Microwave and Contactless Sensor for Millimeter Inclusions Detection in Biomedical Applications

In this paper, we present an innovative sensor for non-invasive detection of millimeter inclusions by using a microwave radiating system. The proposed device consists in a microstrip self-resonant spiral coil inductively coupled to an external concentric planar probe loop, working at a frequency of 570 MHz. The microwave sensor configuration is the result of an optimization process of the spiral coil Q-factor maximization, required to obtain a millimeter resolution for the inclusions detection. In particular, the detection is achieved by observing the amplitude and frequency shift variation of the external planar probe input impedance. We performed full-wave simulations to design and evaluate the radiating system performance. Numerical results validated the introduced theorical approach, encouraging further analysis for the potential use of such sensor in biomedical applications. Indeed, the radiating device can be extremely useful in all the tasks where it is required to spot the presence of undesired and dangerous impurities in a contactless way. For instance, the sensor might be employed to detect and monitor in real-time the presence of air inclusions and blood cloths during a hemodialysis treatment, making the procedure safer for patients.