An Ultrasound-Based Biomedical System for Continuous Cardiopulmonary Monitoring: A Single Sensor for Multiple Information

Abstract

In this paper, Lead Zirconate-Titanate (PZT)/Polydimethylsiloxane (PDMS) based composite is fabricated and characterized for its potential application as a flexible piezoelectric material. Thin films of the composite are prepared by dispersing different volume percentage of PZT particles in cross-linked PDMS matrix. Corona poling of the films is performed to increase the piezoelectric charge constant. X-ray diffraction results indicate that poling aligns the randomly oriented ferroelectric domains in the PZT particles along the poling axis. Piezoelectric voltage response and piezoelectric charge constant values before and after the poling show the improvement in piezoelectricity due to poling. The piezoelectric charge constant, d33 and magnitude of relative permittivity of the films increase and flexibility of the films decrease with the increase of PZT particle volume percentage in the composite. Results show that for 28 v% PZT composite poled film a d33 of 78.33 pC/N was achieved with a Youngs modulus of around 10 MPa and magnitude of relative permittivity of 10. The film demonstrates effectiveness for tactile sensing by generating charges across the film proportional to the finger pressure applied on them. The easy fabrication process makes the composite a promising candidate to build flexible low cost tactile sensing devices.

Contact and Remote Breathing Rate Monitoring Techniques: A Review

“…It is important when using ultrasound transducers to place the sensor away from the bones as they introduce both large attenuation factor and acoustic impedance of 5 dB/cm and 6 × 10 6 rayl, respectively [56]. The intercostal area among T5-T8 ribs offers a good resolution for monitoring both the heart and internal organs movement [55], [59]. The axial resolution of the sensor, hence, must be adjusted to accurately catch this range.…”

“…It is important when using ultrasound transducers to place the sensor away from the bones as they introduce both large attenuation factor and acoustic impedance of 5 dB/cm and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$6\times 10\,\,^{\mathrm{ 6}}$ \end{document} rayl, respectively [56] . The intercostal area among T5-T8 ribs offers a good resolution for monitoring both the heart and internal organs movement [55] , [59] . The axial resolution of the sensor, hence, must be adjusted to accurately catch this range.…”

“…An example of wearable ultrasound-based respiratory and heart rate system is shown in Fig. 11 [55] , [59] . In this implementation, a high-voltage (HV) pulser is employed to produce ±20 V with 1 MHz pulsed signal.…”

“…gel, which can cause some discomfort to the patient especially for prolonged monitoring. It is also sensitive to upper body movements and prone to error in cases of shallow breathing and obstructive sleep apnea [55] , [59] .

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Experimental Technologies in the Diagnosis and Treatment of COVID-19 in Patients with Comorbidities

“…Shahshahani et al utilized a single sensor for cardiac and respiratory monitoring via a different modality—ultrasounds by way of a PZT-4 piezo transducer [ 45 ]. The monitoring of cardiac changes is not limited to ECG or ultrasound, seismocardiography (SCG) also provides increased sensitivity for detecting anatomic and physiologic coronary artery disease.…”