“Pipe Organ” Inspired Air-Coupled Ultrasonic Transducers With Broader Bandwidth

Abstract

Piezoelectric micromachined ultrasonic transducers (PMUTs) are used to receive and transmit ultrasonic signals in industrial and biomedical applications. This type of transducer can be miniaturized and integrated with electronic systems since each element is small and the power requirements are low. The bandwidth of the PMUT may be narrow in some conventional designs; however, it is possible to apply modified structures to enhance this. This paper presents a methodology for improving the bandwidth of air-coupled PMUTs without sensitivity loss by connecting a number of resonating pipes of various lengths to a cavity. A prototype piezoelectric diaphragm ultrasonic transducer is presented to prove the theory. This novel device was fabricated by additive manufacturing (3-D printing), and consists of a polyvinylidene fluoride thin film over a stereolithography designed backplate. The backplate design is inspired by a pipe organ musical instrument, where the resonant frequency (pitch) of each pipe is mainly determined by its length. The -6-dB bandwidth of the "pipe organ" air-coupled transducer is 55.7% and 58.5% in transmitting and receiving modes, respectively, which is ~5 times wider than a custom-built standard device.

FLAUT: A mutual sensitivity improvement through matched pipe, cavity and thin plate resonance

“…This design features a backplate with an array of consecutive concentric cavity and pipes as shown in Figure 3. This is contrary to the single cavity and multiple acoustic relief pipes design in condenser microphone as discussed by Tan and Miao [16] and Lavergne et al [19]; which are then adapted by Zhu et al into a single cavity and multiple pipes design [18].…”

“…The device design is similar to the typical condenser microphone previously discussed, except on the design and construction of the acoustic relief. Further, Zhu et al [18], have validated through experiments that having single cavity and a backplate of 13 individual acoustic relief holes connected to acoustic amplifying pipes have a normalized transmitting voltage response (TVR) of 4.6 times larger than standard device with -6 dB bandwidth. Repeatability of the experiments indicates that the fabrication and measurement are repeatable using the additive manufacturing process.…”

Piezoelectric Micromachined Ultrasonic Transducer-Integrated Helmholtz Resonator with Microliter-Sized Volume-Tunable Cavity

“…Some approaches to assembling the ultr2asonic transducer with the Helmholtz resonator structure and enhancing the performance of ultrasonic emission have been based on the actuator being attached to the cavity portion of the Helmholtz resonator. Although this configuration could increase the operation bandwidth compared with using the resonator cavity without a neck portion, the reduced pressure magnitude may be a shortcoming [ 18 ].…”

Additive Manufacturing (AM) Capacitive Acoustic and Ultrasonic Transducers Using a Commercial Direct Light Processing (DLP) Printer

“…MEMS microphones can achieve reasonable sensitivity at low bias voltages due to their narrow air-gaps [2]. Many researchers have proposed several transducer or microphone designs with complex 3D structures in order to explore different ways to enhance their performance such as sensitivity [3] [4], bandwidth [5], [6] and directivity [7]. In recent years, there has This paragraph of the first footnote will contain the date on which you submitted your paper for review.…”