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It is critical to use a proper spatial sampling, otherwise images suffer from grating lobes. However, the cost of a medical ultrasound scanner is strongly related to the channel count of the receive electronics. This has led to channel reduction using multiplexing or in-probe pre-beamforming methods at the cost of image quality or frame rate. An alternative is to reduce the receive channel count and...
The constantly rising demand for higher data rates is addressed by advanced communication standards like carrier aggregation (CA) in combination with LTE. The increased complexity of the RF frontend has put tremendous pressure on improving linear performance of BAW filters over the last years. On top of that a large number of intermodulation (IMD) specification have been added to safeguard all CA...
Partial substitution of Al by Sc in AlN wurtzite films leads to a strong enhancement of the piezoelectric properties as long as the wurtzite phase is maintained. This is very promising for improving piezoelectric MEMS devices and enlarging their application range. Nucleation of (0001)-AlScN works particularly well on Pt (111) thin films. However, in some applications, the growth on insulating substrates...
Energy harvesting from surrounding electromagnetic wave can satisfy the increasing demand of trillions of wireless sensors for IoT. RF energy harvesting is generally achieved by RF-DC conversion using a rectifying antenna (called rectenna). For weak RF signal, however, RF-DC conversion efficiency significantly decreases because weak RF signal cannot activate the diode in the rectenna. Therefore, in...
Fast acquisition sequences enable >200Hz 2D cardiac B-mode imaging with little compromise in image quality. Fast imaging minimizes frame to frame decorrelation, enabling radiofrequency (RF)-based tracking for enhanced signal-to-noise ratio (SNR) in motion and deformation imaging. Our objective was to compare the performance and clinical usefulness of Fast RF-based Tracking (FRFT) to the established...
Bulk thermal ablation, including radiofrequency ablation (RFA) as well as microwave and ultrasound (US) ablation, is an important approach to tumor treatment. To avoid incomplete treatments and cancer recurrence while reducing morbidity, a real-time monitoring and control approach, capable of providing consistent thermal ablation in minimum time, is needed. Echo decorrelation imaging has been successfully...
Design of side edges is one of the most important tasks for realization of high performance RF SAW/BAW devices. For the purpose, the authors proposed an FEM based technique where the specified mode is injected to the border under concern through a damping mechanism, and scattering coefficients are estimated from calculated BAW field [1]. Even though this technique is effective, its setup is too complicated...
The authors developed phase-sensitive and fast mechanical scanning laser probe system as a diagnosis tool for RF SAW/BAW devices[1]. Captured 2D image of wave field brings valuable information such as energy leakage and standing wave pattern with a help of a wavenumber domain analysis[2] for a specified driving frequency. Although the system is frequently used by external researchers and engineers...
An effective imaging modality to delineate the ablated region after microwave ablation (MWA) therapy is crucial to yield promising treatment outcomes. Ultrasound B mode imaging is widely used to guide the ablation needle. However, the image quality suffers from relatively low imaging contrast due to the similar echogenicity between the ablated and surrounding liver tissue. In this study, we applied...
RF filtering technologies based on piezoelectric MEMS resonators have been successfully developed and commercialized in the past decade thanks to their size and outstanding performance. The challenge to enhance filter's performance in terms of lower insertion losses and wider bandwidth still makes for an active research topic, especially spurring the interest for new classes of materials such as doped-AlN...
Ultrafast imaging based on plane wave (PW) / diverging wave (DW) is an active area of research in ultrasound acquisitions because of its capacity of reaching high frame rate. Beamforming of received echoes in Fourier domain provides comparable image quality but lower computational complexity with respect to the conventional DAS approach [Zhang et al., UFFC, 2016]. However, the current state-of-the-art...
The Reference Phantom Method can be used to quantify acoustic properties of tissue by compensating for system effects using the average power spectrum from a well-characterized homogeneous medium. Widespread clinical application of the Reference Phantom Method is hindered by the need to scan the reference phantom using the same transducer, system, and system settings as used for scanning the tissue...
Multi-planar reformatting (MPR) in 3-D ultrasound imaging provides the viewer with planar cross-sectional images extracted from the 3-D data. To produce the MPR imaging from the acquired 3-D volume data, the 3-D scan conversion (SC), which transforms the acquired data in the 3-D polar coordinate system to the 3-D Cartesian coordinate system, is performed for display. Direct 3-D SC and separable 3-D...
Obtaining ultrafast images using steered plane wave (PW) imaging remains a challenge due to the trade-off between image quality and frame rate. PW imaging indeed relies on compounding in order to preserve a good image quality, usually using multiple successive emissions, which in turn yields a decrease of the frame rate. As opposed to this classical approach, we propose a new strategy to reduce the...
Multi-line transmission (MLT) is a recently developed method for high frame rate cardiac ultrasound imaging. However, a potential pitfall of this method is the presence of artifacts due to cross-talk between the MLT beams. Low complexity adaptive beamforming (LCA) is a high resolution adaptive beamforming method that chooses a weighting function out of a predefined set of apodization functions assembled...
Ultrafast ultrasound has contributed to a renewed interested in vector Doppler. Sampling RF signals at a rate 4 times the carrier frequency is the standard procedure since this rule complies with the Nyquist sampling theorem, regardless of the transducer bandwidth. RF acquisition with a high-performance multi-channel system generates massive datasets, especially in 3-D ultrafast ultrasound. The objective...
Mobile filters are required to process increasing RF power levels, driven by the need for higher data-rates and improved cell-edge coverage. This results in more demanding filter specifications for loss, rejection, isolation, linearity and reliability, while, at the same time, handset OEMs require smaller filter footprints.
Amyotrophic Lateral Sclerosis (ALS) is a fatal motor neuron progressive disorder that leads to muscle deterioration and paralysis. There is a crucial need to identify new therapeutic approaches and validate methods to assess their efficacy. The objective was to develop a high frame rate vectorised approach to visualize and analyze the 2D transient contractile wave propagation of muscle tissue with...
Quasi-static elastography is a widely applied ultrasound method in which RF data acquired in tissue at different states of deformation are correlated to estimate displacements and strain (displacement gradient). A recent development is the introduction of ultrafast plane-wave imaging where element data are beam-formed after collection to reconstruct the image lines. Several beam-forming strategies...
High frequency bands such as LTE band 42 and band 43 require resonators and filters that can operate at frequencies higher than 3 GHz. However, existing lithium niobate fundamental symmetric (S0) lamb mode resonators and surface acoustic wave (SAW) resonators have operating frequency limitations (<2 GHz) due to their low phase velocities. High frequency AlN film bulk acoustic resonators (FBARs)...
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