Capacitive micromachined ultrasonic transducer arrays incorporating anodically bondable low temperature co‐fired ceramic for small diameter ultrasonic endoscope

Yildiz, Fikret; Matsunaga, Tadao; Haga, Yoichi

doi:10.1049/mnl.2016.0281

Cited by 11 publications

(8 citation statements)

References 20 publications

(24 reference statements)

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“…Squeezed film damping in sealed cavity was omitted for modelling, because it was analytically proved from a previous study that the presence of air does not cause any squeeze film damping for flexural membrane [50]. Resonance frequency and maximum membrane displacement were obtained as 1.5755 MHz and 2.42 pm according to the numerical analysis as shown in Figure 7 [44]. Experimental results of the impedance measurement are shown in Figure 8a.…”

Section: Resultsmentioning

confidence: 94%

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Nanostructure Based Sensors for Gas Sensing: from Devices to Systems

Donato¹,

Grassini²

2019

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He is currently an Associate Professor of Electrical and Electronic Measurements and the head of the laboratories of "Electronics for Sensors and for Systems of Transduction" and of "Electrical and Electronic Measurements" at University of Messina. He has authored over 150 papers on international journals and conference proceedings (Scopus). His current research interests include sensor characterization and modeling, development of measurement system for sensors, and characterization of electronic devices up to microwave range and downto criogenic temperatures. Sabrina Grassini received the M.S. degree in chemistry from the University of Torino, Turin, Italy, in 1999, and the Ph.D. degree in metallurgical engineering from the Politecnico di Torino, Turin, in 2004. In 2007, she joined the Politecnico di Torino as an Assistant Professor of chemistry and became an Associate Professor of applied physical chemistry with the Department of Applied Science and Technology in 2016. Her current research interests include chemical/physical fundamentals of plasma processes, the study of corrosion mechanisms of metals and alloys, conservation of cultural heritage, and sensors for environmental and medical measurements. She has authored more than 180 papers in national and international journals and in the proceedings of international conferences. vii micromachines EditorialAbstract: In this study, UV irradiation was used to improve the response of indium oxide (In 2 O 3 ) used as a CO sensing material for a resistive sensor operating in a low temperature range, from 25 • C to 150 • C. Different experimental conditions have been compared, varying UV irradiation mode and sensor operating temperature. Results demonstrated that operating the sensor under continuous UV radiation did not improve the response to target gas. The most advantageous condition was obtained when the UV LED irradiated the sensor in regeneration and was turned off during CO detection. In this operating mode, the semiconductor layer showed an apparent "p-type" behavior due to the UV irradiation. Overall, the effect was an improvement of the indium oxide response at 100 • C toward low CO concentrations (from 1 to 10 ppm) that showed higher results than in the dark, which is promising to extend the detection of CO with an In 2 O 3 -based sensor in the sub-ppm range.Abstract: Bad breath or halitosis affects a majority of the population from time to time, causing personal discomfort and social embarrassment. Here, we report on a miniaturized, microelectromechanical systems (MEMS)-based, amperometric hydrogen sulfide (H 2 S) sensor that potentially allows bad breath quantification through a small handheld device. The sensor is designed to detect H 2 S gas in the order of parts-per-billion (ppb) and has a measured sensitivity of 0.65 nA/ppb with a response time of 21 s. The sensor was found to be selective to NO and NH 3 gases, which are normally present in the oral breath of adults. The ppb-level detection capability of the integrated sensor, combined with its rel...

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Section: Resultsmentioning

confidence: 94%

“…A narrower via pitch fabrication is easier than when using a glass substrate, and also LTCC allows freedom in via design [40][41][42][43]. Recently, SOI-LTCC anodic bonding has been announced for CMUT fabrication [24,44,45]. In these studies, CMUTs were built directly on open tool and customized LTCC substrate.…”

Section: Introductionmentioning

confidence: 99%

Nanostructure Based Sensors for Gas Sensing: from Devices to Systems

Donato¹,

Grassini²

2019

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“…Squeezed film damping in sealed cavity was omitted for modelling, because it was analytically proved from a previous study that the presence of air does not cause any squeeze film damping for flexural membrane [ 50 ]. Resonance frequency and maximum membrane displacement were obtained as 1.5755 MHz and 2.42 pm according to the numerical analysis as shown in Figure 7 [ 44 ].…”

Section: Resultsmentioning

confidence: 99%

“…Fabricated CMUTs were characterized in air and immersion medium. More details about LTCC-SOI bonding process flow have been given in our previous studies [ 44 ].…”

Section: Methodsmentioning

confidence: 99%

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Fabrication and Packaging of CMUT Using Low Temperature Co-Fired Ceramic

2018

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This paper presents fabrication and packaging of a capacitive micromachined ultrasonic transducer (CMUT) using anodically bondable low temperature co-fired ceramic (LTCC). Anodic bonding of LTCC with Au vias-silicon on insulator (SOI) has been used to fabricate CMUTs with different membrane radii, 24 µm, 25 µm, 36 µm, 40 µm and 60 µm. Bottom electrodes were directly patterned on remained vias after wet etching of LTCC vias. CMUT cavities and Au bumps were micromachined on the Si part of the SOI wafer. This high conductive Si was also used as top electrode. Electrical connections between the top and bottom of the CMUT were achieved by Au-Au bonding of wet etched LTCC vias and bumps during anodic bonding. Three key parameters, infrared images, complex admittance plots, and static membrane displacement, were used to evaluate bonding success. CMUTs with a membrane thickness of 2.6 µm were fabricated for experimental analyses. A novel CMUT-IC packaging process has been described following the fabrication process. This process enables indirect packaging of the CMUT and integrated circuit (IC) using a lateral side via of LTCC. Lateral side vias were obtained by micromachining of fabricated CMUTs and used to drive CMUTs elements. Connection electrodes are patterned on LTCC side via and a catheter was assembled at the backside of the CMUT. The IC was mounted on the bonding pad on the catheter by a flip-chip bonding process. Bonding performance was evaluated by measurement of bond resistance between pads on the IC and catheter. This study demonstrates that the LTCC and LTCC side vias scheme can be a potential approach for high density CMUT array fabrication and indirect integration of CMUT-IC for miniature size packaging, which eliminates problems related with direct integration.

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