Future of smart cardiovascular implants

Cardiovascular disease remains the leading cause of death in Western society. Recent technological advances have opened the opportunity of developing new and innovative smart stent devices that have advanced electrical properties that can improve diagnosis and even treatment of previously intractable conditions, such as central line access failure, atherosclerosis and reporting on vascular grafts for renal dialysis. Here we review the latest advances in the field of cardiovascular medical implants, providing a broad overview of the application of their use in the context of cardiovascular disease rather than an in-depth analysis of the current state of the art. We cover their powering, communication and the challenges faced in their fabrication. We focus specifically on those devices required to maintain vascular access such as ones used to treat arterial disease, a major source of heart attacks and strokes. We look forward to advances in these technologies in the future and their implementation to improve the human condition

Implantable telemetry for small animals

A series of totally implantable telemetry devices for use in measuring deep body parameters in small animals were developed. Under a collaborative agreement with NASA, several of these systems; the continuous wave Doppler ultrasonic flowmeter, the multichannel telemetry system, and the inductively-powered dual channel cardiac pacer were evaluated in a series of ten mongrel dogs (15 to 20 kg.). These systems were used to measure ascending aortic and coronary blood flow, aortic pressure, and subcutaneous EKG

Low Power Circuits for Smart Flexible ECG Sensors

Cardiovascular diseases (CVDs) are the world leading cause of death. In-home heart condition monitoring effectively reduced the CVD patient hospitalization rate. Flexible electrocardiogram (ECG) sensor provides an affordable, convenient and comfortable in-home monitoring solution. The three critical building blocks of the ECG sensor i.e., analog frontend (AFE), QRS detector, and cardiac arrhythmia classifier (CAC), are studied in this research. A fully differential difference amplifier (FDDA) based AFE that employs DC-coupled input stage increases the input impedance and improves CMRR. A parasitic capacitor reuse technique is proposed to improve the noise/area efficiency and CMRR. An on-body DC bias scheme is introduced to deal with the input DC offset. Implemented in 0.35m CMOS process with an area of 0.405mm2, the proposed AFE consumes 0.9W at 1.8V and shows excellent noise effective factor of 2.55, and CMRR of 76dB. Experiment shows the proposed AFE not only picks up clean ECG signal with electrodes placed as close as 2cm under both resting and walking conditions, but also obtains the distinct -wave after eye blink from EEG recording. A personalized QRS detection algorithm is proposed to achieve an average positive prediction rate of 99.39% and sensitivity rate of 99.21%. The user-specific template avoids the complicate models and parameters used in existing algorithms while covers most situations for practical applications. The detection is based on the comparison of the correlation coefficient of the user-specific template with the ECG segment under detection. The proposed one-target clustering reduced the required loops. A continuous-in-time discrete-in-amplitude (CTDA) artificial neural network (ANN) based CAC is proposed for the smart ECG sensor. The proposed CAC achieves over 98% classification accuracy for 4 types of beats defined by AAMI (Association for the Advancement of Medical Instrumentation). The CTDA scheme significantly reduces the input sample numbers and simplifies the sample representation to one bit. Thus, the number of arithmetic operations and the ANN structure are greatly simplified. The proposed CAC is verified by FPGA and implemented in 0.18m CMOS process. Simulation results show it can operate at clock frequencies from 10KHz to 50MHz. Average power for the patient with 75bpm heart rate is 13.34W

Low Power CMOS Electrocardiogram Amplifier Design for Wearable Cardiac Screening

The trend of health care screening devices in the world is increasingly towards the favor of portability and wearability. This is because these wearable screening devices are not restricting the patient’s freedom and daily activities. While the demand of low power and low cost biomedical system on chip is increasing in exponential way, the front-end electrocardiogram (ECG) amplifiers are still suffering from flicker noise for low frequency cardiac signal acquisition, 50Hz power line electromagnetic interference, and the large unstable input offsets due to the electrode-skin interface is not attached properly. In this paper, a CMOS based ECG amplifier that suitable for low power wearable cardiac screening is proposed. The amplifier adopts the highly stable folded cascode topology and later being implemented into RC feedback circuit for low frequency DC offset cancellation. By using  0.13µm CMOS technology from Silterra, the simulation results show that this front-end circuit can achieve a very low input referred noise of  1pV/Hz1/2 and high common mode rejection ratio of 174.05dB. It also gives voltage gain of 75.45dB with good power supply rejection ratio of 92.12dB. The total power consumption is only 3µW and thus suitable to be implemented with further signal processing and classification back end for low power wearable biomedical device

SENSING MECHANISM AND APPLICATION OF MECHANICAL STRAIN SENSOR: A MINI-REVIEW

This study reviews the potential of flexible strain sensors based on nanomaterials such as carbon nanotubes (CNTs), graphene, and metal nanowires (NWs). These nanomaterials have excellent flexibility, conductivity, and mechanical properties, which enable them to be integrated into clothing or attached to the skin for the real-time monitoring of various activities. However, the main challenge is balancing high stretchability and sensitivity. This paper explains the basic concept of strain sensors that can convert mechanical deformation into electrical signals. Moreover, this paper focuses on simple, flexible, and stretchable resistive and capacitive sensors. It also discusses the important factors in choosing materials and fabrication methods, emphasizing the crucial role of suitable polymers in high-performance strain sensing. This study reviews the fabrication processes, mechanisms, performance, and applications of stretchable strain sensors in detail. It analyzes key aspects, such as sensitivity, stretchability, linearity, response time, and durability. This review provides useful insights into the current status and prospects of stretchable strain sensors in wearable technology and human–machine interfaces

Aerospace medicine and biology: A continuing bibliography with indexes, supplement 183

This bibliography lists 273 reports, articles, and other documents introduced into the NASA scientific and technical information system in July 1978

Low noise and low power ECG amplifier using cmos 0.13μm technology

Through the scaling down of modern VLSI technologies, the realization of CMOS based electrocardiogram (ECG) device becoming wearable to its user is possible. Yet, this transition introduces more constraints to its analog circuits. This is due to the measured electrical signal of ECG devices, or known as ECG signal possessed characteristics that are low in frequency (0.1 to 150Hz) and amplitude (<5mV), thus it lead to every ECG devices suffered from flicker noise for low frequency cardiac signal acquisition at the front-end of its sensor, 50 Hz power line electromagnetic interference, and the large unstable input offsets due to the improper attachment of electrode-skin interface. Therefore, to encounter this problem, the frontend of ECG devices, which is amplifier needed to be enhance so it able to accurately detect the ECG signals. Besides that, the amplifier must able to operate at low voltage and less power consumption so that it can be used in wearable device. In this work, a high performance CMOS amplifier for ECG sensors that improves the noise issue and suitable for low power wearable cardiac screening is designed. The designed circuit adopts the folded cascode topology to achieve high gain and less susceptible to noise. This work uses 0.13 μm CMOS process technology from Silterra and Mentor Graphics Pyxis as the design tool. This successfully achieve high CMRR which is 160dB. Besides that, this work also able to reduce the noise at the front-end amplifier system down to 1.28nV/√Hz. The power consumption of the designed amplifier is 3 μW, which is low and suitable to be implemented on design for wearable ECG devices

Wearable System for Biosignal Acquisition and Monitoring Based on Reconfigurable Technologies

Wearable monitoring devices are now a usual commodity in the market, especially for the monitoring of sports and physical activity. However, specialized wearable devices remain an open field for high-risk professionals, such as military personnel, fire and rescue, law enforcement, etc. In this work, a prototype wearable instrument, based on reconfigurable technologies and capable of monitoring electrocardiogram, oxygen saturation, and motion, is presented. This reconfigurable device allows a wide range of applications in conjunction with mobile devices. As a proof-of-concept, the reconfigurable instrument was been integrated into ad hoc glasses, in order to illustrate the non-invasive monitoring of the user. The performance of the presented prototype was validated against a commercial pulse oximeter, while several alternatives for QRS-complex detection were tested. For this type of scenario, clustering-based classification was found to be a very robust option.This work was funded by Banco Santander and Centro Mixto UGR-MADOC through project SIMMA (code 2/16). The contribution of Víctor Toral was funded by the University of Granada through a grant from the “Iniciación a la investigación 2016” program. The contribution of Antonio García was partially funded by Spain’s Ministerio de Educación, Cultura y Deporte (Programa Estatal de Promoción del Talento y su Empleabilidad en I+D+i, Subprograma Estatal de Movilidad, within Plan Estatal de Investigación Científica y Técnica y de Innovación 2013-2016) under a “Salvador de Madariaga” grant (PRX17/00287). The contribution of Francisco J. Romero was funded by Spain’s Ministerio de Educación, Cultura y Deporte under a FPU grant (FPU16/01451). The contribution of Francisco M. Gómez-Campos was funded by Spain’s Ministerio de Economía, Industria y Competitividad under Project ENE2016_80944_R

Design and experimental validation of a stress- controlled pressure sensor for wearable pulse monitoring

This paper presents a pulse sensor design scheme with adjustable preset pressure. The design consist of two PVDF layers sandwiching a PZT layer. While PZT is used to detect the pulse vibrations, PVDF layers are employed to adjust the pressure load on PZT. This enables more reliable and repeatable pulse wave measurements every time the sensor is worn on the skin. A basic design and an I-shaped design are simulated on COMSOL software under Piezoelectric Device module to show maximum performance that can be achieved under same pressure conditions. Off-the-shelf components were used for testing the sensor designs under the same externally applied load. The I-shaped design was shown to outperform the basic sensor design in both simulations and test results. This design can be employed in the development of reliable and repeatable pulse sensors, and poses significant potential in measuring the blood pressure.No sponso