Development of a high-density piezoelectric micromachined ultrasonic transducer array based on patterned aluminum nitride thin film

This study presents the fabrication and characterization of a piezoelectric micromachined ultrasonic transducer (pMUT; radius: 40 μm) using a patterned aluminum nitride (AlN) thin film as the active piezoelectric material. A 20 x 20 array of pMUTs using a 1 μm thick AlN thin film was designed and fabricated on a 2 x 2 mm2 footprint for a high fill factor. Based on the electrical impedance and phase of the pMUT array, the electromechanical coefficient was ~1.7% at the average resonant frequency of 2.82 MHz in air. Dynamic displacement of the pMUT surface was characterized by scanning laser Doppler vibrometry. The pressure output while immersed in water was 19.79 kPa when calculated based on the peak displacement at the resonant frequency. The proposed AlN pMUT array has potential applications in biomedical sensing for healthcare, medical imaging, and biometrics. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.1

Development of a micro-electro-mechanical systems (MEMS) vector sensor with mushroom-shaped proof mass and characterization of its properties as a hydrophone

Micro-electro-mechanical systems (MEMS), Piezoelectric, Vector sensor, HydrophoneMicro-electro-mechanical-systems (MEMS) underwater vector sensors are capable of detecting the distance and the direction of sound signals generated by an underwater target. In this research, a piezoelectric MEMS vector sensor, which has four-clamped beams with a mushroom-shaped proof mass to improve receiving voltage sensitivity (RVS), was designed, fabricated and tested. In the design stage, two different designs were proposed and simulations were carried out using COMSOL Multiphysics® software to optimize the design parameters such as the beam length and the weight of the proof mass, which affect the resonance frequency. Based on the simulation results, the piezoelectric Pb(Zr¬0.52Ti0.48)O3 thin film was deposited by radio frequency (RF) magnetron sputtering and placed between two bottom and top platinum electrodes. The optimized fabrication process involved multiple etching steps and assembly process with mass structure. To investigate its performance as a MEMS vector sensor, its electrical and mechanical properties were characterized and the device showed promising results in resonance frequency and displacement when measured in air, although additional underwater experiments need to be conducted using theoretical algorithms to figure out the directivity in order to evaluate its capability as a hydrophone.prohibitionList of Contents Abstract List of Contents List of Figures List of Tables 1. Introduction 1 1.1 Hydrophone 1 1.2 Piezoelectric microelectromechanical system 2 1.2.1 Piezoelectric effect 2 1.2.2 Piezoelectric MEMS 6 1.3 Literature reviews 7 1.3.1 Piezoresistive MEMS hydrophone 7 1.3.2 Piezoelectric MEMS hydrophone 9 1.3.3 Piezoelectric device operating space 10 1.3.4 Stress distribution of clamped beam microstructure 11 1.4 Aim and objectives 14 2. Design and fabrication 15 2.1 Device concept and design 15 2.2 Simulation for optimization of design parameters 17 2.3 Fabrication process 10 2.3.1 Assembly with mass components 22 2.4 Packaging 23 3. Experimental methods 24 3.1 Experiment setup for measuring electrical properties 25 3.2 Experiment setup for measuring mechanical properties 25 4. Results and discussion 27 4.1 Fabrication results and discussion 27 4.2 Experimental results 42 4.2.1 Characteristics of microstructure 42 4.2.2 Electrical properties 43 4.2.3 Mechanical properties 47 4.2.4 Characteristics of PMVH devices with mushroom-shaped proof mass 52 5. Conclusions and future work 60 References 61 Appendices 67 요약문 70미세전자기계시스템 (Micro-electro-mechanical-systems) 기반의 수중 음향 벡터 센서는 일반적으로 수중의 표적이 생성한 음파를 이용하여 타겟까지의 거리와 방향을 감지한다. 본 연구에서 수신 전압 강도 (RVS)를 향상시키기 위해 버섯 모양의 질량체와 4개의 고정된 빔을 갖는 압전 수중 음향 벡터 센서가 설계되고 제작되었다. 디자인 단계에서는 두개의 디자인이 제안 되었으며, 두가지 디자인의 센서를 비교하여 수신 전압 강도를 향상시키기 위한 최적화된 디자인을 구현하고자 한다. COMSOL Multiphysics® 소프트웨어를 사용하여 시뮬레이션을 수행하였고, 이를 통해 센서의 빔 길이와 너비 및 공진주파수를 결정하는 질량체의 무게와 같은 설계 매개 변수를 최적화 하였다. 미세전자기계시스템 기반의 압전 벡터 센서에 대한 시뮬레이션 결과에 기초하여, 압전 박막 (Pb(Zr¬0.52Ti0.48)O3) 은 고주파 마그네트론 스퍼터링 (RF magnetron sputtering) 에 의해 고정된 빔 위에 성공적으로 증착 되었고, 2개의 하부 및 상부 백금 전극 사이에 배치되었다. 또한 10 μm의 얇은 4개의 고정된 빔을 제작하기 위해 수행되는 다수의 식각 공정 및 조립 공정 과정을 최적화 하였다. 최적화된 음향 벡터 센서로서의 성능을 평가하기 위해, 유전 상수와 손실, 공진주파수 등을 측정함으로써 전기적 및 기계적 특성을 특성화 하였다. 또한 미세전자기계시스템 기반의 음향 벡터 센서는 음향 자극에 따라 공기에서 측정된 공명 주파수 및 변위를 포함하여 여러 요인에서 음향센서로서의 잠재성을 입증하였다. 하지만, 수중 음향 센서로서의 성능을 입증, 제안된 두개의 디자인을 비교 하기 위해서는 물 속에서 추가적인 실험이 필요하며, 이를 위해서는 수중에서 센서를 사용할 수 있는 패키징과 지향성을 찾기 위한 이론적 알고리즘의 구축이 필요하다.MasterdCollectio

A piezoelectric micro-electro-mechanical system vector sensor with a mushroom-shaped proof mass for a dipole beam pattern

Vector hydrophones based on a micro-electro-mechanical system (MEMS) hold great promise for underwater communications, due to their potential for miniaturization and mass production. Piezoelectric materials have recently been utilized in the fabrication of MEMS-based vector hydrophones, as less power is typically required for their operation. Here, we propose a millimeter-scale piezoelectric MEMS vector sensor with a suspended cross-shaped beam and a mushroom-shaped proof mass configuration. This design was inspired by the bio-transducer of the lateral line of fish. Sensor fabrication involved piezoelectric Pb(Zr0.52Ti0.48)O3 thin-film deposition by radio-frequency magnetron sputtering onto the beam structure, followed by a multi-etching process and assembly using a three-axis microassembly technique. The fabricated MEMS vector sensor showed a resonance frequency above the working frequency range, which was suitable for naval applications. The directivity of the proposed sensor was determined by dipole patterns in the x and y directions, with a maximum relative sensitivity difference of −42 dB at 1 kHz. Finite element analysis results for the resonance frequency and directivity were in good agreement with the experimental results, suggesting that the proposed vector sensor could be used in underwater communications as a vector hydrophone. © 2021 Elsevier B.V.1

Development of a High-Density Piezoelectric Micromachined Ultrasonic Transducer Array Based on Patterned Aluminum Nitride Thin Film

This study presents the fabrication and characterization of a piezoelectric micromachined ultrasonic transducer (pMUT; radius: 40 µm) using a patterned aluminum nitride (AlN) thin film as the active piezoelectric material. A 20 × 20 array of pMUTs using a 1 µm thick AlN thin film was designed and fabricated on a 2 × 2 mm2 footprint for a high fill factor. Based on the electrical impedance and phase of the pMUT array, the electromechanical coefficient was ~1.7% at the average resonant frequency of 2.82 MHz in air. Dynamic displacement of the pMUT surface was characterized by scanning laser Doppler vibrometry. The pressure output while immersed in water was 19.79 kPa when calculated based on the peak displacement at the resonant frequency. The proposed AlN pMUT array has potential applications in biomedical sensing for healthcare, medical imaging, and biometrics

DataSheet_1_Intranasal inoculation of IFN-λ resolves SARS-CoV-2 lung infection via the rapid reduction of viral burden and improvement of tissue damage.doc

IntroductionThe innate immune responses of upper airway could further our understanding toward antiviral strategies against SARS-CoV-2. We characterize the potential of interferon (IFN)-λ as an innate immune inducer for the rapid clearance of SARS-CoV-2 in the lung and the therapeutic efficacy of intranasal inoculation of IFN-λ to resolve acute lung infection.MethodsSyrian golden hamsters were infected with SARS-CoV-2 and the dynamics of SARS-CoV-2 infection depending on IFN-λ inoculation were tested.ResultsSARS-CoV-2-infected Syrian golden hamsters exhibited a significant decrease in body weight and high viral mRNA level at 3 days post-infection (dpi). Although viral replication was reduced completely from 7 dpi, the pathologic findings remained prominent until 14 dpi in the lung of hamsters. The transcription of IFN-λ was significantly induced in response to SARS-CoV-2 infection with the increase of IFN-stimulated genes. Intranasal inoculation of IFN-λ restricted SARS-CoV-2 replication in the lungs of infected completely from 3 dpi with markedly reduction of inflammatory cytokines. The transcriptional phenotypes were altered to the direction of damage repair and tissue remodeling in the lungs of SARS-CoV-2-infected hamsters following intranasal inoculation of IFN-λ, which improved SARS-CoV-2-caused lung damage.ConclusionCollectively, our findings suggest that IFN-λ might be a potent innate immune inducer in the lung and intranasal inoculation of IFN-λ resolves SARS-CoV-2 infection with rapid viral clearance and improvement of lung damage.</p

Synthesis of organic semiconductor bearing B←N bridged thienylthiazole and diketopyrrolopyrrole for the applicaton of high open-circuit voltage organic photovoltaics

New small molecular semiconductors with small band gap and low-lying highest occupied molecular orbital (EHOMO), namely TBDPPOT, TBDPPEH, and TBDPPEHT4 were synthesized by incorporating the B←N bridged thienylthiazole and diketopyrrolopyrrole (DPP) derivatives. TBDPPOT and TBDPPEH were prepared, respectively, using two different DPPs having 1-octyl and 2-ethylhexyl moiety as the solubilizing group. In addition, the band gap of the TBDPPEH is further reduced by introducing planar thienothiophene unit, which was used for the preparation of TBDPPEHT4. These synthesized SMs are blended with fullerene derivative to construct a photo-active layer for organic photovoltaics. Among OPVs utilizing those SMs, the TBDPPEH exhibits highest power conversion efficiency of 3.21% with an exceptionally high VOC of 0.92 V, which is ascribed to low-lying HOMO energy level of −5.62 eV. It is expected that the utilization of TBDPPEH as a photo-active layer for OPVs would enhance the oxidation stability of the OPVs. © 2017 Elsevier Ltd. All rights reserved.101sciescopu

An Electromagnetically Controllable Microrobotic Interventional System for Targeted, Real-Time Cardiovascular Intervention

Robotic magnetic manipulation systems offer a wide range of potential benefits in medical fields, such as precise and selective manipulation of magnetically responsive instruments in difficult-to-reach vessels and tissues. However, more preclinical/clinical studies are necessary before robotic magnetic interventional systems can be widely adopted. In this study, a clinically translatable, electromagnetically controllable microrobotic interventional system (ECMIS) that assists a physician in remotely manipulating and controlling microdiameter guidewires in real time, is reported. The ECMIS comprises a microrobotic guidewire capable of active magnetic steering under low-strength magnetic fields, a human-scale electromagnetic actuation (EMA) system, a biplane X-ray imaging system, and a remote guidewire/catheter advancer unit. The proposed ECMIS demonstrates targeted real-time cardiovascular interventions in vascular phantoms through precise and rapid control of the microrobotic guidewire under EMA. Further, the potential clinical effectiveness of the ECMIS for real-time cardiovascular interventions is investigated through preclinical studies in coronary, iliac, and renal arteries of swine models in vivo, where the magnetic steering of the microrobotic guidewire and control of other ECMIS modules are teleoperated by operators in a separate control booth with X-ray shielding. The proposed ECMIS can help medical physicians optimally manipulate interventional devices such as guidewires under minimal radiation exposure. © 2022 Wiley-VCH GmbHFALS

Carnuntum. Roman city on Danube (1st - 4th Century AD)

This thesis deals with questions of urban development in the Roman city of Camuntum. The main foeus is foremost to specify and review the global strueture of settlement, urbanism and civilian architecture during the first four hunderts AD. In the first chapters provide an overview of loeation and historical situation of Camuntum. In the following chapters the description of the urban settlement is divided jnto "civilian" and , "military" territory. including description of several archaeologieal findings and monuments, maily publie buildings and religious areas. Furthermore, questions related to typology of dwelling-houses and their interior have not been omitted. The thesis also tries to summarize other topics associated with the area of Roman provinees, for example trade and burialground. The last part of the thesis is devoted to comparison and parallels with other important sites in the area of Rhine and Danube

The Quantified Level of Circulating Prostate Stem Cell Antigen mRNA relative to GAPDH Level Is a Clinically Significant Indictor for Predicting Biochemical Recurrence in Prostate Cancer Patients after Radical Prostatectomy

The study quantified the relative absolute PSCA level in relation to the glyceraldehyde 3-phosphate dehydrogenase (GAPDH) level in the peripheral blood of 478 hormone-naive prostate cancer (PC) patients who underwent radical prostatectomy from 2005 to 2012 and evaluated its prognostic significance as a risk factor for predicting biochemical recurrence (BCR), compared to known parameters. Nested real-time polymerase chain reaction (RT-PCR) and gel electrophoresis detected PSCA levels and measured the PSCA/GAPDH ratio. Clinicopathological data from the institutional database were examined to determine the adequate cut-off level to predict postoperative BCR. A total of 110 patients had a positive PSCA result (23.0%) via RT-PCR (mean blood ratio 1.1 ± 0.4). The BCR was significantly higher in the PSCA-positive detection group (p=0.009). A multivariate model was created to show that a PSCA/GAPDH ratio between 1.0 and 1.5 (HR 12.722), clinical T2c stage (HR 0.104), preoperative PSA (HR 1.225), extraprostatic capsule extension (HR 0.006), lymph node dissection (HR 16.437), and positive resection margin (HR 27.453) were significant predictive factors for BCR (p<0.05). The study showed successful quantification of PSCA with its significance for BCR-related risk factor; however, further studies are needed to confirm its clinical predictive value