Week 3

6/29/2018

This week has been a slow one. I submitted a revision for my IACUC protocol to address some logistic questions the reviewers asked. With the speed of things has been moving, I am starting to worry if the protocol can be approved by the end of July. Nevertheless, the practices on cadavers continued from last week and I got the chance to practice suturing techniques.

I spent majority of my time this week going through the iterations of my PTOA loader design. The goal of this loader is to have a motorized uniformed linear motion with control force and displacement, and optimally with a way of aligning the direction of the force with the femur. The alternative opinion in the lab is to induce the ACL rupture manually with a load cell monitoring the force exerted and discard the animals of which the measured force is high than a certain threshold. The alternative method, though it requires more skilled animal users, is much easier to develop than the motorized loader. Thus, the time on the loader design and prototype is very tight, as well as the budget. My initial design can successfully achieve motorized linear motion with displacement control and force monitoring. However, because of the simple crankshaft design, the uniform linear motion cannot be accomplished. As a matter of fact, as long as the slider is doing a piston motion (that is, all the variation of the crankshaft design) it is bound to accelerate and decelerate thus not able to move in a uniformed linear motion. Unfortunately, our budget does not allow us to get a linear actuator unless there is absolutely no other way. To solve this problem, I am trying a method of varying angular velocity of motor rotation, as a function of crankshaft arm angle and time, to obtain a uniform linear velocity. Luckily the displacement needed to induced ACL rupture is very small and can be achieved within the first quarter of the crankshaft arm rotation, making this method of controlling linear velocity possible. These are all still on paper, I finished printing all my parts today and the testing should begin next Monday.

Due to Dr. Rodeo’s schedule and other scheduling issues, I have still yet to be able to observe in clinic or OR. I am actively trying to resolve this.

(figure: 3D printed parts under UV light)