We have developed a method to perform impedance measurement using general purpose smartphones that will not require the presence of external power source. The need for battery-less impedance sensing methods is greatly demanded given recent years’ advancements in impedance based sensing technologies, such as impedance tomography, which will enable patients to perform medical tests such as breast cancer self-detection using only a smartphone.
The work discussed in this thesis is an early prototype of the impedance sensing method done using MATLAB simulation of both hardware and algorithm for impedance sensing. The battery-less acoustic impedance sensing technique is a combination of both hardware circuit design as well as control software algorithm. The circuit hardware technology is based on the additive summing mixer technology that is widely used in professional audio production mixing consoles. The results presented in this thesis can be accurate to within 0.1% of target device characteristics in simulation as far as tested.
Although not discussed in this work, in our early physical hardware prototypes, the measurement based on the method discussed in this thesis has achieved accuracy within 10% of the target value with all the noise and parameter approximations
