the perfect dose

I learned the fundamentals of mechanical design in the medical device space while working at Triple Ring Technologies in Newark, California.

Brainstorming methods, materials selection, parameter optimization, constraints of machining and molding processes, design validation; an iterative process to systematically produce functional, elegant prototypes.

This bolus dose mechanism is an exemplar of these fundamentals at work: I created a novel mechanism which delivers a small but precise bolus dose of liquid drug to a patient from a wearable delivery device. In six months, we went from blank paper to a functional prototype that reduced dose variability from 6.6% to below 1.0% and was granted US Pat. 11007317.

This design was highly constrained in multiple dimensions: overall size, cost, force to actuate, ease of assembly, and above all, patient safety. I performed comprehensive static force balance analysis to correctly tolerance interference fits, drive sliding contact dimensions, and size the antagonistic springs which support dose and seal functions.

A micromachined rack and gear converts input translational motion into rotation of the mechanism, which loads and delivers a single dose when a user pushes into the rack. Wonderful - but how does design change when we build with soft matter and non-conventional fabrication technologies? I went back to grad school to find out.