January 2024
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17 Reads
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January 2024
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17 Reads
August 2022
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81 Reads
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3 Citations
Microscopy and Microanalysis
This work reports high-frequency ultrasonic imaging to visualize and study microscopic pests such as nematodes. This imaging modality using ultrasound instead of light enables visualizing nematodes even under the soil. This GHz technology uses a compact 128 x 128-pixel array of transducers that allow imaging at a sampling rate of up to 12 fps. The images can be viewed in real-time and further processed to measure the worms’ spatial dimensions such as length, width, as well as velocity. Here, we show that the ultrasonic imaging approach can be a powerful tool to visualize and detect microscopic pests such as nematodes and study their behavior in their natural habitat.
July 2022
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39 Reads
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3 Citations
IEEE Electron Device Letters
In this work, we employed our newly developed optical imaging method to probe detailed acoustodynamic physics in gigahertz unreleased ultrasonic transducers based on an AlN-on-silicon system, revealing mode superposition, anisotropic transduction, and dynamic mode evolution. Superpositioned upon the dominant breathing mode along the vertical direction of the AlN layer, multiple resonant lateral modes are identified, and they are shown to evolve into a surface mode beyond the piezoelectric transduction envelope, with strong anisotropic transduction brought by the shear motion of silicon. This acoustodynamic property is important for verifying and further improving design theories of broadband piezoelectric transducers and thin film piezoelectric-on-substrate systems in general.
February 2022
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266 Reads
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23 Citations
Dynamic measurement of femtometer-displacement vibrations in mechanical resonators at microwave frequencies is critical for a number of emerging high-impact technologies including 5G wireless communications and quantum state generation, storage, and transfer. However, the resolution of continuous-wave laser interferometry, the method most commonly used for imaging vibration wavefields, has been limited to vibration amplitudes just below a picometer at several gigahertz. This is insufficient for these technologies since vibration amplitudes precipitously decrease for increasing frequency. Here we present a stroboscopic optical sampling approach for the transduction of coherent super high frequency vibrations. Phase-sensitive absolute displacement detection with a noise floor of 55 fm/√Hz for frequencies up to 12 GHz is demonstrated, achieving higher bandwidth and significantly lower noise floor simultaneously compared to previous work. An acoustic microresonator with resonances above 10 GHz and displacements smaller than 70 fm is measured using the presented method to reveal complex mode superposition, dispersion, and anisotropic propagation.
October 2018
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45 Reads
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7 Citations
January 2018
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32 Reads
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5 Citations
September 2017
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18 Reads
September 2017
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19 Reads
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1 Citation
September 2017
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27 Reads
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4 Citations
September 2017
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18 Reads
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3 Citations
... However, the spatial resolution (0.5 -2mm) provided by this frequency range is insufficient for smaller organisms to capture their fine structural details. On the other hand, GHz frequencies offer significantly higher resolution of ∼0.5 m to 50 , which have been previously used to study cells [9], [10], soil nematodes [11], thin chitosan films [12], and metamaterial lenses [13]. Therefore, GHz Ultrasonic Imaging has the potential to resolve mechanical properties of C. elegans at a higher resolution. ...
August 2022
Microscopy and Microanalysis
... Most high piezoelectric response and large ferroelectric polarization in experiments occurred in tetragonal phase or mixed phases 13 . Here, we focus on the P4mm (space group) tetragonal phase (other tetragonal perovskite phases are not ferroelectric or piezoelectric) and a longstanding problem, piezoelectric anisotropy, which is fundamentally important for modern engineering applications like ultrasonic transducers 14 and robotic metamaterials 15 . Highly anisotropic materials can provide minimal noise from lateral vibrations, greatly reducing manufacturing costs by skipping the precise control of the size of pezoelectric vibrator, eg., the length/thickness ratio, to produce the clean thickness resonance mode. ...
July 2022
IEEE Electron Device Letters
... 28 Here, we demonstrate a method for optically measuring and manipulating the mechanical resonator of a YIG microsphere using optical heterodyne detection. [29][30][31][32][33] This technique allows for highly accurate retrieval of vibration information from the YIG sphere, including center frequency, amplitude, and linewidth. Our optical measurements have good agreement with microwave measurements, while also providing spatial resolution by mapping the distribution of mechanical vibrations along the equator of the YIG sphere. ...
February 2022
... 10 The phase-shift method was used by Abdelmejeed et al. to measure the temperature of a silicon wafer using a voltage control oscillator. 11 The thickness of the sample investigated (0.65 mm) is small when compared to many machining applications. The attenuation of the signal in a larger workpiece means that this signal source would not be appropriate. ...
January 2018
... CMOS-integrated GHz transducers can create compact devices, enabling low cost and miniature implementation. [64][65][66][67][68] Furthermore, this technique is label-free, and does not require surface functionalization to capture the analyte of interest as it simply relies on the acoustic impedance measurement. Representative of this technology, this paper reports measurements with GHz ultrasonic bulk waves generated by a 70 mm square aluminum nitride, or AlN thin-film transducers fabricated on a silicon wafer. ...
January 2017
... The center frequency for GHz transducers is set by the AlN and top dielectric thin film layer thicknesses, but several key functions are lithographically definable such as adjusting acoustic beam width through transducer sizing, adjusting echo amplitudes through transducer spacing, and adjusting diffraction characteristics through layout [14]. This flexibility allows GHz transducers to be used in a variety of configurations such as for GHz ultrasonic imaging [15], ultrasonic communication channels [16], temperature sensing [17], and clock oscillators [18]. By allowing users some choices in AlN and top dielectric layer thicknesses, more control over device operating frequencies can be realized. ...
September 2017
... Also, impediography technique has been experimented by exploiting aluminum nitride (AlN) piezoelectric thin films working at frequencies higher than 1 GHz [109]. Images of fingerprint rubber phantoms were collected by swiping the phantom itself across a 64 element linear array [110,111]. The capability of such transducer of discriminating among several loads has been demonstrated as well. ...
September 2017