision Matrix - Finalized

Order of importance	User Statement	User Need	Associated Requirements	Quantified Associated Requirements (Evaluation Criteria)	Weight
1	”Strong gripping intensifies my hand/wrist pain.”	Reducing the need for extensive gripping	Increasing the surface area of pipette body, to reduce amount of grip tension needed.	Decreased grip strength needed compared to regular pipette.	60%
2	”Weight of pipette influences pain.”	Ensure the pipette remains light	Pipette add on must remain light	Combination of pipette and add on must remain as close to the lightest multichannel pipette as possible	28%
3	”Mechanical stress on the palm”	Reduce pressure on the palm and associated areas.	Use soft material	Material must be more compressible then the pipette plastic	8%
4	”Forceful pushing of pipette knob stimulate pain in my hand/wrist/forearm”	Reducing the pressure needed to handle the pipette knob	Reducing the pressure required to turn the pipette knob or press down	Decreased force used when pressing pipette knob compared to regular pipette through providing a platform to place the thumb.	4%

Table 13: Evaluation Criteria - Finalized

	Evaluation Criteria	User Descriptions	Satisfaction Curve - Justification
1	Combination of pipette and add on must remain lighter then the lightest multichannel pipette.	Closest to as light as possible is preferred with a balance of light and heavy to have sufficient grip. 100% would be a bit lighter than current use (multichannel pipet-lite which is 240 grams), 0 would be heavier then the one she can’t use (regular rainin which is approximately 450 kg). Regular rainin would be 50%, same weight as light pipette you are using is 90%, if it was half way between heavy and light it be 70%.	The user described the weight and her satisfaction having a direct relationship. The tool weighing 0 grams gives 100% satisfaction but is unrealistic, so a point discontinuity describes that the lightest tool possible is most ideal.
2	Decreased grip strength needed compared to regular pipette.	intensity of grip after 45 min of gripping heavy pipette would be 0%. Equivalent is 45 min of straight dilutions. 100% would be the first moment of using lightest pipette. 50% intensity of grip after 22.5 min heaviest pipette.	Our user described grip strength reduction to be directly proportional to her satisfaction. See user descriptions for other properties of the curve.

Satisfaction Curve #2

DBTL #5

Mark 1

Moving laterally from the corner of the pipette add on, lines starting from the outer shell of the add on (where the hand goes) that are also normal to the rim aligned with the opening were drawing. Distances of 2.909 cm, 4.269 cm and 4.053 cm as well as 3.683 cm were calculated as the optimal total thickness of the outer shell by subtracting the corresponding pipette widths (measured using a caliper) from the clay mold made by our user. This gave us the net thickness added to the pipette that would make our user most comfortable. The actual width of the opening and longitudinal distances of the add on were calculated by directly using the measurements from the pipette, obtained from caliper measurements that are sketched out and shown above.

We decided we would want to first print in PLA to save money, then once we determine our final CAD design we could print in a polyurethane.

Test #1

DBTL #6

Mark 2

Test #2

DBTL #7

Mark 3

Test #3

DBTL #8

Mark 4

Test #4

DBTL #9

Mark 5

Test #5

Additional CAD designs

We hoped to have created different functional prints of the other designs that were examined during C-sketch round 2. We wanted to be able to compare the different designs to determine which worked best for our user, and grade them against our WDM. However due to time constraints, we were unsuccessful in fully pursuing these alternative designs. Below, we have documented other CADs we hoped to have further explored, however were not able to because of the time constraint. We share these design in the hopes that other teams can build off of where we left off, further improving inclusivity in wet labs.

Design D, Round 2

Design D featured an ergonomic extrusion where the palm of the hand would enclose. Ideally, this would be modelled exactly to the curvature and fit of our user’s hand. This current CAD model is only a prototype of how the tool would look, and was not modelled to the exact measurements of our user’s hand. The tool is split into two pieces and would have been attached after 3D printing with straps. Straps were hypothesized to be velcro (but wouldn’t have met the sterilizability requirement) or 3D printed as well with a flexible material.

After 3D printing, the largest areas of DBTL was the size and improving the accuracy of the channel meant to fit the pipette body. The print came out significantly smaller than intended, but scaling the entire tool up would fix this. For the pipette body opening, one solution is to apply the radius curvature measurements derived from a previous design to get a more accurate pipette body cavity. Ultimately, as we ended up pursuing Design E we did not exhaust further DBTL cycles towards this design, but we acknowledge the steps we could have taken to improve this design.

Knob Extension

Although this CAD was designed, once we tried to print it, the overhangs caused the 3D print to fail. Due to time constraints, we were unable to reprint and test it.