Dual-electrode CMUT with non-uniform membranes for high electromechanical coupling coefficient and high bandwidth operation

Abstract

In this paper, we report measurement results on dual-electrode CMUT demonstrating electromechanical coupling coefficient (k2) of 0.82 at 90% of collapse voltage as well as 136% 3 dB one-way fractional bandwidth at the transducer surface around the design frequency of 8 MHz. These results are within 5% of the predictions of the finite element simulations. The large bandwidth is achieved mainly by utilizing a non-uniform membrane, introducing center mass to the design, whereas the dual-electrode structure provides high coupling coefficient in a large dc bias range without collapsing the membrane. In addition, the non-uniform membrane structure improves the transmit sensitivity of the dual-electrode CMUT by about 2dB as compared with a dual electrode CMUT with uniform membrane.

Radiation impedance of collapsed capacitive micromachined ultrasonic transducers

“…where Z ij nm is the mutual impedance between the ith and jth transducers having the velocity profiles v n (r) and v m (r) in (3). Z ij nm is given by Porter [29] as an infinite summation.…”

“…Introduction c apacitive micromachined ultrasonic transducers (cMUTs) [1], [2] have been of interest because of their wider bandwidth compared with piezoelectric transducers [3]. Medical imaging [4]- [6], high-intensity focused ultrasound (HIFU) treatment [7], [8], and intravascular ultrasound (IVUs) [9]- [11] are just a few of the application areas where they are currently being considered as a promising technology.…”

Radiation impedance of an array of circular capacitive micromachined ultrasonic transducers in collapsed state

“…Capacitive micromachined ultrasonic transducers (CMUTs) have drawn attention due to wide bandwidth they present especially when immersed in water [1]. Two available tools for the design and optimization of CMUTs are finite element method (FEM) simulations and electrical equivalent circuit approach.…”

Wafer bonded capacitive micromachined underwater transducers

“…It's been demonstrated that CMUTs offer excellent properties such as wide bandwidth [2], ease of array fabrication and integrating the dedicated electronics along with the transducers, [3] thanks to the microfabrication techniques utilized during fabrication. Recent studies show that high power outputs can be obtained [4] and high receive sensitivities can be achieved using CMUTs [2].…”

“…Recent studies show that high power outputs can be obtained [4] and high receive sensitivities can be achieved using CMUTs [2]. CMUT's large bandwidth, high sensitivity, low cost fabrication and ease of integration with electronics make it a good candidate for an underwater transducer.…”