Experimental Study of Millimetric Inclusions Detection Through a Spiral Contactless Sensor for Biomedical Applications

In this paper, the experimental results of a novel sensor for non-invasive millimeter inclusions detection are presented. The hardware configuration, working at 570 MHz, has been originally designed for air bubbles detection in hemodialysis, but it is suitable for several cases of target detection as well. The proposed microwave radiating system comprises a microstrip self-resonant spiral coil, inductively coupled to an external concentric and coplanar probe loop. An approach aimed at Q-Factor maximization has been followed to precisely achieve the spiral resonant design. In the proposed experimental set-up, we reproduced the blood tissue by using an Agar (2% w/v) solution, in which various millimetric PLA particles are embodied to simulate air inclusions. In particular, the inclusion detection is achieved by observing the external probe loop input impedance amplitude and frequency shift variation through VNA. Theoretical assumptions were validated by experimental results, encouraging future research into the sensor’s potential usage in biomedical applications. Indeed, the sensor might be employed to detect and real-time monitor the air inclusions and blood clots presence during a hemodialysis treatment, making the procedure safer for patients.