Focusing of ferroelectret air-coupled ultrasound transducers

Gaal, Mate; Bartusch, Jürgen; Dohse, Elmar; Schadow, Florian; Köppe, Enrico

doi:10.1063/1.4940533

Cited by 16 publications

(8 citation statements)

References 11 publications

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“…Gaal et al [151] developed an ultra-low noise pre-amplifier for air-coupled ultrasonic receiver with an output impedance of 1 to 10 MΩ an extremely high input impedance of 100 MΩ // 10 pF (See Figure 17). Noting the high voltage levels of amplifier close to the breakdown of the exciter, Mariani et al [13] used PSpice software to design L type networks based EIMN for the receiver side.…”

Section: Nondestructive Evaluation Of Composite and Sandwich Structuresmentioning

confidence: 99%

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A Review of Electric Impedance Matching Techniques for Piezoelectric Sensors, Actuators and Transducers

Rathod

2019

Electronics

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Any electric transmission lines involving the transfer of power or electric signal requires the matching of electric parameters with the driver, source, cable, or the receiver electronics. Proceeding with the design of electric impedance matching circuit for piezoelectric sensors, actuators, and transducers require careful consideration of the frequencies of operation, transmitter or receiver impedance, power supply or driver impedance and the impedance of the receiver electronics. This paper reviews the techniques available for matching the electric impedance of piezoelectric sensors, actuators, and transducers with their accessories like amplifiers, cables, power supply, receiver electronics and power storage. The techniques related to the design of power supply, preamplifier, cable, matching circuits for electric impedance matching with sensors, actuators, and transducers have been presented. The paper begins with the common tools, models, and material properties used for the design of electric impedance matching. Common analytical and numerical methods used to develop electric impedance matching networks have been reviewed. The role and importance of electrical impedance matching on the overall performance of the transducer system have been emphasized throughout. The paper reviews the common methods and new methods reported for electrical impedance matching for specific applications. The paper concludes with special applications and future perspectives considering the recent advancements in materials and electronics.

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Section: Nondestructive Evaluation Of Composite and Sandwich Structuresmentioning

confidence: 99%

“…Focusing transducer based on cellular polypropylene with an electric matching unit shown in the background for air-coupled ultrasonic testing. Reproduced with permission from Reference[151], Copyright AIP, 2016.…”

mentioning

confidence: 99%

A Review of Electric Impedance Matching Techniques for Piezoelectric Sensors, Actuators and Transducers

Rathod

2019

Electronics

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“…Both transducers had a bandwidth of 20% (-6 dB) and the diameter of their soundfield in focus 2.5 mm (-6 dB). 25 The corresponding C-scan results are shown in Figure 2(f).…”

Section: Air Coupled Ultrasound: Piezoelectric Transducers and Opticamentioning

confidence: 99%

Qualitative comparison of non-destructive methods for inspection of carbon fiber-reinforced polymer laminates

Rus

Gustschin

Mooshofer

et al. 2020

Journal of Composite Materials

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In the rapidly expanding composite industry, novel inspection methods have been developed in recent years. Particularly promising for air-coupled testing are cellular polypropylene transducers which offer better impedance matching to air than piezoelectric transducers. Furthermore, broadband transmitters (laser-induced ultrasound and thermoacoustic emitters) and receivers (optical microphones) have opened a completely new chapter for advanced contact-free ultrasound inspection. X-ray dark-field radiography offers a different approach to detect porosity and microcracks, employing small angle X-ray scattering. These innovative ultrasonic and radiographic alternatives were evaluated in comparison with well-established inspection techniques. We applied thirteen different non-destructive methods to inspect the same specimen (a carbon fiber-reinforced polymer laminate with induced impact damage): air-coupled ultrasound testing (using piezoelectric transducers, broadband optical microphones, cellular polypropylene transducers, and a thermoacoustic emitter), laser-induced ultrasound testing, ultrasonic immersion testing, phased array ultrasonic testing, optically excited lock-in thermography, and X-ray radiography (projectional absorption and dark-field, tomosynthesis, and micro-computed tomography). The inspection methods were qualitatively characterized by comparing the scan results. The conclusions are advantageous for a decision on the optimal method for certain testing constraints.

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“…Ferroelectrets have been used for many different applications including microphones [ 18 ], energy harvesting [ 19 , 20 , 21 ], wearable devices [ 22 ] and flexible and printable sensors (FLEPS) [ 23 ], flexible touch pads and tactile sensors [ 24 ], and air-coupled ultrasonic transducers [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ]. In the latter case, the main advantage is the extremely low acoustic impedance of these materials that facilitates the coupling to the air; they are normally operated using the thickness resonances of the films.…”

Section: Introductionmentioning

confidence: 99%

Modification of Mechanical and Electromechanical Resonances of Cellular Ferroelectret Films Depending on the External Load

Aguilar

Álvarez-Arenas

2021

Polymers

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Ferroelectret films are cellular polymers with electrically charged pores that exhibit piezoelectric response. Among other applications, ferroelectret films have been widely used as active elements in air-coupled ultrasonic transducers. More recently, they have also been tested in water immersion. They show a promising wide frequency band response, but a poor sensitivity produced by the disappearance of the electromechanical resonances. This paper studies in detail the modification of FE films response when put into water immersion, both the mechanical and the electromechanical responses (the latter in transmission and reception modes). The lack of electromechanical thickness resonances when the films are put into water is explained as the result of the different profile of the modification of the polarization vector along the film thickness imposed by the large mechanical load produced by the water. This different electromechanical response can also be the reason for the subtle modification of the mechanical thickness resonances that is also observed and analyzed.

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Focusing of ferroelectret air-coupled ultrasound transducers

Cited by 16 publications

References 11 publications

A Review of Electric Impedance Matching Techniques for Piezoelectric Sensors, Actuators and Transducers

A Review of Electric Impedance Matching Techniques for Piezoelectric Sensors, Actuators and Transducers

Qualitative comparison of non-destructive methods for inspection of carbon fiber-reinforced polymer laminates

Modification of Mechanical and Electromechanical Resonances of Cellular Ferroelectret Films Depending on the External Load

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