Design, Manufacture and Validation of a Spirometry Device aimed for Low-Resource Settings

Background: Medical devices are essential for maintaining resilient health systems worldwide. However, their distribution does not reflect this, with as many as 76% of devices being used by 13% of the world’s population. Most devices, being designed for high-income countries and failing to consider the local needs of other settings, often fail when deployed in other contexts. A frugal approach can be used to design more resilient systems. Spirometers show promise for developments in this area, owing to the high burden of respiratory conditions in low- and middle-income countries and the unavailability of frugal versions that can enable local care in such settings. Therefore, this work aims to develop an affordable spirometer for low-resource settings. Methods: A frugal approach was used to design a Venturi-style spirometer based on Bernoulli’s principles, leveraging 3D-printed parts and components such as an Arduino Uno R3 and differential pressure sensor (MXP5010DP). The accompanying software to process the signal and calculate relevant variables was developed on Arduino IDE and MATLAB. The device was validated via a hand-pump test and with an initial usability study on two subjects together with a CE-marked benchmark. The mean signed percentage error was then calculated to evaluate accuracy. To determine whether the input flow affected the measured volume Spearman’s rho and p values were calculated. Results: The device was successfully 3D printed from PLA, and then assembled with electronic components. All the software functioned as expected when it was run. In the two-litre pump test, the device achieved a mean reading of 1.983 L (true value 2L) and an accuracy of 1.53% (mean absolute percentage error). The Spearman’s Rho test revealed that there was no significant correlation between flow speed and volume. In the usability study, the device achieved readings similar to those of the CE marked device, and all values fell within normative values. Conclusions: This study designed, prototyped and validated a spirometer that can be used as a lung screening tool that achieves high accuracies comparable to those of other portable spirometers. This study also validated that frugal engineering could reduce the cost of devices without affecting the clinical accuracy.