Aspects of this disclosure relate to driving a capacitive micromachined ultrasonic transducer (CMUT) with a pulse train of unipolar pulses. The CMUT may be electrically excited with a pulse train of unipolar pulses such that the CMUT operates in a continuous wave mode. In some embodiments, the CMUT may have a contoured electrode.

Aspects of this disclosure relate to driving a capacitive micromachined ultrasonic transducer (CMUT) with a pulse train of unipolar pulses. The CMUT may be electrically excited with a pulse train of unipolar pulses such that the CMUT operates in a continuous wave mode. In some embodiments, the CMUT may have a contoured electrode.

A method and system for inspecting a rail by guided waves, the rail being instrumented by sensors. The method comprises the steps of receiving elastic wave measurements from one or more sensors, as a train passes, releasing energy as guided waves into the rail; and of determining a function representative of the impulse response of the rail and the sensors. Developments describe how to determine the existence, position and characterisation of a defect in the rail (e.g. fracture, incipient fracture, etc.), the use of inter-correlation analyses, correlation of the coda of correlations, Passive Inverse Filter, imaging techniques. Other aspects are described for exploring rail defects: sensor position and movement, acquisition time, sampling frequency, frequency filters, amplifications, techniques for learning during successive train passes, signal injection by transducers. Software aspects are described.

Systems and methods for improving spectral-shift methods for calculating acoustic attenuation coefficients are disclosed. Systems, methods, and apparatuses for transmitting ultrasound pulse sequences for improved signal-to-noise outside the main passband of ultrasound transducers are disclosed. Systems, methods, and apparatuses for using the echoes from the transmitted pulse sequences to calculate the attenuation coefficient are disclosed.

A micromachined ultrasonic transducer (MUT). The MUT includes: a substrate; a membrane suspending from the substrate; a bottom electrode disposed on the membrane; a piezoelectric layer disposed on the bottom electrode and an asymmetric top electrode is disposed on the piezoelectric layer. The areal density distribution of the asymmetric electrode along an axis has a plurality of local maxima, wherein locations of the plurality of local maxima coincide with locations where a plurality of anti-nodal points at a vibrational resonance frequency is located.

The present disclosure is generally directed to an ultrasonic transducer interface system for use within portable 2-D ultrasonic imagers and includes an on-chip adaptive beamformer and Charge-Redistribution TX (CR-TX) to provide a drive strength of up to 500 pF/channel at 5 MHz (or 10 nF at 250 kHz) while reducing the TX drive power by at least 30% compared to other ultrasonic transducer TX drivers. The ultrasonic transducer interface system can be implemented in a single chip via, for example, a complementary metal oxide semiconductor (CMOS) process.

An ultrasound probe includes a first assembly having a first case, a second assembly coupled with the first assembly, having a second case, and configured to be rotatable between a first position of being unfolded with respect to the first assembly and a second position of being folded on the first assembly, a first acoustic module disposed in the inside of the first case, a second acoustic module disposed in the inside of the second case, and a first space reducing portion disposed in at least one of a portion of the first case toward the second assembly and a portion of the second case toward the first assembly, and configured to reduce a space between the first acoustic module and the second acoustic module when the second assembly is at the first position.

Aspects of this disclosure relate to driving a capacitive micromachined ultrasonic transducer (CMUT) with a pulse train of unipolar pulses. The CMUT may be electrically excited with a pulse train of unipolar pulses such that the CMUT operates in a continuous wave mode. In some embodiments, the CMUT may have a contoured electrode.

An array of CMUT cells has a DC bias voltage (VB) coupled to the membrane and floor electrodes of the cells to bias the electrode to a desired collapsed or partially collapsed state. The low voltage or ground terminal of the DC bias supply is coupled to the patient-facing membrane electrodes and the high voltage is applied to the floor electrodes. An ASIC for controlling the CMUT array is located in the probe with the array. The ASIC electronics are electrically floating relative to ground potential of the ultrasound system to which the CMUT probe is connected. Control and signal lines are coupled to the CMUT probe by level shifters which translate signals to the floating potential of the ASIC and provide DC isolation between the CMUT probe and the ultrasound system.

A system for measuring a gas concentration, the system including: a first oscillator including a first surface for placement in a sampling location, wherein the first oscillator oscillates at a frequency greater than 20,000 Hz but less than 300,000,000 Hz; a first counter to accumulate a count of oscillations of the first oscillator; and a comparator to calculate a difference between the accumulated counts of the first oscillator and a reference, wherein the difference calculated by the comparator is sampled at a frequency of less than 100 Hz.