The lab automation team received an update this week that we basically had to re-vamp a large portion of the project, since the gantry was(apparently) no longer deemed necessary. Our goals were reset so that everyone on the team was set to work on the "NEW" lab automation plan, which was to combine the liquidation handling, the spin coater, and the thermal heating system.

For starters, me and the rest of the team took a look at an iteration of the three in one spin coater that was already on the internet(and made at an extremely cheap price) as well.

Of course, since this was an extremely low budget design, we realized that there were several improvements we could make. For starters, the liquid handling system is basically composed of a single syringe, as well as a better solvent catch bowl system to collect excess liquids. Along with that, a more efficient vacuum system would benefit the spin coater, since the current iteration does not suction the silicon hard enough to keep it in place consistently at higher rpm.

When it comes to major roadblocks, several new variables came into mind once we decided to merge all the components of lab automation into one. The biggest one for sure as of now, is the fact that we may have to pursue a different filament or material for the base of the spin coater due to there being a solid chance of it not being able to withstand the heat. The original spin coater was also not stationary enough(due to how light it was), so utilizing aluminum as the base instead was a suggestion that came to mind. Other roadblocks include, as mentioned, improving the vacuum system of the spin coater, minimizing motors(since the less moving parts, the easier time we will have), and attaching an updated liquid handling system that can alternate between different chemicals(since we have to differentiate which liquids are which within the tube)

For next week, I plan on initially CADing the base design of the spin coater(while taking into account the liquid handling + thermal heating) , and attempting to help Adwoa move her Fusion360 file of the perstaltic pump to onshape(while maintaining her sketches).

Before receiving updates on what I was supposed to work on this week, I helped Anirud re-CAD and 3d print several modified components of the Spin coater. The dimensions of the spin coater were increased in length by 45 mm, and the holes for buttons were more enclosed together due to wire entanglement concerns, and the buttons not being fully optimized for assembly. Along with that, the holes for motor attachment were slightly modified so that all four screw holes would accurately fit in the motor. The height of the vase was also slightly decreased to account for the addition of a top plate on the spin coater. All of these revisions ended up significantly increasing the efficiency of the spin coater's ability to hold silicon in place. The only major roadblock along the process was failing to recognize that the BAMBU 3d printer had different setting from the default BAMBU settings, as well as the PRUSA filament toppling over, resulting in some prints being scrapped.

I additionally began to conduct research on the pinch valve mechanism that I discussed with my fellow lab automation teammates, and began investigating the pros and cons of utilizing such a design in contrast to the original peristaltic pump. The pros include the fact that the basic mechanism for the pinch valve is a lot less complex, since it involves one or two motor simply twisting a screw to completely enclose water flow. The major downside is that a large majority of pinch valves attempt to "pinch" by enclosing both sides of the tube instead of only one. The largest road block as of now, is figuring out if there is an efficient pinch valve design capable of "pinching" the tube on both directions with one motor, while also being compact enough to fit with the rest of the lab automation components. Furthermore, the pinch valve is not suited for high temperature purposes, and I am not completely sure what temperatures the liquids will be operating in.

For next week, I plan on CADing two or three different iterations of the pinch valve, depending on if I determine that pinching the tube on both ends is possible with one motor. If possible, I will attempt to use FEA to determine if the liquid flow through the valve is minimized and compare the designs and check which one offers the least liquid flow.

https://tameson.com/pages/pinch-valve(resources used for general understanding)

After several failed attempts to move Adwoa's Fusion 360 files to ONCAD, I decided to manually attempt to recreate a new peristatic pump inspired by her old design, as well as taking into account the new gearbox motor setup we were utilizing. The main roadblock involving moving the Fusino 360 files was the fact that there was no way to preserve sketches used in the CAD, making it much harder to get a general idea of dimensions and what tools were used to make these components. Furthermore, all of the CAD in Fusino 360 was made in 1 file, making sketches impossible to fully keep track of(since we needed to find a way to seperate them into seperate components, but that would not preserve sketches made in 1 file).

To compensate, I decided to devise a new peristatic pump design utilizing Adwoa's old design, but modifying it to match the new motor setup being used(being a 27:1 gear box attached to the same stepper motor). Although the motor not having enough torque may have been the reason why the pump did not work as intended, I was also willing to bet that the PLA structure was not strong enough either, so I decided to make a more rigid structure, as well as utilizing more infill while printing. Although, a major downside is that the new structure may not be as space efficient as the old one, but considering that it will no longer be part of the gantry, that is not an issue at all. The largest roadblock while CADing, was definitely getting used to ONSHAPE features, since I could not recognize the tools I used to know in Fusion 360. However, the main design of the pump is being preserved, and I plan on utilizing a compact structure, at the cost of utilizing more bolts on the design.

By next week, I plan on begin prototyping the pump, as well as beginning to help Advaith with full assembly of the multipurpose spin coater(since we currently are not 100% sure on whether to move the spin coater itself, or the liquid handling and heating system).

What was accomplished:

1. Finished designing the peristatic pump, and got the 27:1 gear motor attached to the mechanism

2. Researched syringe pump method as an alternative option in case the peristatic pump wouldn't work. Designed several diagrams, but before reaching CAD phase, found a lot of critical drawbacks that convinced me to use the peristatic pump instead(including linear actuators that require built in encoders)

3. Start working on PPT for the presentation on tuesday

Roadblocks:

1. 3d printed parts for the pump(may be accurate, but should have initially been designed to account for clearance holes for drilling through)

2. Finding the right material for syringe pump(a glass syringe would be optimal to handle all the liquids required, but the larger models do not have built in syringe needles, so a glass syringe + recyclable needle with luer locks was thought out)

TO DOs:

1. Finalize PPT for tuesday

2. Help Advaith move the pump mechanisms into the overall assembly, as well as implementing other components(Im not sure how the spin coater is going to look like)

1st week: reviewed the hackerfab syllabus and got registered on gitbook