| dc.description.abstract | Ultrasound imaging has become one of the most widely used diagnostic tools because it is safe, less expensive, produce real time image. Ultrasound technology has been widely used for a broad range of applications including medical imaging. An ultrasound transducer is one of the most important components in a medical ultrasound imaging system. This device interacts with the human body by creating the sound waves and receiving the echoes. An ultrasonic array transducer is a single transducer that contains a number of individually connected elements. Recent years have seen a dramatic improvement in the use of ultrasonic array transducers for medical applications. Variations of the individual elements from their ideal state will have significant effects on the performance of the linear array transducers. The aim is to design, fabricate and test a prototype dual frequency ultrasound array. The array shall be based on an acoustic stack with two piezoelectric layers, one „pumping‟ low frequency at around 4 MHz, and one „imaging‟ high frequency, around 20 MHz. This thesis studies the design and characteristic of both the transducer array. Piezoelectric material i.e. (Pzt-27) has been used as an active layer for 4 Mhz transducer and Fuji c-82 has been used as an active layer for 20 Mhz transducer. Performance parameters of importance in transducer design are considered, including sensitivity, coupling constant, band width, frequency downshift beam and electrical matching. Impedance measurement for the both transducer has been measured and compared. | nb_NO |
