Week 4

7/6/2018

This week is the week of the Four the July. Most of the lab took off since Tuesday, and with my clinical mentor traveling, it has been a slow week in term of clinical experience. However, I am scheduled to shadow in clinic next Monday and Wednesday, and to observe in OR next Friday.

My loader project has been steadily progressing. The 3D printed parts came together well enough, and I calculated the angular velocity function respect to time needed to achieve uniformed linear motion. Unfortunately, with many attempts of controlling the rotational speed of the servo and traditional brushless rotational motor, we could not obtain a fine enough control of our angular velocity to get the (very slow) 1mm/s linear velocity. Thus, I have decided to forgo the crankshaft design and move to an actuator-like apparatus, of which the uniformed angular velocity of the motor will directly translate to a uniform linear velocity. Additional to the original criteria of the loader (controlled uniformed linear velocity of 1mm/s to 10mm/s, adjustable displacement control of 1mm-3mm, force monitoring, and alignment control), we realized that in order to apply force effectively on the knee toward the femur to rupture the ACL we need to stabilize at least one side of the knee --- tibial or femoral side. Because the tibia (lower leg) has less tissue around and thus is easier to fix than femur, we are building a stage with fixtures to clamp the lower leg and feet to secure the knee in a fixed position. I have finalized this iteration of design and the parts are printing as I am typing this paragraph.

One great accomplishment this week is that we managed to get everyone in the lab to be on board for this apparatus to be used on both mice and rats, instead of doing the manual closed ACL rupture with mice model. The biggest challenge and concern of using this apparatus on mice is their small size. A 1mm displacement of the knee is enough to rupture the ACL, and any distance larger than that can potentially damaged the PCL. However, with our new design, this concern will be addressed with four ways of displacment control. This redundancy should make sure that there will be no PCL damage. We are also implementing lasers for alignments, and with this new actuator-like design the speed control is made easier and more accurate. Once all these points were communicated across the table, the surgeons and the engineers are finally on the same side. This experience has taught me a very valuable lesson in communication, of how important it is to not only accept other people’s concerns and pay attention to their options, but also at the same time to be able to clearly articulate and stand by your own idea.

We visited the American Museums of Natural History and went to see our second Broadway show last weekend. Shout out to Raisa and Jacob for standing in line to get the rush ticket for us!

Fig. Titanosaurus of AMNH