Following our previous progress report on November 7th we ordered more parts for our prototype, met with Dr. Michael Froehler twice, conducted our first formal Oral Presentation for Dr. Walker, and wrote two reports on our plans for the future marketing of our model.

Our initial order was approved by the BME department and included two 1.5 L water bottles, 3.5 mm inner diameter tubing, and a rubber gasket kit. We quickly realized that the first tubing ordered was too inflexible and would not transduce pressure well. We then ordered thinner, clear silicone tubing which is far more flexible than the original tubing. In creating our first prototype we have now realized this new tubing has too small of an inner diameter and so although it is incorporated into our current model, we will need to change it once we are at the stage of inserting a catheter into the tubing. Upon meeting with Dr. Froehler he recommended using thicker and wider tubing outside the nalgene (instead of our current model of using 1 type of tubing throughout) in order to reduce variations in our readings based on the pressure within the room as well as more accurately modeling the larger blood vessels which neurosurgeons thread the catheter through prior to reaching cranial blood vessels. We intend on ordering these new parts prior to the start of next semester.

Our first prototype is almost completed and is shown below. Additionally we show how portable this initial design is in the second image.

The prototype currently consists of the following:

• 1.5L Pink Nalgene
• 2mm x 3mm flexible silicone tubing (Gao Yang Tube M2541)
• X mm tubing leading to syringe
• Vaklok 60 mL locking syringe
• Plastic bladder
• Small plastic clamp simulating blood clot
• 2 EWG-1-⅛” x 9/32” grommets
• 1 EWG-4-5-8” grommet with a 9/32” sized hole drilled in it

The following additions were made to the 1.5L water bottle:

• 2 9/32” holes
• 1 ½” hole

These are the remaining steps in our prototype design:

• Adding T-connectors to the tube in 4 locations:

1. On the tube proximal to entering the water bottle
2. On the tube distal to entering the water bottle
3. On the tube proximal to the clamp inside the water bottle
4. On the tube distal to the clamp inside the water bottle

• Adding differential pressure gauges between T-connectors 1 and 2, and between T-connectors 3 and 4.
• Closing the tubing together to make one sealed circular system.

Since our last report, our team wrote a report on human factors that will need to be considered for our model’s market, as well as a report on what factors will need to be considered in marketing our model on a global scale. Overall we intend to keep the model as simple and cheap as possible in order to allow it to be introduced to more markets both within the U.S. and abroad.