Integrated Wireless RFID Temperature Sensor for Biological Aortic Valve Prostheses

Body core temperature is one of the most reliable biometric indicators for monitoring the health status of a person. The gold standard in clinical settings is a highly invasive procedure involving the insertion of a catheter into the pulmonary artery, which receives blood directly from the core of the body. However, if a patient needs to host an Implanted Medical Device (IMD), a precise body core temperature measurement can be obtained without causing them additional discomfort, by adding communication and sensing capability to the IMD itself. This paper proposes a possible augmentation of a passive metal-free aortic valve prosthesis with a wrapped C-dipole provided by an RFID-based temperature sensor for batteryless and wireless temperature monitoring from the inside. A robust transcardiac link can be achieved with at least 24 dBm interrogation power by using a small on-skin reader antenna, which is also robust against moderate mutual misalignment among the two devices. The temperature sensing capability of a true sensorized valve, evaluated by means of a heated liquid phantom, demonstrated the possibility of sensing typical physiological temperature gradients with an average accuracy of less than 0.25 °C w.r.t. a reference thermocouple.