Analysis and design of ultra-low power electronic circuits for body sounds monitoring

Abstract

Chronic Cardiorespiratory diseases such as Sleep Apnea, Asthma, Obstructive Pulmonary Disease (COPD) and Atrial Fibrillation affect more than 780 million across the world. These diseases have a big diverse effect on the quality of patients’ life and on the global economy as well. A major cause of these negative effects and economic burden is the traditional diagnoses method of these diseases, which suffer from many limitations. The main limitations are being expensive and not portable. To improve the detection and monitoring of these diseases and reduce their impact on the patients’ life, the idea of a remote diagnostic process for chronic respiratory and cardiac is proposed. The remote diagnostic process is composed of a wearable device that extracts the vital data of interest and algorithms that work on these data to extract disease related parameters that are useful in the diagnosis process. There is significant amount of work in the literature on different algorithms that extract different diseases related parameters from acoustic cardiorespiratory signals. However, there is a lack of true-low power devices to acquire these signals. This thesis presents the analysis, design, implementation and testing of a low-power wearable system that acquires and monitors the sounds of cardiac and respiratory activities. The system was designed from the transistor level and fabricated using AMS 0.18μ 6M layer technology. This makes it the first wireless acoustic sensor that is completely designed at the transistor level and thus achieves the lowest power consumption and smallest size compared to other works reported in the literature. The chip was directly wire-bonded on a custom made round shaped PCB that has 23mm diameter and integrated with a miniature MEMS microphone to create the final system. Lab measurements shows that the system achieves good functionality at less than 560μW supplied from 1.3V battery and can last on continuous operation for more than 2 weeks when supplied from a Zinc Air P13 battery.