The aim of this thesis is to develop a prototype module which is capable of measuring carbon dioxide concentration of exhaled air.
The thesis introduces the development of a prototype instrument step-by-step: justification of the product and analyzing it’s field of use continued by collecting requirements of the system, comparing the possible solutions, separating the tasks into hardware and software part, performing the schematic and layout design for manufacturing, implementing firmware of the device and PC software, and finally testing of manufactured board.
The sensing of carbon dioxide concentration was performed using a sensor of type TPS2534G2/G20. This sensor is based on NDIR (Nondispersive Infrared Sensor) method which uses the property of carbon dioxide that it absorbs infrared light. The applied Atmage324A microcontroller performs the data acquisition: measures the pressure of the tube containing the exhaled air and the output signal of the carbon dioxide sensor, furthermore it sends these values to the PC. The software running on the computer analyzes, displays and saves the data received from the microcontroller.
The first part of the thesis gathers the necessary knowledge which also defines the basic requirements, and then the second part introduces the steps of realizing a hardware prototype as well as a PC software capable of testing the system.