In this study, we obtained and characterized a composite film made of lead zirconate titanate (PZT) piezoelectric ceramic and non-polar polyvinylidene fluoride (α-PVDF) as a functional material. The scanning electron microscopy (SEM) results show this composite film to have mixed connectivity due to the agglomeration of some of the PZT particles. The response of the composite to an applied ac voltage at 4110 Hz has a slope of 0.074 nm/V. The measured displacement is in the range of 0-30 nm for electric voltages ranging from 0-400 V. The experimental results show the composite performance as an acoustic emission (AE) sensor to be good agreement with the response of a commercial standard microphone in the frequency range of 2-6 kHz. By applying 2 kN of cyclic force at a frequency of 3 Hz, we obtained an 80 V peak signal and calculated a dissipated power equal to 158 μW.

In this paper, we report on the development of an intensity-modulated fiber-optic sensor for angular displacement measurement. This sensor was designed to present high sensitivity, linear response, and wide bandwidth and, furthermore, to be simple and low cost. The sensor comprises two optical fibers, a positive lens, a reflective surface, an optical source, and a photodetector. A mathematical model was developed to determine and simulate the static characteristic curve of the sensor and to compare different sensor configurations regarding the core radii of the optical fibers. The simulation results showed that the sensor configurations tested are highly sensitive to small angle variation (in the range of microradians) with nonlinearity less than or equal to 1%. The normalized sensitivity ranges from $(0.25\times V_{\max })$ to $(2.40\times V_{\max })\mathrm{mV}/\mathrm{\mu rad}$ (where $V_{\max }$ is the peak voltage of the static characteristic curve), and the linear range is from 194 to 1840 μrad. The unnormalized sensitivity for a reflective surface with reflectivity of 100% was measured as $7.7\mathrm{mV}/\mathrm{\mu rad}$. The simulations were compared with experimental results to validate the mathematical model and to define the most suitable configuration for ultrasonic detection. The sensor was tested on the characterization of a piezoelectric transducer and as part of a laser ultrasonics setup. The velocities of the longitudinal, shear, and surface waves were measured on aluminum samples as 6.43, 3.17, and $2.96\mathrm{mm}/\mathrm{\mu s}$, respectively, with an error smaller than 1.3%. The sensor, an alternative to piezoelectric or interferometric detectors, proved to be suitable for detection of ultrasonic waves and to perform time-of-flight measurements and nondestructive inspection.

An ultrasonic density-measurement cell is experimentally characterized as a function of temperature. The measurement of propagation velocity and density of several liquids is performed in the 15 degC-40 degC temperature range. Results are compared to the tabulated values in the case of distilled water, showing an accuracy of 0.07% for the propagation velocity. The cell was tested with distilled water, alcohol, and homogenized milk, and density values are compared to those obtained with a pycnometer, showing 0.2% accuracy in density measurement for stabilized temperature and 0.4% accuracy under thermal gradient conditions

Piezoelectric flextensional actuator (PFA) devices are increasingly being applied in precision mechanics, such as nanotechnology equipments, electronic microscopy instruments, cell manipulation systems, and microsurgery tools. These PFAs need to be characterized by measuring the produced nanodisplacements, and optical interferometry is well established as an accurate and precise technique for this application. In this paper, a new and efficient method for optical phase detection, here named generalized J ₁ /J ₃ method, is presented. As in the J ₁ /J ₃ conventional method, the new method is based on information contained in the photodetected signal spectrum when the drive voltage is sinusoidal and has a known frequency. The dynamic range of this method is from 0.26 to 100π rad (and higher), and only a limited number of frequencies in the magnitude spectrum of the photodetected signal are used, without the need to know the phase spectrum. The method has the advantages of being simple, passive homodyne, self-consistent, and immune to fading. Using the new method, two novel PFAs prototypes, designed using topology optimization method, are tested in terms of displacement linearity (relative to applied voltage) and frequency response.