Acoustic micro-sensors have already been applied in mass sensing including surface acoustic wave (SAW), flexural plate wave (FPW), thickness shear mode (TSM) and shear horizontal acoustic plate mode (SH-APM). The FPW micro-sensor is very suitable for liquid-sensing and bio-sensing applications due to the high mass-sensitivity and low phase-velocity in liquid. However, the conventional FPW micro-sensors presented a high insertion-loss (IL) and a low signal-to-noise ratio so it is difficult to combine with IC into a micro-system. To overcome these drawbacks, this study combine the Microelectromechanical System (MEMS) technology and the high C-axis orientation ZnO piezoelectric thin-film to develop a low insertion loss, low operation frequency, and high electromechanical coupling coefficient FPW device. In this study, a high C-axis orientation ZnO piezoelectric thin-film with a 20944A.U. X-Ray diffraction intensity at 34.200 degree and a 0.573 degree full width at half maximum (FWHM) was deposited by a commercial magnetic radio-frequency (RF) sputter system. The total processes of the FPW micro-sensor included five photolithography and seven thin-film depositions. In this study a low operation frequency (0.1MHz), low insertion loss (11dB to 14dB) and high electromechanical coupling coefficient (11%) FPW sensor was developed and fabricated.

Orientador: Diana Rodrigues de Pina / Resumo: A enterocolite necrosante (NEC – do inglês necrotizing enterocolitis) é caracterizada pela necrose isquêmica da mucosa intestinal de recém-nascidos prematuros. Uma vez que existe a suspeita de NEC, é instituída uma rotina de radiografias abdominais de acordo com a gravidade da doença. Os principais achados radiológicos de pacientes com NEC são: distensão abdominal generalizada, pneumatose intestinal, pneumoperitônio. Entretanto, a interpretação dessas radiografias é um processo difícil devido à falta de especificidade da maioria dos achados radiológicos. O objetivo desse estudo foi desenvolver uma ferramenta computacional que auxilie o corpo clínico na análise de radiografias abdominais para a diferenciação de alças normais e alças inflamadas em recém-nascidos prematuros. Para o desenvolvimento desta pesquisa foi utilizado um banco de dados composto por 45 radiografias abdominais e algoritmos computacionais desenvolvidos em ambiente MatLab. As espessuras das alças intestinais foram quantificadas através da ferramenta computacional Largura a Meia Altura (FWHM – do inglês Full Width at Half Maximum), e classificadas como alças edemaciadas ou alças normais. Para a análise de textura e extração de características, a fim de diferenciar regiões de pneumatose, aplicamos a técnica de Transformada Wavelet. Com a utilização do algoritmo, as alças intestinais normais apresentaram mediana igual a 10,30 pixels, enquanto as alças edemaciadas, foram estatisticamente maiores (Mann Whitney, p... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre

Compared with the detector devices made of inorganic semiconductors, organic photodetectors are granted with additional strengths, such as flexibility, high scalability and bio-compatibility. However, in the family of organic optoelectronic devices, the detectors that are capable of detecting photons at two or multiple specific wavelengths are still missing. Such photodetectors are highly interesting because they could identify the target objects or materials much more precisely by detecting the reflected, transmitted or emitted photons at two or multiple characteristic wavelengths. In this thesis project, the optical simulations using Transfer Matrix Method (TMM) were performed on the organic devices to achieve the dual wavelength narrowband detection in the near-infrared (NIR) spectral range of 700 ~ 1100 nm. The devices use the fact that, at the interface of the blended organic electron donating and accepting materials, the charge-transfer (CT) states with the transition energies that are lower than the optical gap of the neat materials are formed. Combined with a Fabry-Perot resonant cavity, the CT absorption can be dramatically enhanced at certain wavelengths. The simulation results show that the two detection wavelengths can be tuned independently from 650 to 1100 nm. The spectral resolution (full with at half maximum - FWHM) of the detection bands varies between 10 and 30 nm. The simulated external quantum efficiency (EQE) is ~35% at 700 nm and ~10% at 1000 nm, respectively. A possible application of such photodetectors is for example moisture detection, where two of the characteristic absorption peaks of water are located at around 750 and 960 nm. By optimizing the thickness of the two photo-absorbing layers in a tandem device structure, the detection bands can be tuned to match with those two wavelengths for simultaneous and precise detection.