Continuous in vivo blood pressure measurements using a fully implantable wireless SAW sensor

Abstract

In this paper, the development of a fully implantable wireless sensor able to provide continuous real-time accurate pressure measurements is presented. Surface Acoustic Wave (SAW) technology was used to deposit resonators on crystalline quartz wafers; the wafers were then assembled to produce a pressure sensitive device. Excitation and reading via a miniature antenna attached to the pressure sensor enables continuous external interrogation. The main advantages of such a configuration are the long term stability of quartz and the low power necessary for the interrogation, which allows 24/7 interrogation by means of a hand-held, battery powered device. Such data are of vital importance to clinicians monitoring and treating the effects of hypertension and heart failure. A prototype was designed and tested using both a bio-phantom test rig and an animal model. The pressure traces for both compare very well with a commercially available catheter tip pressure transducer. The work presented in this paper is the first known wireless pressure data from the left ventricle of the heart of a living swine.

Miniature implantable telemetry system for pressure-volume cardiac monitoring

“…These systems range from creating a fully implantable cardiovascular pressure monitor with a medical stent [85] to a fully implantable blood pressure sensor for hypertonic patients [217]. Furthermore, much research has been placed on miniaturizing and improving the pressure sensor itself [197,215,218,219].…”

Wearable and Implantable Devices for Cardiovascular Healthcare: from Monitoring to Therapy Based on Flexible and Stretchable Electronics

“…Although soft wearable cardiovascular sensors are becoming more capable and long‐term, many localized and accurate electrophysiological signals still require in vivo measurement directly from the heart surface (Figure b, right) or the blood vessels (Figure b, left) …”

Recent Advances on Implantable Wireless Sensor Networks

“…Implantable wireless blood pressure sensors have been proposed in Ref. [30][31][32][33]. Blood pressure can also be useful to control vascular graft degradation through blood flow measurements, and a sensor capable of performing this task is presented in Ref.…”

“…Consequently, the resonant frequency of the coupled coils will shift as the parameter of interest, for example, IOP, varies. Generally, this approach requires no power from the implant [13,14,32,33,39,40], as the external reader is responsible to detect the impedance change in the implant's coil and, from it, calculate the sensed parameter's value. This allows for smaller implants, as power budget is reduced and no processing electronics are required.…”