A novel electromechanical foam (EFOAM) material capable of acting as an electromechanical transducer with integrated functions as a sensoractuator is investigated by manufacturing some samples of the foam and performing some tests, based on the piezo-electric effect in electro-active polymers. The resulting charge, when different known weights are applied to the sample were observed and recorded with a charge amplifier while the actuator sensitivity was also estimated using the micro-scanning laser Doppler vibrometer. EFOAM is manufactured from expancel microspheres and heated by placing the microspheres in glass slides heated up to temperatures of 135 0 C for expansion. Different samples were manufactured and charged using the corona discharge method operating under an electric field of between 11kV/cm to 15kV/cm. EFOAM displayed an electro-mechanical sensitivity of 1nm/V when characterized, and is observed that the piezoelectric nature of EFOAM exists as a characteristic of each cell within the material sample. This novel material offers much promise in the area of production of miniature electromechanical devices which maybe well applied in electroacoustic applications.

Wi n d mill C e ntr e f or Ultr as o ni c E n gi n e eri n g, El e ctr o ni c & El e ctri c al E n gi n e eri n g D e pt., Bi o a c o usti cs Gr o u p, U ni v ersit y of Str at h cl y d e Gl as g o w, S c otl a n d, U nit e d Ki n g d o m Ol u w as e u n. o m o ni yi @str at h. a c. u k

Sugar casting is a simple and cost-effective direct method of generating polymer foams. By incorporating grains directly into mixtures of polymer and piezoelectric nanoparticles it is possible to create highly compliant materials with excellent piezoelectric properties. In this work, we use the sugar casting method in combination with spin coating to prepare a highly sensitive and flexible 0-3 piezoelectric polymer thin film membranes with a layer thickness of 20 to 190 µm. Porosities and elasticity are tuned by simply adjusting the sugar/polymer mass ratio. The expected outcome of this research was improvements to the piezoelectric voltage, the g 33 measure, due to the increased compliance of the material, however iezoelectric composite membranes with high concentrations of PMN-PT also demonstrated gains in piezoelectric coupling, the d 33 measure, when cast with high volume fractions of sugar. A remarkably high d 33 coefficient of 69 pm/V was measured using the laser vibrometer technique. These innovative materials were developed as broadband ultrasonic sensors for partial discharge detection in undersea cables, however they have potential uses in energy scavenging platforms, biosensors, and acoustic actuators, among others.

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The development of 3D-printed sensors and actuators from piezocomposite materials has increased in recent years due to the ease of production, low-cost and improved functionality additive manufacturing provides. The piezocomposite material developed in this work has the potential to be used as a functional material in stereolithographic additive manufacturing by combining the optical, viscoelastic properties of NOA 65 and the piezoelectric properties of Barium Titanate. The new (0–3) piezocomposite material consists of Norland Optical Adhesive 65 (NOA 65) as the polymer matrix and Barium Titanate (BaTiO3) with particles sizes (100 nm, 200 nm and 500 nm) as the dielectric filler. We synthesized thin film samples of the (0–3) piezocomposite with 60% w/w BaTiO3 using solution mixing and spin coating method to produce samples with layer thickness of 100 µm. Fourier-transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) techniques were used to analyze the microstructure of the piezocomposite to determine the effect of different particles sizes of BaTiO3 on the structural and mechanical properties of the composite. The longitudinal piezoelectric coefficient d33 was also measured using the laser vibrometer technique. Both single point scans and full surface scans were carried out to obtain the average piezoelectric coefficient d33 of the composite material. The results of the SEM confirmed the (0–3) structure of the piezocomposite material with isolated BaTiO3 nanoparticles. It further showed the uniform distribution of the BaTiO3 nanoparticles across each of the samples. FTIR analysis showed that the filler nanoparticles had no effect on the native structure of the polymer matrix. The longitudinal piezoelectric coefficient d33 of the piezocomposite material was observed to increase with increasing BaTiO3 particle sizes, while the indentation modulus of the composite investigated using the method of Oliver and Pharr was observed to decrease with an increase in particle size. Results from the single point scans showed the composite with BaTiO3 particle size 100 nm, 200 nm and 500 nm having an average d33 of 2.1 pm/V, 3.0 pm/V and 3.9 pm/V while the average d33 obtained from the full surface scan of 1430 scan points showed 1.4 pm/V, 6.1 pm/V, 7.2 pm/V.

In this study, we have developed and characterized two different (0-3) piezoelectric composite materials with potential to be used in sensing applications. The composite materials were made using Polydimethylsiloxane (PDMS) as the polymer matrix with Barium Titanate (BaTiO3), and Lead Zirconate Titanate (PZT51) as the dielectric fillers. Thin film samples of the (0-3) piezocomposites were prepared using a solution mixing and spin coating method to produce composites with (0-3) connectivity pattern and layer thickness of 100 µm. The microstructure of the piezocomposites were analyzed using a scanning electron microscope to determine the connectivity structure and homogeneity of the piezocomposites. The mechanical properties of the composites were determined using the method of Oliver and Pharr. FTIR analysis was used to determine the effects of the fillers on the structure of the piezocomposite. The average piezoelectric d33 coefficient of the piezocomposites were also measured using the laser vibrometer technique and determined to be 30 pm/V for the piezocomposite consisting of Barium Titanate (BaTiO3) and 32 pm/V for the piezocomposite consisting of Lead Zirconate Titanate (PZT51).

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