@misc{LeeParkKupniketal., author = {Lee, Hyunjoo J. and Park, Kwan Kyu and Kupnik, Mario and Khuri-Yakub, Butrus T.}, title = {Functionalization layers for CO2 sensing using capacitive micromachined ultrasonic transducers}, series = {Sensors and Actuators B: Chemical}, journal = {Sensors and Actuators B: Chemical}, number = {174}, issn = {0925-4005}, pages = {87 -- 93}, abstract = {Sensing of carbon dioxide(CO2)using inexpensive, miniaturized,and highly sensitive sensors is of great interest for environmental and consumer applications. In this paper, we present four functionalization layers that are suitable for resonant sensors based on mass-loading for CO2 detection. We compare the volume sensitivities of these layers to CO2 and relative humidity (RH) by using a highly sensitive 50-MHz capacitive micromachined ultrasonic transducer (CMUT) as a resonant sensor. Among the four function-alization layers, the layer based on a guanidine polymer exhibits the highest volume sensitivity to CO2 of 1.0 ppm/Hz in N2 and 3.8 ppm/Hz in air (∼45\%RH). Furthermore, we report on other important characteristics of the guanidine polymer for sensing applications, including polymer saturation, regeneration, and repeatability.}, 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} } @misc{ParkLeeKupniketal., author = {Park, Kwan Kyu and Lee, Hyunjoo J. and Kupnik, Mario and Oralkan, {\"O}mer and Ramseyer, Jean-Pierre and Lang, Hans Peter and Hegner, Martin and Gerber, Christoph and Khuri-Yakub, Butrus T.}, title = {Capacitive micromachined ultrasonic transducer (CMUT) as a chemical sensor for DMMP detection}, series = {Sensors and Actuators B: Chemical}, volume = {160}, journal = {Sensors and Actuators B: Chemical}, number = {1}, issn = {0925-4005}, doi = {10.1016/j.snb.2011.09.036}, pages = {1120 -- 1127}, language = {en} } @misc{ParkLeeKupniketal., author = {Park, Kwan Kyu and Lee, Hyunjoo J. and Kupnik, Mario and Khuri-Yakub, Butrus T.}, title = {Fabrication of capacitive micromachined ultrasonic transducers via local oxidation and direct wafer bonding}, series = {Journal of Microelectromechanical Systems}, volume = {20}, journal = {Journal of Microelectromechanical Systems}, number = {1}, issn = {1941-0158}, doi = {10.1109/JMEMS.2010.2093567}, pages = {95 -- 103}, language = {en} } @misc{LeeParkKupniketal., author = {Lee, Hyunjoo J. and Park, Kwan Kyu and Kupnik, Mario and Oralkan, {\"O}mer and Khuri-Yakub, Butrus T.}, title = {Chemical vapor detection using a capacitive micromachined ultrasonic transducer}, series = {Analytical chemistry}, volume = {83}, journal = {Analytical chemistry}, number = {24}, issn = {1520-6882}, doi = {10.1021/ac201626b}, pages = {9314 -- 9320}, language = {en} } @inproceedings{LeeParkKupniketal., author = {Lee, Hyunjoo J. and Park, Kwan Kyu and Kupnik, Mario and Oralkan, {\"O}mer and Khuri-Yakub, Butrus T.}, title = {Highly sensitive detection of DMMP using a CMUT chemical sensor}, series = {2010 IEEE sensors, Waikoloa, Hawaii, USA, 1 - 4 November 2010, the Ninth IEEE Sensors Conference 2010}, booktitle = {2010 IEEE sensors, Waikoloa, Hawaii, USA, 1 - 4 November 2010, the Ninth IEEE Sensors Conference 2010}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-4244-8168-2}, doi = {10.1109/ICSENS.2010.5690493}, pages = {2122 -- 2126}, 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} }