P3Q-2 Development and Evaluation of a 20MHz Array for Ultrasonic Detection of Middle Ear Effusion

This paper presents the design and acoustical testing of a 20 MHz 2D array for non-invasive detection and characterization of middle ear effusion, as well as results of the clinical study performed with this probe. The transducer is a 3times3 element, 400 mum pitch array and operates at 20 MHz center frequency. It is shaped with a 3 mm radius spherical convex surface. The piezoelectric material is based on 1-3 piezocomposite technology and front layer is optimized. The probe is placed on the tip of 3 mm outer diameter tubing and interfaced to a pulsing system. The challenging manufacturing process of the whole transducer is here reviewed, as well as the electro-acoustical characteristics including sensitivity, frequency range and homogeneity. Clinical exams were performed by non-invasively introducing the probe into the external auditory canal. The condition of the middle ear was determined by the analysis of ultrasonic echoes collected from the tympanic membrane and middle ear cavity. The spherical geometry of the probe allowed easy positioning of one element of the array perpendicular to the reflecting surface (tympanic membrane) and thus obtain optimal ultrasonic echoes. The clinical results achieved with the probe show the significant value of this technique for detection and characterization of middle ear effusion in children