Fully Wireless Implantable Cardiovascular Pressure Monitor Integrated with a Medical Stent

Abstract

This paper presents a fully wireless cardiac pressure sensing system. Food and Drug Administration (FDA) approved medical stents are explored as radiating structures to support simultaneous transcutaneous wireless telemetry and powering. An application-specific integrated circuit (ASIC), designed and fabricated using the Texas Instruments 130-nm CMOS process, enables wireless telemetry, remote powering, voltage regulation, and processing of pressure measurements from a microelectromechanical systems (MEMS) capacitive sensor. This paper demonstrates fully wireless-pressure-sensing functionality with an external 35-dB.m RF powering source across a distance of 10 cm. Measurements in a regulated pressure chamber demonstrate the ability of the cardiac system to achieve pressure resolutions of 0.5 mmHg over a range of 0-50 mmHg using a channel data-rate of 42.2 kb/s.

Experimental Path Loss Models for In-Body Communications within 2.36-2.5 GHz

“…These transmission ranges are suitable for some communication applications in the thoracic cavity, e.g., wireless sensing for a subcutaneous implantable cardioverter-defibrillator (s-ICD) [35], [36]. An implanted cardiovascular pressure monitor integrated with a medical stent [37] could send an alert signal on a wireless interface within 2360-2483.5 MHz to the s-ICD in order to deliver transthoracic shocks when ventricular tachyarrhythmias are detected.…”

Precision in harsh environments

“…However, use of silicon allows a number of sensors to be included on a single chip 100,101 . As stated above, catheters are generally used over periods of o 72 h and maintain direct wired contact to the outside world, but implanted sensors often must remain in the body for longer periods and use wireless communication 102,103 . In addition, power for the devices must be considered.…”

Implantable Sensor System for Remote Detection of a Restenosis Condition

“…In this field, three approaches have been proved to be compatible with e-stent design: electromagnetic, ultrasonic and pressure-based techniques [3][4][5]. Pressure-based techniques are of special interest, because of their simple implementation, low power requirements, reduced dimensions and integration capabilities of sensors and electronic circuits on the same silicon substrate.…”

“…An intelligent stent (e-stent) that incorporates a sensor and integrated electronic circuitry, capable of monitoring and transmitting real-time measurements of physiological parameters related to blood vessel occlusion, such as pressure and flow velocity, can be a useful tool to ISR early detection [3][4][5].…”