scholarly journals Experimental Investigation of Inter-element Isolation in a Medical Array Transducer at Various Manufacturing Stages

2016 ◽  
Vol 39 (1) ◽  
pp. 62-74 ◽  
Author(s):  
Franco Marinozzi ◽  
Fabiano Bini ◽  
Andrea Grandoni
Keyword(s):  
Experimental Investigation ◽  
Lead Zirconate Titanate ◽  
Central Element ◽  
Laser Doppler Vibrometer ◽  
Cross Coupling ◽  
Lead Zirconate ◽  
Matching Layer ◽  
Array Transducer ◽  
Vibration Pattern ◽  
The One

This work presents the experimental investigation of vibration maps of a linear array transducer with 192 piezoelements by means of a laser Doppler vibrometer at various manufacturing finishing steps in air and in water. Over the years, many researchers have investigated cross-coupling in fabricated prototypes but not in arrays at various manufacturing stages. Only the central element of the array was driven at its working frequency of 5 MHz. The experimental results showed that the contributions of cross-coupling depend on the elements of the acoustic stack: Lead Zirconate Titanate (PZT), kerf, filler, matching layer, and lens. The oscillation amplitudes spanned from (6 ± 38%) nm to (110 ± 40%) nm when the energized element was tested in air and from (6 ± 57%) nm to (80 ± 67%) nm when measurements were obtained under water. The best inter-element isolation of −22 dB was measured in air after cutting the kerfs, whereas the poorest isolation was −2 dB under water with an acoustic lens (complete acoustic stack). The vibration pattern in water showed a higher standard deviation on the displacement measurements than the one obtained in air, due to the influence of acousto-optic interactions. The amount increased to 30% in water, as estimated by a comparison with the measurements in air. This work describes a valuable method for manufacturers to investigate the correspondence between the manufacturing process and the quantitative evaluations of the resulting effects.

Effects of Added Mass on Lead-Zirconate-Titanate (PZT) Thin-Film Microactuators in Aqueous Environments

2013 ◽  
Author(s):  
Chuan Luo ◽  
Chen-Wei Yang ◽  
G. Z. Cao ◽  
I. Y. Shen
Keyword(s):  
Thin Film ◽  
Lead Zirconate Titanate ◽  
Silicon Substrate ◽  
Laser Doppler Vibrometer ◽  
Lead Zirconate ◽  
Added Mass ◽  
Surrounding Water ◽  
Zirconate Titanate ◽  
Pzt Thin Film ◽  
Aqueous Environments

In this paper, we conduct experimental and theoretical studies of a lead-zirconate-titanate (PZT) thin-film microactuator probe submerged in water. The microactuator consists of a base silicon diaphragm, a layer of bottom electrode, a layer of lead-zirconate-titanate (PZT) thin film, and a layer of top electrode. The diaphragm is anchored on a silicon substrate by etching the silicon substrate from the back to form a cavity under the diaphragm. The diaphragm along with part of its anchor is then diced off from the silicon substrate to form a PZT probe and subsequently packaged with parylene. The probe tip has dimensions of 1 mm × 1 mm × 0.4 mm, while the diaphragm has dimensions of 800 μm × 800 μm × 2 μm. In the experimental study, frequency response functions of actuator displacement are measured via a laser Doppler vibrometer and a spectrum analyzer. The measurements show that the first natural frequency of the microactuator reduces from 80 kHz in air to 20 kHz when the microactuator is submerged in water. A literature search indicates that the surrounding water induces significant added mass to the microactuator. Estimation of the added mass based on theories in fluid mechanics successfully reconcile the predicted frequency to the vicinity of 20 kHz confirming the effects of added mass.

Development of Aluminum Nitride/Platinum Stack Structures for an Enhanced Piezoelectric Response

2006 ◽  
Vol 955 ◽  
Author(s):  
Adam Kabulski ◽  
John Harman ◽  
Parviz Famouri ◽  
Dimitris Korakakis
Keyword(s):  
Aluminum Nitride ◽  
Electric Fields ◽  
Lead Zirconate Titanate ◽  
Piezoelectric Coefficient ◽  
Piezoelectric Materials ◽  
Metal Layer ◽  
Laser Doppler Vibrometer ◽  
Lead Zirconate ◽  
Piezoelectric Response ◽  
High Electric Fields

ABSTRACTAluminum nitride (AlN) films are being investigated for piezoelectric and high temperature applications, but the piezoelectric response is still much lower than that of more common piezoelectric materials such as lead zirconate titanate or zinc oxide. A method of maximizing the piezoelectric response of aluminum nitride has been explored by depositing stack structures composed of aluminum nitride and platinum. These stack structures were created by depositing a thin, ∼50nm, metal layer in between thicker, ∼150-350nm, layers of the piezoelectric film. Platinum was chosen as the metal interlayer due to the tendency of AlN to become highly c-oriented when deposited on Pt. An electric field was applied across the structure and displacements were measured using a Laser Doppler Vibrometer. A maximum piezoelectric coefficient d33 was found to be over two times larger than the theoretical value for AlN (3.9pm/V). However, some of the stack structures were found to be conductive when measuring the displacement. I-V measurements as well as Fowler-Nordheim theory and plots were applied to investigate tunneling due to high electric fields in the structures.

An Experimental Investigation of the Cross-Coupling between Elements of an Acoustic Imaging Array Transducer

1982 ◽  
Vol 4 (1) ◽  
pp. 44-55 ◽  
Author(s):  
J. Fleming Dias
Keyword(s):  
Experimental Investigation ◽  
Surface Waves ◽  
Common Ground ◽  
Cross Coupling ◽  
Acoustic Mode ◽  
Acoustic Imaging ◽  
Range Resolution ◽  
Array Transducer ◽  
Coupling Mode ◽  
The Cross

In a phased array acoustic imaging transducer, the cross coupling between elements of the array can lead to a loss in range resolution, cause an increase in rolloff with angle of the sector scan, and increase the ringdown time. In this paper, we present results of an experimental investigation of an acoustic mode that couples the elements through the propagation of surface waves on the surface of the acoustic absorber. These results indicate that the strength of the mode is enhanced by the coherent reflections from adjacent neighbor elements which act as efficient reflectors of the surface waves. We also demonstrate a technique whereby reflections can be made to interact destructively to reduce the strength of that coupling mode. A further reduction can be obtained by stiffening the structure by bonding to the tops of the elements a thick brass foil and by using it as a common ground connection.

INFLUENCE OF THE INTER-ELEMENT COUPLING ON ULTRASOUND ARRAY RADIATION PATTERNS

2001 ◽  
Vol 09 (03) ◽  
pp. 773-788 ◽  
Author(s):  
P. GORI ◽  
A. IULA ◽  
M. PAPPALARDO ◽  
N. LAMBERTI ◽  
F. MONTERO DE ESPINOSA
Keyword(s):  
Radiation Pattern ◽  
Numerical Technique ◽  
Central Element ◽  
Cross Coupling ◽  
Filling Material ◽  
Radiation Patterns ◽  
Sommerfeld Integral ◽  
Array Transducer ◽  
Five Elements ◽  
The Cross

It is well known that the performances of the acoustic imaging arrays are degraded by the inter-element coupling sustained via the backing, the matching layers, and the kerf filler. The filling material inserted between the elements gives mechanical robustness to the array, but acts as a path of interaction, transmitting, between the elements, shear and lateral compressional forces. In this work, the effect on the array radiation pattern of the cross-coupling due to the filling material is investigated. A hybrid experimental–numerical technique is used. Two groups of five elements of a commercial array transducer were isolated and in one group the kerf filling material was removed. The cross-coupling waveforms, captured with a mechanical probe of small dimensions in contact with the emitting surfaces of the elements, were recorded for filled and unfilled groups of elements when: only the central element of the group was driven; all the elements were driven with the same pulse applied at the same time; all the elements were driven with the same pulse, but inverting the polarity alternately. This latter case refers to the worst coupling situation caused by the shear forces exerted between the elements. Fourier transforming the temporal signals, the cross-coupling transfer function of each element was computed and the radiation pattern was simulated by a numerical model based on the Rayleigh–Sommerfeld integral. Comparing the radiation patterns for filled and unfilled groups of elements, for the three cases mentioned above, a good estimation of the influence of the filling material is obtained.

Experimental Study of Cochlear Dynamics With an Intracochlear Acoustic Micro-Actuator

2019 ◽  
Author(s):  
Sergiy Taylakov ◽  
I. Y. Shen
Keyword(s):  
Lead Zirconate Titanate ◽  
Laser Doppler Vibrometer ◽  
Electrode Array ◽  
Petri Dish ◽  
Lead Zirconate ◽  
Squeeze Film ◽  
Test Rig ◽  
Micro Actuator ◽  
Squeeze Film Effect ◽  
Pzt Thin Film

Abstract An intracochlear lead-zirconate-titanate (PZT) micro-actuator can complement a cochlear implant electrode array to rehabilitate hearing loss patients with enhanced speech recognition. The presence of the intracochlear micro-actuator has significantly altered the cochlear dynamics, because the actuation now results from the micro-actuator instead of the stapes. To understand sound induction mechanisms by the micro-actuator, we design a test rig that mimics the box model of a human cochlea. The test rig consists of two connected fluid canals, one aluminum membrane sandwiched between the canals, and a PZT thin-film micro-actuator. Frequency response functions of the micro-actuator and the aluminum membrane are measured using a laser Doppler vibrometer and a spectrum analyzer. Measurements are taken when the micro-actuator is in air, in a petri dish surrounded by oil, and in the fluid canals inside the test rig. When the micro-actuator is moved from the petri dish (i.e., an open environment) to the inside of the fluid canals (i.e., a closed environment), the natural frequency and static gain of the micro-actuator both drop significantly indicating substantial increase in stiffness and inertia. A possible reason for the change, which remains to be confirmed, is the squeeze film effect from the fluid between the micro-actuator and the aluminum membrane.

Enhanced pyroelectric properties of PZT/PVDF-TrFE composites using calcined PZT ceramic powders

2013 ◽  
Vol 03 (01) ◽  
pp. 1350004 ◽  
Author(s):  
Chuan-Gui Wu ◽  
Guang-Qiang Cai ◽  
Wen-Bo Luo ◽  
Qiang-Xiang Peng ◽  
Xiang-Yu Sun ◽  
...  
Keyword(s):  
Lead Zirconate Titanate ◽  
Indium Tin Oxide ◽  
Figure Of Merit ◽  
Thick Films ◽  
Lead Zirconate ◽  
Pyroelectric Coefficient ◽  
Electric Properties ◽  
Glass Substrates ◽  
Different Temperatures ◽  
The One

The effects of calcined lead–zirconate–titanate (PZT) powders on the electric properties of PZT/polyvinylidene-trifluorethylene copolymer (PVDF-TrFE) composites thick films were studied in this paper. Firstly, the PZT powders synthesized by hydrothermal method were calcined at different temperatures ranging from 300°C to 900°C, and then the PZT/PVDF-TrFE composites films were produced by casting PZT/PVDF-TrFE suspension onto the indium-tin-oxide (ITO)-coated glass substrates. Electric properties, including dielectric and pyroelectric performances of thick films consisting of PZT powders calcined at different temperatures were tested. The highest pyroelectric coefficient obtained in the sample using 700°C calcined PZT powders was 96 μCm-2K-1, which was 20% higher than the composites made of uncalcined powders. Additionally, the highest detectivity figure-of-merit (FOM) (F D ) of the composite was 1.36 × 10-5Pa-1/2, which increased about 13.5% compared to the one using uncalcined powders.

scholarly journals Effects of Added Mass on Lead-Zirconate-Titanate Thin-Film Microactuators in Aqueous Environments

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Chuan Luo ◽  
W. C. Tai ◽  
Cheng-Wei Yang ◽  
G. Z. Cao ◽  
I. Y. Shen
Keyword(s):  
Thin Film ◽  
Finite Element ◽  
Natural Frequency ◽  
Lead Zirconate Titanate ◽  
Laser Doppler Vibrometer ◽  
Lead Zirconate ◽  
Added Mass ◽  
Surrounding Water ◽  
Zirconate Titanate ◽  
Pzt Thin Film

In this paper, we conduct experimental, theoretical, and numerical studies of a lead-zirconate-titanate (PZT) thin-film microactuator probe submerged in water. The major component of the actuator is a PZT diaphragm anchored on four silicon sidewalls. There is also silicon residue at the juncture of the diaphragm and the sidewalls due to imperfect etching processes. In the experimental study, frequency response functions of actuator displacement are measured via a laser Doppler vibrometer and a spectrum analyzer. The measurements show that the first natural frequency of the microactuator reduces from 80 kHz in air to 20 kHz when the microactuator is submerged in water. A viable explanation is that the surrounding water induces significant added mass to the microactuator. Estimation of the added mass based on theories in fluid mechanics successfully reconciles the predicted frequency to the vicinity of 20 kHz confirming the effects of added mass. Finite element models are also created to study how the silicon sidewalls and residue affect the added mass. Simulations show that presence of the sidewalls or residue would modify the fluid flow thus altering the added mass and natural frequency. In general, the finite element predictions agree well with the experimental measurements within 10% difference.

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