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Real-time Signal-to-noise Optimization of Bio-impedance Signal for Cuffless Blood Pressure Monitoring
No full textBlood pressure (BP) monitoring is essential as high BP is a major risk related to cardiovascular disorders (CVD). Continuous BP monitoring provides significant advantages in predicting future cardiovascular disease over traditional BP measurement methods. Traditional BP measurement methods are based on an inflatable cuff which is bulky, invasive, and inconvenient for true continuous monitoring. Within the method of continuous BP monitoring, the measurement of pulse transit time (PTT) is essential to estimating BP over time. PTT is the time taken for a pressure pulse to travel between two points in an arterial vessel, which is correlated with BP. This is mainly accomplished through bio-impedance sensors that monitor the arterial pressure pulse from the blood volume changes at the sensor site which result in impedance changes that can be read through the bio-impedance sensors. These small impedance changes from the body, along with a carrier signal from current injected into the body, generate amplitude modulated signals that can be digitally processed in real-time to produce bio-impedance signals. The bio-impedance sensors can be placed on the wrist, in-line with the radial and ulnar arteries and can be incorporated into a wrist-worn device such as a smart watch to provide a truly continuous BP monitoring device. However, the quality of the bio-impedance signal from each sensor is significant to the accuracy of PTT and the estimation of BP. For the device to be wearable for any user, placement of sensors over the arteries and contact quality between the electrodes and skin may not be optimal. This can lead to high skin-electrode impedance which can cause saturation of the current injection module of the device. This results in need to set the current injection signal���s amplitude to be a fixed low value and degrades the signal-to-noise ratio and overall signal quality. In this research, we present an automatic gain control (AGC) circuit as a method of increasing the signal-to-noise ratio of bio-impedance signals for the cuffless BP monitoring device. AGC senses the skin-impedance and determines the need to increase or decrease current injection through the body to ensure injection of maximum current to maximize the signal-to-noise ratio while avoiding saturation of the current injection module. In this research, data was collected through a custom calibration board that models skin-impedance and with participants using our custom low-noise bio-impedance sensing hardware. AGC efficiently increases signal-to-noise ratio of the bio-impedance signals which leads to better estimation of blood pressure
Thrifted Religion: Essays on Finding Religion in Texas Thrift Stores
No full texteBook, student & faculty research collaborationThis book is a collection of select essays written by TAMU students in the COMM 480: Religious Communication course in Spring 2024. Each student in the class became a research collaborator in the "Thrifting Religion" research project run by Dr Heidi A Campbell. This project documents and studies the different forms of ���religious material culture��� found through secondhand sales and resale shops. Religious material culture refers to the study of physical objects related to the beliefs and practices of various religions (i.e. prayer beads, religious jewelry, holy books, etc.). Students were asked to select an item from this collection and then write a short report about what that object is, how it is used in religious practices, and what messages about religion the items appeared to communicate. The best essays from the class are featured here, and they tell the story of how religions becomes represented, commodified, and incorporated in unique ways into people's everyday religious life.This book is part of the Thrifted Religion Exhibition that has been funded by the Academy for the Visual Arts and the Sciences at Texas A&M University
