A Through-Hole Capacitive Micromachined Ultrasonic Transdcuer with High Perfromance

Generally, CMUTs are composed of numbers of independent cells, whose edges are clamped on the posts. Such structure is characterized with high resonant frequency and high sensitivity. However, too much parasitic capacitance is often induced for the CMUTs because of the posts between cells, causing a low electromechanical coupling coefficient. At the same time, the collapse voltage is too high and does not have low power consumption characteristics. A through-hole CMUTs (TH-CMUTs) structure is proposed, which is clamped at the four corners of membrane. It has many advantages on the premise of ensuring the ultrasonic emission power and output current. Since the stiffness of TH-CMUTs structure is reduced, its collapse voltage can be greatly reduced. The original membrane on the post is suspended, then the original parasitic capacitance is transformed into the effective capacitance to increase the electromechanical coupling coefficient. Finally, the structure also has the characteristics of high filling ratio. All the advantages of proposed TH-CMUTs structure are simulated and validated.