@inproceedings{TsujiKupnikKhuriYakub, author = {Tsuji, Yukihide and Kupnik, Mario and Khuri-Yakub, Butrus T.}, title = {Low temperature process for CMUT fabrication with wafer bonding technique}, series = {2010 IEEE International Ultrasonics Symposium (IUS 2010), San Diego, California, USA, 11 - 14 October 2010}, booktitle = {2010 IEEE International Ultrasonics Symposium (IUS 2010), San Diego, California, USA, 11 - 14 October 2010}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-4577-0381-2}, pages = {551 -- 554}, language = {en} } @inproceedings{WygantKupnikKhuriYakub, author = {Wygant, Ira O. and Kupnik, Mario and Khuri-Yakub, Butrus T.}, title = {Design, Fabrication, and Design Verification of 50-kHz CMUTs for High-Intensity Airborne Ultrasound}, series = {20th International Congress on Acoustics 2010 (ICA 2010), Sydney, Australia, 23 - 27 August 2010, Vol. 2}, booktitle = {20th International Congress on Acoustics 2010 (ICA 2010), Sydney, Australia, 23 - 27 August 2010, Vol. 2}, publisher = {Curran}, address = {Red Hook, NY}, pages = {S. 1067}, language = {en} } @inproceedings{ParkKupnikLeeetal., author = {Park, Kwan Kyu and Kupnik, Mario and Lee, Hyunjoo J. and Oralkan, {\"O}mer and Khuri-Yakub, Butrus T.}, title = {Zero-bias resonant sensor with an oxide-nitride layer as charge trap}, series = {2010 IEEE sensors, Waikoloa, Hawaii, USA, 1 - 4 November 2010}, booktitle = {2010 IEEE sensors, Waikoloa, Hawaii, USA, 1 - 4 November 2010}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-4244-8168-2}, pages = {1024 -- 1028}, language = {en} } @inproceedings{ParkKupnikLeeetal., author = {Park, Kwan Kyu and Kupnik, Mario and Lee, Hyunjoo J. and Khuri-Yakub, Butrus T.}, title = {Modeling CMUT of multi-cell configuration}, series = {IEEE Ultrasonics Symposium (IUS), 2010, 11 - 14 Oct. 2010, Town \& Country Inn \& Convention Center, San Diego}, booktitle = {IEEE Ultrasonics Symposium (IUS), 2010, 11 - 14 Oct. 2010, Town \& Country Inn \& Convention Center, San Diego}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-4577-0381-2}, pages = {431 -- 434}, language = {en} } @inproceedings{HoffmannUngerHoetal., author = {Hoffmann, Maik and Unger, Alexander and Ho, Min-Chieh and Park, Kwan Kyu and Khuri-Yakub, Butrus T. and Kupnik, Mario}, title = {Volumetric characterization of ultrasonic transducers for gas flow metering}, series = {Proceedings, 2013 IEEE International Ultrasonics Symposium}, booktitle = {Proceedings, 2013 IEEE International Ultrasonics Symposium}, publisher = {IEEE}, doi = {10.1109/ULTSYM.2013.0336}, pages = {1315 -- 1318}, abstract = {The design of ultrasonic gas flowmeters requires a thorough three dimensional characterization of the acoustic sound field. For large pipe flowmeters, such as used for flare gas metering, the transducers are operated at frequencies ranging from 20 kHz up to 150 kHz. Thus, in this work we use a commercially available calibrated 1/8-inch microphone, mounted on a 3D positioning system for performing volumetric measurements in a volume of up to 1x1x1 m. By using proper corrections in terms of angular and free-field response of the microphone, the measurement system is efficient and delivers around 30000 measurements in about only eight hours. The data then is visualized in form of 3D figures or various slices to extract all relevant information. The system has been used to identify non-uniform velocity profiles in capacitive micromachined ultrasonic transducers (CMUTs), operating in permanent contact mode. Further, the system can be used to investigate the effect of various acoustic boundary conditions the transducers are facing when mounted inside transducer port cavities and it can be used for general model validation purpose.}, language = {en} } @inproceedings{UngerHoffmannHoetal., author = {Unger, Alexander and Hoffmann, Maik and Ho, Min-Chieh and Park, Kwan Kyu and Khuri-Yakub, Butrus T. and Kupnik, Mario}, title = {Finite element analysis of mechanically amplified CMUTs}, series = {Proceedings, 2013 IEEE International Ultrasonics Symposium}, booktitle = {Proceedings, 2013 IEEE International Ultrasonics Symposium}, publisher = {IEEE}, doi = {10.1109/ULTSYM.2013.0074}, pages = {287 -- 290}, abstract = {We introduce the possibility of improving a single-cell capacitive micromachined ultrasonic transducer (CMUT) for air-coupled ultrasound by simply adding a hollow conical-shaped structure (horn) on top of the CMUT plate. The main objective is to improve both transmit and receive sensitivity by lowering the center-to-average displacement ratio, which for bending plate operated devices inherently is limited. In addition, for receive mode the force generated from the impinging sound pressure wave is concentrated to the center of the plate, resulting in larger signals and, in contrast to piston-shaped plates, the horn has the advantage of only moderately increasing the modal mass of the structure. By using finite element analysis and first sound pressure measurements of our modified CMUT, we demonstrate that this idea is feasible and promising for air-coupled CMUTs operating at frequencies below 150kHz, as it has been been proven to be successful for commercially available piezoelectric - driven bending plate devices as well.}, language = {en} } @inproceedings{GolinskeHoffmannGuptaetal., author = {Golinske, Ren{\´e} and Hoffmann, Maik and Gupta, Abhinav and Kupnik, Mario}, title = {Calculation of diffraction loss between non-co-axial ultrasonic transducer configurations}, series = {Proceedings, 2013 IEEE International Ultrasonics Symposium}, booktitle = {Proceedings, 2013 IEEE International Ultrasonics Symposium}, doi = {10.1109/ULTSYM.2013.0555}, pages = {2171 -- 2174}, abstract = {We derive and validate a quadruple integral expression for calculating the diffraction loss in an isotropic propagation medium between circular ultrasonic transducers with time-harmonic radiation. The distinctive feature is the generic non-coaxial configuration with arbitrary transducer size and orientation. By performing several measurements, we validate the integral expression and we demonstrate that nowadays it is feasible to perform the required numerical integration to obtain the diffraction loss over an entire volumetric sound pressure field on a state-of-the-art personal computer with reasonable computation time on the order of a few minutes only. Excellent agreement between calculated results and experiments prove the approach and the generic nature of our expression ensures its wide and simple applicability for efficient diffraction loss calculations.}, language = {en} } @misc{KupnikKhuriYakub, author = {Kupnik, Mario and Khuri-Yakub, Butrus T.}, title = {Monolithic integrated CMUTs fabricated by low temperature wafer bonding}, abstract = {Low temperature wafer bonding (temperature of 450°C. or less) is employed to fabricate CMUTs on a wafer that already includes active electrical devices. The resulting structures are CMUT arrays integrated with active electronics by a low-temperature wafer bonding process.The use of a low-temperature process preserves the electronics during CMUT fabrication. With this approach, it is not necessary to make compromises in the CMUT or electronics designs, as is typical of the sacrificial release, such as low process control, poor design flexibility, low reproducibility, and reduced performance are avoided with the present approach. With this approach, a CMUT array can be provided with per-cell electrodes connected to the substrate integrated circuitry. This enables complete flexibility in electronically assigning the CMUT cells to CMUT array elements.}, language = {en} } @misc{KupnikKhuriYakub, author = {Kupnik, Mario and Khuri-Yakub, Butrus T.}, title = {Sensor for measuring properties of liquids and gases}, abstract = {The present invention provides a device that measures at least one property of the liquid or gas, where the invention is a CMUT sensor that includes a substrate, a first layer disposed on the substrate, where the first layer includes a cavity, and a compound plate, where the compound plated includes a bottom plate, an intermediate plate and a top plate. According to the invention, the intermediate plate has at least one sample inlet, a sample cavity and at least one sample outlet, where the bottom plate is disposed on the first layer, and the cavity in the first layer is sealed by the compound plate. The cavity in the first layer can be a vacuum or contain a gas. The CMUT sensor can be disposed in an array of two or more sensors and connected electrically in parallel.}, language = {en} } @misc{LeeParkKupniketal., author = {Lee, Hyunjoo J. and Park, Kwan Kyu and Kupnik, Mario and Melosh, Nicholas A. and Khuri-Yakub, Butrus T.}, title = {Mesoporous thin-film on highly sensitive resonant chemical sensors for relative humidity and CO2 detection}, series = {Analytical Chemistry}, volume = {84}, journal = {Analytical Chemistry}, number = {7}, issn = {1520-6882}, doi = {10.1021/ac300225c}, pages = {3063 -- 3066}, abstract = {Distributed sensing of gas-phase chemicals is a promising application for mesoporous materials when combined with highly sensitive miniaturized gas sensors. We present a direct application of a mesoporous silica thin film on a highly sensitive miniaturized resonant chemical sensor with a mass sensitivity at the zeptogram scale for relative humidity and CO2 detection. Using mesoporous silica thin-film, we report one of the lowest volume resolutions and a sensitive detection of 5.1 × 10-4\% RH/Hz to water vapor in N2, which is 70 times higher than a device with a nontemplated silica layer. In addition, a mesoporous thin-film that is functionalized with an amino-group is directly applied on the resonant sensor, which exhibits a volume sensitivity of 1.6 × 10-4\%/Hz and a volume resolution of 1.82 × 10-4\% to CO2 in N2.}, language = {en} }