Case Study

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
  • Resulted in FPrin conceiving of a “Plan B” – an alternative pump architecture that moved these key metrics to meet requirements
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