January 22 - January 29

This week, the Power Puff Girls worked to come up with a better design for the collection device. One aspect of the collection device that kept causing problems was the base. Having a lose base created canals and pathways that the fluid would travel through, and was not the same during each test. The new idea was to attach a bag to a thin acrylic piece shown in Figure 1. This would keep the base flat and contains a small hole in the corner for the fluid to leave the system. A more descriptive design will be shown once the apparatus is put together.

Figure 1: The base portion of the collection apparatus to be placed on the magnets.

Also, the girls worked to make the re-circulation device smaller. During testing, calculations were made, and we found that the rate the fluid was flowing during the previous testing was too quick. In order to reduce this, we reduced the volume of the re-circulation device and the tubing.  This should allow for the fluid to flow through at a rate of 2 ml/s. The device was simply scaled down and no major changes to the structure were made. The new device is shown in Figure 2.

Figure 2: A scaled down version of the re-circulation device chosen during previous testing.

Lastly, calculations were made to find that the maximum shear stress the blood can handle without damaging the cells is 150 N/m^2. This value will be used as a base for any alterations that need to be made on the re-circulation device in the future