FPrin Case Study 1 – Design Capability

Wearable Pump Capability Study


  • Client was unsure of robustness and fundamental viability of novel wearable pump concept
    • Some initial prototyping and testing yielded mixed results
  • The anticipated multiple cycles of prototype / test / iterate needed to establish viability would be expensive and many relevant test configurations – e.g., extremes of tubing dimensions – were inaccessible

KDPD Approach:

  • Created an analytical model for existing pump architecture
    • Verified and supplemented analytical model with low level testing on device subsystems and components
    • Performed Monte Carlo simulations and capability studies on several key metrics of the pump to assess capability at scale
  • To evaluate the robustness of the design we used the capability index Cpk (commonly applied in component manufacturing) at the system level
We considered the 4-sigma, 99.35% yield, case where Cpk must be greater than 1.33.


Metric Cpk Meets with Margin Does not meet
Pumping Force
Delivery Accuracy
Delivery Rate
Battery Life
  • The results showed that this pumping architecture had fundamental shortcomings in several key metrics and is very likely not viable

Key Takeaways

  • Analytical model and low-level testing approach allowed FPrin to identify that the design in question was not viable
    • Identified technology as dead end quickly and at modest cost
    • Saved client prototyping and testing time and money
  • Client was able to quickly shift focus onto more viable technologies
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