The COVID-19 pandemic has taken a massive toll on medical infrastructure, and this was especially true at the inception of this project. In response, one of the main things that I worked on for my research at the Fluid Interactions Lab at USC Viterbi was the development of a low cost 3D printable spirometer that could shore up medical device shortages.

What is a Spirometer?

Spirometers are devices that measure lung function in patients, typically in terms of airflow volume. There are multiple forms of them- however, generally digital spirometers are preferred for their ability to interpret data and more accurately describe patient condition and recovery. These digital spirometers are very expensive when compared to the fundamentals of what they're trying to accomplish.

Video Overview of the Project

Embedded below is a short video where I outline the basics of what I was able to accomplish in my research this summer.

Thinking Big Picture About Cutting Costs

First, I want to address the macroeconomic factors that support the concept of 3D printing medical devices. Medical devices typically fall into the category of inelastic products, since supply and demand ideally has a limited effect on the cost. The COVID-19 pandemic has not driven up the cost of these machines, rather, it has driven up the price: centralizing medical infrastructure and rapidly responding to a pandemic is a logistical nightmare, and this is reflected in the amount of money spent on the medical supply chain. Regardless of the actual price of the machines, people pay as much as is needed to actually get them from the production line to  the hospital, from the hub to the spoke. I completely believe that 3D printing components changes the game. A future where hospitals around the world are able to react instantly to changes on a global scale can be facilitated by 3D printers. 3D printing is a way to decouple the cost of medical machines from the actual price of logistically making them available. 

Cost From a Design Perspective

My spirometer design takes complete advantage of the ability to 3D print geometry that would otherwise be difficult, expensive, or impossible with more mainstream techniques such as injection molding, vacuum forming, or subtractive processes. Simplicity is the name of the game with my design: the whole chassis is printed in a single nonmoving part. I accomplished this through the use of an aerodynamic principle known as the venturi effect. Taking advantage of these properties allows the entire chassis of my device to cost slightly under 2 dollars (calculated from filament mass).

Software

I didn't mention computers in the previous paragraph, so you can almost get a picture of me furiously writing equations as the spirometer beeps away, but this was definitely not the case: the biggest and most time consuming piece of the project was without a doubt the software component. Prior to this project, my experience with coding and software development was limited to brief work on rocket flight computers. That's to say that I knew a lot of the terms, but I didn't really know how to execute my ideas in code. There was a massive amount of trial and error throughout the process, but by the end of it, I successfully learned how to port in data, interpret this data through a series of conditions, and then filter the data using some new calculus techniques I picked up.