Smartphone Capnography : Evaluation of the concept and the associated CO₂ indicating sensor

Sammanfattning:

Smartphone capnography is a new concept for respiratory monitoring using a colorimetric sensor in combination with a smartphone and an Android application. Compared to using an infrared spectrophotometric carbon dioxide analyzer (IR-analyzer), the gold standard for respiratory carbon dioxide monitoring, smartphone capnography offers a cheaper and less bulky solution. This master thesis evaluates the performance of smartphone capnography and the colorimetric sensor engineered for this concept. Three different techniques (side stream, shunt stream and main stream) were tested. Additionally, an iPhone application was developed as a proof of concept when using an iPhone for smartphone capnography.

An experimental set-up simulating human breathing was assembled and measurements, at different breathing rates (6-30 breaths/min) and carbon dioxide levels (2-7vol%), were performed with an IR-analyzer as reference. Results showed that capnograms from smartphone capnography was comparable to those from the IR-analyzer and that the approximate accuracy was ±0.25vol% for up to 6 days of use. Results strongly motivate further elaboration of the concept and the three different techniques for measuring.