Micromachined ultrasonic transducers integrated with complementary metal oxide semiconductor (CMOS) substrates are described, as well as methods of fabricating such devices. Fabrication may involve two separate wafer bonding steps. Wafer bonding may be used to fabricate sealed cavities in a substrate. Wafer bonding may also be used to bond the substrate to another substrate, such as a CMOS wafer. At least the second wafer bonding may be performed at a low temperature.

A structure that prevents a substrate from being warped is provided on a region or a location other than a membrane that determines the characteristics of a CMUT. In a CMUT in a structure in which a first conductive layer and a second conductive layer are provided sandwiching a cavity on a substrate, for example, as a warpage prevention structure, a warpage prevention layer that prevents the substrate from being warped is provided between the substrate and the first conductive film. When the insulating film disposed between the cavity and the first conductive film and the insulating film disposed between the cavity and the second conductive film are silicon oxide films, the warpage prevention layer includes a silicon nitride film.

The present disclosure is generally directed to a method for driving an ultrasonic transducer. The method includes coupling a driving electrode and a ground electrode of the ultrasonic transducer to a power supply and a ground, respectively, during a first time period based on a received drive signal. The method further includes decoupling the driving electrode and the ground electrode of the ultrasonic transducer from the power supply and the ground, respectively, to float the driving electrode and the ground electrode of the ultrasonic transducer during a second time period based on the received drive signal to store a charge between the driving electrode to the ground electrode.

Various exemplary embodiments relate to a device to measure carbon dioxide (CO.sub.2) levels, including a first oscillator group comprising a first sensor to measure air pressure, where the first sensor comprises a first sealed membrane, and where the first sealed membrane overlays a sealed first cavity; a second oscillator group including a second sensor to measure the resonance frequency of a second unsealed oscillating membrane, and where the second unsealed membrane overlays a second cavity in contact with the air outside of the second sensor; and a mixer accepting as input a first frequency measurement output from the first oscillator group and a second frequency measurement output from the second oscillator group, outputting the difference of the first frequency measurement and the second frequency measurement, and computing a carbon dioxide measurement based on the difference.

An electrostatic capacitance type transducer includes one or more elements 2. The one or more elements each include a plurality of cell groups 14 each including a cell 1 including a first electrode 4 and a second electrode 5 arranged with a gap therebetween, the second electrode being electrically connected to a shared signal extraction electrode 15. In the cell group, each of the cells has an equal wiring length from the shared signal extraction electrode 15. The electrostatic capacitance of the plurality of cell groups, the wiring resistance between two adjacent cell groups, the number of cell groups in the element, and the central frequency of the element satisfy a predetermined relationship to increase transmission efficiency or reception sensitivity.

A detection circuit detects a signal output from an element that receives an acoustic wave. The detection circuit is configured so as not to conduct a detection operation during a period in which the element does not receive the acoustic wave.

A capacitive ultrasonic transducer includes a sensor head having a back plate, the structured front side of which is provided with an insulation layer, and the back side of which is provided with an electrode. In order to achieve an improved construction by means of which increased temperature resistance up to several hundred degrees Celsius can be achieved even in strongly oxidizing and reducing media, the membrane provided as a sound generator is subjected to tensile stress in a planar direction.

An apparatus includes a transducer array with a plurality of CMUT elements. Each of the plurality of CMUT elements includes a first end and a second end. The transducer array further includes a bias network that is electrically connected with the first and second ends of the plurality of CMUT elements. The bias network applies a first bias voltage to the first end of the plurality of CMUT elements and a second bias voltage to the second end of the plurality of CMUT elements. The first and second bias voltages bias the plurality of CMUT elements. A method includes biasing, with bias network, a CMUT element of an transducer array using a bipolar signal that includes a first bias voltage and a second bias voltage, transmitting, by a transmit circuit, a transmit signal to the CMUT element, receiving, by a receive circuit, a receive signal from the CMUT element.

To provide a photoacoustic probe capable of acquiring subject information for reducing generation of artifacts without increasing the number of wires connected to the outside. Provided is a probe including a plurality of ultrasonic transducers, wherein the ultrasonic transducers are divided into a plurality of groups, two adjoining ultrasonic transducers belong to different groups, and the probe includes a group selection unit configured to switch signals of the ultrasonic transducers to be outputtable for each of the groups.

Aspects of the technology described herein relate to a capacitive micromachined ultrasonic transducer (CMUT) and a heater disposed in the CMUT, and forming a capacitive micromachined ultrasonic transducer (CMUT) and a heater disposed in the CMUT. A voltage may be applied to a heater disposed in a CMUT in an ultrasound imaging device in order to cause the heater to generate heat. Based on determining that the collapse voltage of the CMUT has increased by at least a threshold voltage between two times, a voltage may be automatically applied to a heater in the CMUT such that the heater generates heat.