Stripped down, high performance.
Chronic lung disease is the third most common cause of death in the world. Being prevalent in low-income countries, we saw the need for an affordable and easy way of delivering precise lung volume measurements.
Research & Ideation
There are several ways to measure lung volume. We studied the spirometers context of use and undertook stakeholder and user analysis to narrow down our research to three main technologies; differential pressure, turbine, and ultrasound.
As they all showed certain limitations we had to widened our exploration to discover the profitable vortex whistle that was taken forward due to its simplicity, accuracy, and cost.
The fundamental principle of vortex whistle spirometry is that the pitch of the sound produced is linearly proportional to the flow rate of fluid. The frequency of the pitch can be altered by changing the dimensions of the Inlet, outlet and the cavity of the whistle.
The initial design was produced using example values found in the research state of this technology.
By iterating through several 3D printed geometries it was found that, in general, smaller geometries produced higher pitched sounds.
Consequently, by reducing the size of the whistle the minimum frequency produced by the whistle was increased to a level which was above the general background sound.
We used MATLAB to record with the works-like prototype.
The aim was to produce a frequency against time graph for a recording taken from the built in microphone onboard the computer running the script. This would later be replaced by the more accurate and applicable external microphone.
We tested the final working prototype multiple times with a Sensirion Flow Meter to validate our results.
ERGONOMICS & FORM
After making a thorough design specification, model massing was used to get an understanding of the different overall shape, and to validated our belief that a vertical handle was not necessary, minimising the cost of material.
A rough CAD was created from conceptual sketches. Fast, low quality, 3D-prints were used to rapidly iterate the design after user testing. It was then made sure that the final works-like vortex whistle could be integrated in the looks-like prototype.
The final prototype was 3D-printing in ABS. The wanted surface finish was obtained by sanding down the 3D-print and applying a thin coat of spray paint, then sanding it down, then re-painting, over and over, creating a realistic surface finish. The prototype was then painted with the final coat and the logo was added.
The spirometer is simplified to a transducer (orange) and USB-C port (purple) and used with a computer, tablet or smartphone, displaying an instructive interface for patients, minimising the time needed for a nurse or doctor, who’s time is already in high demand.
By having a separate more powerful decide, it means all the processing, coaching, results and data bases can be stored on a common device. This eliminates the requirement for additional modules, keeping the entire product incredible cheap to manufacture and easy to upkeep.
The spirometers main body is split into two main components, exposing surfaces for easy cleaning, while shielding the electronic components.
As health and hygiene was a main consideration for our design specification, a stand was designed to house and keep the product clean in between uses as countertop surfaces might not be clinically clean in low-income settings.
Please note that this was a group project and not my sole work.
Fellow team members were Shivam Bhavnagar, Ben Greenberg and Kenza Zouitene.