At Francis Medical, the cannula of our disposable delivery device is inserted into the urethra and then a small round catheter exits the cannula into the prostate where steam exiting from the catheter is used to ablate tissue. Due to hydrostatic pressure from the bladder, the dynamic seal between the cannula and catheter is the only barrier for a possible fluid ingress pathway into the delivery device, which is undesirable. 

Testing the dynamic seal on the bench is accomplished by pressurizing the cannula using a pneumatic pressure decay tester. While the output of this tester is continuous, the distribution is bimodal and is best modeled as a binary output: either the seal leaks or the seal does not leak. In JMP, there is no straightforward method to calculate the power and sample size to allow for comparison of different design of experiment (DOE) studies for an attribute output.

In this paper, we outline the process methodology we used to determine the number of factors to test and how many runs to complete, including a simulated power analysis. In addition, we discovered a unique way to condition the samples prior to pressure decay testing to create more dynamic seal failures than achieved through historical testing. In the end, the results of the experiment allowed us to make definitive design decisions with confidence and improve the dynamic seal performance by a factor of 25 from the current design.