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A top-crossover-to-bottom addressed segmented annular array using piezoelectric micromachined ultrasonic transducers

A top-crossover-to-bottom addressed segmented annular array using piezoelectric micromachined ultrasonic transducers
Jung, JoontaekLee, WonjunKang, WoojinHong, HyeryungSong, Hi YuenOh, Inn-yealPark, Chul SoonChoi, Hongsoo
DGIST Authors
Jung, JoontaekLee, WonjunKang, WoojinChoi, Hongsoo
Issued Date
Article Type
Acoustic ImpedanceAcoustic TransducersAnisotropic Silicon EtchingAnnular ArrayCapacitanceDeep Reactive Ion EtchingElectrodesFerroelectric CeramicsLead Zirconate TitanateMEMSMicro-Machined Ultrasonic TransducerMicrostrip LinesNatural FrequenciesParasitic CapacitancePiezoelectric Micromachined Ultrasonic Transducers (PMUTs)Piezoelectric TransducersPiezoelectricityPrinted Circuit BoardsPrinted CircuitsReactive Ion EtchingSegmented Annular ArraysSemiconducting Lead CompoundsSilicon WafersSol-GelsTransducersUltrasonic IntensityUltrasonic RadiationUltrasonic Transducers
We design and fabricate segmented annular arrays (SAAs) using piezoelectric micromachined ultrasonic transducers (pMUTs) to demonstrate the feasibility of acoustic focusing of ultrasound. The fabricated SAAs have 25 concentric top-electrode signal lines and eight bottom-electrodes for grounding to enable electronic steering of selectively grouped ultrasonic transducers from 2393 pMUT elements. Each element in the array is connected by top-crossover-to-bottom metal bridges, which reduce the parasitic capacitance. Circular-shaped pMUT elements, 120 μm in diameter, are fabricated using 1 μm-thick sol-gel lead zirconate titanate on a silicon wafer. To utilize the high-density pMUT array, a deep reactive ion etching process is used for anisotropic silicon etching to realize the transducer membranes. The resonant frequency and effective coupling coefficient of the elements, measured with an impedance analyzer, yields 1.517 MHz and 1.29%, respectively, in air. The SAAs using pMUTs are packaged on a printed circuit board and coated with parylene C for acoustic intensity measurements in water. The ultrasound generated by each segmented array is focused on a selected point in space. When a 5 Vpp, 1.5 MHz square wave is applied, the maximum spatial peak temporal average intensity () is found to be 79 mW cm-2 5 mm from the SAAs' surface without beamforming. The beam widths (-3 dB) of ultrasonic radiation patterns in the elevation and azimuth directions are recorded as 3 and 3.4 mm, respectively. The results successfully show the feasibility of focusing ultrasound on a small area with SAAs using pMUTs. © 2015 IOP Publishing Ltd.
Related Researcher
  • 최홍수 Choi, Hongsoo 로봇및기계전자공학과
  • Research Interests Micro/Nano robot; Neural prostheses; MEMS; BMI; MEMS/NEMS; BioMEMS; MEMS 초음파 트랜스듀스; 인공와우
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Department of Robotics and Mechatronics Engineering Bio-Micro Robotics Lab 1. Journal Articles


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