Design of a lung function testing device

A lot of useful information about the mechanical behavior of lungs during health and disease can be obtained using the forced oscillation technique (FOT). This technique measures the respiratory impedance by applying pressure waves P at the mouth of the patient and measuring the resulting air flow response Q. Commercial devices using this technique are currently available but are limited in the frequency range at which they can measure the respiratory impedance. Animal testing has shown that a lot of extra information can be obtained by measuring at low frequencies (0.1-10 Hz).


In this thesis you will contribute to the improvement of a device that can measure at these low frequencies. A setup using ventilators controlled by a PIC32 microcontroller is already operational (see below). This setup can generate pressure waves at frequencies between 0.1 and 4 Hz while the patient is breathing.


Fig.: Ventilator setup

The goal is to extend this setup with a set of speakers in order to develop a device that can measure from 0.1 to 20 Hz during patients breathing. To obtain this goal, the following challenges need to be tackled:

  1. Generation of a broadband pressure wave between 5 and 20 Hz using only the speakers.
  2. Tuning of this broadband pressure wave using the PIC32 Microcontroller.  
  3. Assemble the speaker and ventilator setup in order to generate a pressure wave with excited frequencies between 0.1 and 20 Hz.

During this process you will be able to add your own ideas to enhance the operation of the device. 

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