An approach to durable poly(vinylidene fluoride) thin film loudspeaker

Abstract

The piezoelectric poly(vinylidene fluoride) (PVDF) surface possessing low surface energy was modified by the ion-assisted-reaction (IAR) method for the application of thin film speaker. The IAR-treated hydrophilic PVDF surface was investigated using atomic force microscopy and x-ray photoelectron spectroscopy. The adhesion strength between various types of electrodes and the film was dramatically improved due to the hydrophilic functional groups, such as –C–O–, –(C=O)–, –(C=O)–O–, and so forth. A durable loudspeaker film was fabricated by enhancing the adhesion between the screen-printed poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS) and the modified PVDF films. The PVDF speaker film with the PEDOT/PSS electrode showed higher durability, flatter sound pressure level characteristics, and easier processability compared to metals or indium tin oxide electrodes.

Improvement on frequency response characteristics of the ultra-thin piezoelectric acoustic actuators

“…In common with results from Figure 2, the measured resonant frequencies of the fabricated piezoelectric acoustic actuator before attaching the elastic mass were in excellent agreement with the simulated and measured results shown in Figure 1. However, after attaching the elastic mass to the vibrational diaphragm, the resonant frequencies which correspond to (2,2), (1,3) and (3,1) modes shifted from 1.12 kHz, 1.32 kHz and 2.24 kHz to higher frequencies of 1.5 kHz, 1.66 kHz and 2.68 kHz, respectively. These results can be described by the reason that the elastic mass attached to the acoustic diaphragm has the same shape with (3,1) mode so that can purposely disturbs the vibrations at (2,2) and (1,3) modes by stiffening the acoustic diaphragm at those modes.…”

“…Thus, it is obvious that the attached elastic mass greatly influence on the vibrational characteristics of the piezoelectric acoustic actuator. For (1,3) and (3,1) modes, the elastic mass attached to the acoustic diaphragm shifted the resonant frequencies to higher values as well as remarkably reduced the displacement performance. In addition, the significant peak and dip in sound pressure of piezoelectric acoustic actuator can be also reduced by attaching the elastic mass to the acoustic diaphragm, which enhance the acoustic frequency response characteristics.…”

“…Recently, piezoelectric acoustic actuators have attracted a great deal of attention for ultra-slim portable electronic devices because of their obvious benefits of being thinner, more powerefficient and lighter than the traditional dynamic speakers [1]- [4]. While the traditional moving-coil speakers are usually thicker than 3 mm, the ultra-thin piezoelectric acoustic actuators can be thinner than 1 mm because they do not need any thick permanent magnet.…”

Nanotribology of polyvinylidene difluoride (PVDF) in the presence of electric field

“…PVDF has excellent flexibility, biocompatibility, thermal stability, lightweight, conformability, low cost, and low acoustic and mechanical impedance, making it a favorable material for various applications, such as a transducer [15], a loudspeaker [23], a supercapacitor [16], an ultrasonic motor [30], and an electric power generator [21]. It is also possible for PVDF to be used as an artificial hip joint due to its biocompatibility [13].…”

Low-frequency reinforced ferroelectric acoustic actuators

“…In order to achieve these demands of the system, a number of researches for alternatives to traditional components have been presented [1]- [5]. Among them, ferroelectric acoustic actuators or piezoelectric ceramic speakers have received a lot of attention as the most promising devices to overcome limitation of technologies [6]- [8].…”