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 acoustic device for inspection of an object. The device includes an ultrasonic source including a snap-through buckling actuator. The device may be used for non-destructive testing of objects. The device may be carried by a platform, such as a coordinate measuring machine, to allow inspection of objects or it may be embedded within an object for life cycle monitoring purposes.

A system for evaluating a bond includes a first electrode and a second electrode that are spaced apart from one another. The system also includes a sacrificial material layer positioned proximate to a surface of a bonded structure that includes the bond. The system also includes a power source configured to cause the first and second electrodes to generate an electrical arc that at least partially ablates the sacrificial material layer as part of a non-destructive inspection of the bond.

A method for manufacturing a radio frequency (RF) applicator which includes covering a ceramic insert with a coating, wherein the ceramic insert has dimensions that substantially match an internal volume of an open-ended, hollow waveguide, and wherein the ceramic insert has a recess therein configured to accept a radio frequency emitter, heating the waveguide to a temperature that is above a melting point of the coating, placing the coated ceramic insert into the internal volume of the heated waveguide, wherein the internal volume is completely filled except for the recess, and cooling the waveguide, ceramic insert, and coating to a temperature below the melting point of the coating so that the coating solidifies and fills gaps between facing surfaces of the insert and the waveguide.

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.

In an embodiment an electro-thermal device includes a heater, a readout circuit, a digital controller having a first input coupled to a first output of the readout circuit and a digital sigma-delta modulator having a first input coupled to an output of the digital controller and an output coupled to the heater.

A system and method for evaluating a bond is provided. The system uses an underwater spark discharge to generate a compression wave in a first vessel containing a liquid. The system further includes a second vessel in which a vacuum is pulled to hold the first vessel against a bonded structure being inspected. The compression wave is directed to propagate from the liquid into the bonded structure to apply a known force to the bond being inspected.

A method for evaluating a target, the target having a surface, includes pulsing a defined, energetic particle beam through the surface and into the target such that particle energy deposition from the particle beam is concentrated in a subsurface target volume within a target medium of the target. The deposited particle energy induces a thermoelastic expansion of the target medium in the target volume that generates a corresponding acoustic wave. The method further includes detecting the acoustic wave from the target medium.

Provided is an apparatus with a gas detection function capable of detecting a detection target gas with high accuracy. An apparatus with a gas detection function comprises: a housing (10); a vibration source (20); and a gas measurement unit (40) located inside the housing and demarcated by a partition, wherein the vibration source is located outside the gas measurement unit, the gas measurement unit includes a detector (41) located on a substrate (30), and a gas detection space (42) provided with a hole (43) through which a gas passes, and a frequency f expressed by the following Formula (1):

[00001]$\begin{array}{cc}f=\frac{c}{2\pi }\sqrt{\frac{S}{\mathrm{VL}}}& \mathrm{Formula}\left(1\right)\end{array}$ is 500 Hz or more, where V is a volume of the gas detection space, S is a cross-sectional area of the hole, L is an effective length of the hole, and c is a sound speed.

In an embodiment an electro-thermal device includes a heater, a readout circuit, a digital controller having a first input coupled to a first output of the readout circuit and a digital sigma-delta modulator having a first input coupled to an output of the digital controller and an output coupled to the heater.