Microwave stethoscope: A new method for measuring human vital signs

A new microwave method for human vital signs measurements is described. The method is based on reflection coefficient measurements, thus realizing the microwave stethoscope vision, and the use of DSP algorithms for extracting vital signs. A unique microwave coupler/sensor with good impedance matching to human skin is designed and the developed measurement procedure is verified experimentally using phantom models. Obtained results demonstrated the ability to extract parameters such as breathing rate, heart rate, and lung water content from a single microwave measurement. Results from this new approach are also compared with a previously described transmission coefficient measurement-based method. It is shown that while the transmission measurements provide more sensitivity, the reflection coefficient based results are also accurate and received signal/noise levels are well within the capabilities of the developed DSP algorithms. Results from the phantom experiment as well as from experimental data from a dog experiment are used in this comparative study. The proposed experimental procedure as well as the experimental and DSP extracted vital signs results will be presented.