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Intracardiac echocardiography (ICE) is routinely used in many interventional procedures in cardiology. In these procedures ICE catheter is positioned with fluoroscopy guidance, which can be harmful due to ionizing X-ray radiation exposure. Positioning the ICE catheter using an interventional magnetic resonance imaging (MRI) system would enable procedures that are free of ionizing radiation, and complement...
This paper presents an catheter prototype developed for testing feasibility of intracardiac echography (ICE) in a magnetic resonance imaging (MRI) system. The presented catheter includes a capacitive micromachined ultrasonic transducer (CMUT) array at its tip, a 1m long catheter body with μ-coax cable based connections to a handle. The handle contains ultrasound pulser circuitry to generate the excitation...
CMUT efficiency depends on a high electric field over a thin vacuum gap and a dielectric isolation layer. Ideally this high electric field should only exist over the vibrating membrane of the CMUT, but electrical connections between the membranes usually pass over thin dielectric isolation layers (Fig. 1). The resulting high fields on the isolation layer cause charging, dielectric breakdown and reduces...
Capacitive micromachined ultrasonic transducers (CMUTs) are prone to having low transmit sensitivity. According to large signal CMUT models, this shortcoming can be overcome with higher pulse voltages and optimized bipolar pulse drives [1]. Therefore, a supply-inverted bipolar pulser and a Tx/Rx switch are proposed to drive CMUTs in medical ultrasound imaging applications. These circuits are particularly...
3-D imaging ICE catheters with large element counts present design challenges in achieving simultaneous data readout from all elements while significantly reducing cable count for a small catheter diameter. Current approaches such as microbeamformer techniques tend to rely on area and power hungry circuits, making them undesirable for ICE catheters. In this paper, a system which uses are an efficient...
SiO2 nanostructures have been fabricated by sequential etching/passivation treatment of an amorphous SiO2 layer, using mixture of SF6, H2 and O2 gases. Photoluminescence measurements depicts that nano-textured SiO2 films have emission spectra between 530 and 580 nm depending on the details of the sample treatment. The effects of sequence numbers, post-RIE-process hydrogenation treatment, and annealing...
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