S. Simon Wong

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Crosstalk is the coupling of energy between the elements of an ultrasonic transducer array. This coupling degrades the performance of transducers in applications such as medical imaging and therapeutics. In this paper, we present an experimental demonstration of guided interface waves in capacitive micromachined ultrasonic transducers (CMUTs). We compare(More)
In the last decade, high intensity focused ultrasound (HIFU) has gained popularity as a minimally invasive and noninvasive therapeutic tool for treatment of cancers, arrhythmias, and other medical conditions. HIFU therapy is often guided by magnetic resonance imaging (MM), which provides anatomical images for therapeutic device placement, temperature maps(More)
An RF-path 60-GHz band 4-element array using proposed phase-oversampling vector modulation is implemented in 65-nm CMOS. Digitally controlled semi-lookup table method is proposed to compensate for non-idealities in circuits, antenna array, and interfaces. Accurate and high resolution control on the gain and phase is demonstrated. The receiver features an NF(More)
This paper analyzes element-to-element and cellto-cell cross-coupling in capacitive micromachined ultrasonic transducers (cMUTs) using an interferometer. In a 1-D linear cMUT array immersed in oil, a single element was excited, and membrane displacements were measured at different positions along the array with an interferometer. Electrical measurements of(More)
Increasing fill factor is one design approach used to increase average output displacement, output pressure, and sensitivity of capacitive micromachined ultrasonic transducers (CMUTs). For rectangular cells, the cell-to-cell spacing and the aspect ratio determine the fill factor. In this paper, we explore the effects of these parameters on performance, in(More)
In the past ten years, high intensity focused ultrasound (HIFU) has become popular for minimally invasive and non-invasive therapies. Traditionally piezoelectric transducers have been used for HIFU applications, but capacitive micro- machined ultrasonic transducers (CMUTs) have been shown to have advantages, including ease of fabrication and efficient(More)
High intensity focused ultrasound (HIFU) guided by magnetic resonance imaging (MRI) is a noninvasive treatment that can potentially reduce morbidity, lower costs, and widen accessibility for patients with upper abdominal cancers. Traditionally, piezoelectric transducers are used for HIFU, but recent developments in capacitive micromachined ultrasonic(More)
Atrial fibrillation (AF) affects 1% of the population and results in a cost of $2.8 billion from hospitalizations alone. Treatments that electrically isolate portions of the atria are clinically effective in curing AF. However, such minimally invasive catheter treatments face difficulties in mechanically positioning the catheter tip and visualizing the(More)
The accurate prediction of the static operation point of capacitive micromachined ultrasonic transducer (CMUT) membranes is essential for dynamic performance modeling, device design, and device fabrication. We evaluate whether fabrication-related stress effects in CMUT cells cause significant deviations observed between membrane deflection measurements and(More)
Ultra-wideband (UWB) impulse radio systems based on non-coherent on-off keying (OOK) energy detection are relatively simpler to implement than their coherent counterparts, because the strict synchronization requirements are relaxed. However, the design challenge is to set a hard decision threshold value after energy detection because the detected energy may(More)