Development of a New Surface Acoustic Wave Based Gyroscope on a X-112°Y LiTaO3 Substrate

A new micro gyroscope based on the surface acoustic wave (SAW) gyroscopic effect was developed. The SAW gyroscopic effect is investigated by applying the surface effective permittivity method in the regime of small ratios of the rotation velocity and the frequency of the SAW. The theoretical analysis indicates that the larger velocity shift was observed from the rotated X-112°Y LiTaO3 substrate. Then, two SAW delay lines with reverse direction and an operation frequency of 160 MHz are fabricated on a same X-112°Y LiTaO3 chip as the feedback of two SAW oscillators, which act as the sensor element. The single-phase unidirectional transducer (SPUDT) and combed transducers were used to structure the delay lines to improve the frequency stability of the oscillator. The rotation of a piezoelectric medium gives rise to a shift of the propagation velocity of SAW due to the Coriolis force, resulting in the frequency shift of the SAW device, and hence, the evaluation of the sensor performance. Meanwhile, the differential structure was performed to double the sensitivity and compensate for the temperature effects. Using a precise rate table, the performance of the fabricated SAW gyroscope was evaluated experimentally. A sensitivity of 1.332 Hz deg−1 s at angular rates of up to 1,000 deg s−1 and good linearity are observed

LOCALIZED LASER VAPORIZATION OF FILMS WITH COMPLEX TOPOLOGIES FOR SURFACE ACOUSTIC WAVE MICROGYROSCOPE SENSOR

We have developed a method for localized laser vaporization of a sensitive element film for a solid microgyroscope based on surface acoustic waves. A double-conversion scheme was chosen as a microgyroscope sensitive element configuration. It was shown that at least three technological operations are excluded at laser vaporization as compared with photolithography method. Research results on the formation of topologies with the usage of laser processing are presented. We have determined the parameters of laser processing for sensor topology configuring by means of thin-film coating evaporation with a thickness of 400 nm, which comprises 350 nm of aluminum and 50 nm of vanadium adhesive coating applied on a substrate made of quartz. The amplitude-frequency characteristic of the manufactured sample is obtained. It is revealed that the experimental sample has a high loss value caused by inaccuracies in its manufacturing technology. Recommendations were worked out for minimization of error sources in the manufacturing technology of microgyroscope sensitive element on surface acoustic waves with the use of the laser configuration method

Integrated optics technology study

The materials and processes available for the fabrication of single mode integrated electrooptical components are described. Issues included in the study are: (1) host material and orientation, (2) waveguide formation, (3) optical loss mechanisms, (4) wavelength selection, (5) polarization effects and control, (6) laser to integrated optics coupling,(7) fiber optic waveguides to integrated optics coupling, (8) souces, (9) detectors. The best materials, technology and processes for fabrication of integrated optical components for communications and fiber gyro applications are recommended

Laser light induced domain engineering of lithium niobate for photonic and phononic applications

This thesis presents novel domain engineering techniques in lithium niobate (LiNbO3) crystals by using focused laser light irradiation to path the way to sub-micron domain periods for applications in the field of photonics and phononics. A new technique for tailoring of ferroelectric surface domains is introduced on the non-polar cuts of LiNbO3 by scanning a focused ultraviolet (UV) laser beam (λ = 244 nm) across the surface, using a scheme of writing and partially erasing the previously written domains. Domain periods down to 4 μm are realised, where the domain depth profile is 'half-crescent-shaped'. Reduction of laser induced surface damage is achieved by coating the LiNbO3 crystal surface with a Cr layer, thereby combining the direct laser writing technique with a diffusion process to accomplish domain inversion. Bulk domain patterns with a period of down to 3 μm are obtained in MgO-doped LiNbO3 crystals by combining laser induced poling inhibition with a sequence of electric field poling steps. The uniformity of the bulk domains is confirmed by nonlinear optical conversion of laser light with a wavelength of 1550 nm into 775 nm . Sub-micron surface domain patterns are achieved by patterned Cr and visible laser light irradiation (λ = 532 nm). This allows for the generation of 2D poling patterns with periods down to 100 nm. Finally, direct laser written domain patterns are used to excite surface acoustic waves to drive flow and suspended microparticles within a fluid droplet. This demonstrates that the platform can be exploited for practical microfluidic manipulation

Integrated sensors for process monitoring and health monitoring in microsystems

This thesis presents the development of integrated sensors for health monitoring in Microsystems, which is an emerging method for early diagnostics of status or “health” of electronic systems and devices under operation based on embedded tests. Thin film meander temperature sensors have been designed with a minimum footprint of 240 m × 250 m. A microsensor array has been used successfully for accurate temperature monitoring of laser assisted polymer bonding for MEMS packaging. Using a frame-shaped beam, the temperature at centre of bottom substrate was obtained to be ~50 ºC lower than that obtained using a top-hat beam. This is highly beneficial for packaging of temperature sensitive MEMS devices. Polymer based surface acoustic wave humidity sensors were designed and successfully fabricated on 128° cut lithium niobate substrates. Based on reflection signals, a sensitivity of 0.26 dB/RH% was achieved between 8.6 %RH and 90.6 %RH. Fabricated piezoresistive pressure sensors have also been hybrid integrated and electrically contacted using a wire bonding method. Integrated sensors based on both LiNbO3 and ZnO/Si substrates are proposed. Integrated sensors were successfully fabricated on a LiNbO3 substrate with a footprint of 13 mm × 12 mm, having multi monitoring functions for simultaneous temperature, measurement of humidity and pressure in the health monitoring applications

Enhanced Piezoelectric Performance of Printed PZT Films on Low Temperature Substrates

Since piezoelectric effect was discovered in 1880, it has been widely used in micro-actuators, sensors, and energy harvesters. Lead Zirconate Titanate (PZT) is a commonly used piezoelectric material due to the high piezoelectric response. The basic PZT film fabrication process includes deposition, sintering, and poling. However, due to the high sintering temperature (\u3e 800 °C) of PZT, only high melting point material can be served as the substrate. Otherwise, complex film transfer approach is needed to achieve flexible and foldable PZT devices. The exploration is accordingly necessary to realize direct fabrication of PZT films on low melting point substrates without affecting the piezoelectric performance. In order to lower the PZT film sintering temperature, in this work, the effect of the powder size and sintering aid on the sintering temperature was studied. A maskless, CAD driven, non-contact direct printing system, aerosol jet printer, was used to deposit PZT thick films on the substrate. This technique allows creating features without masking and etching processes that are generally required for realizing designed features via conventional deposition approaches. Broadband, sub-millisecond, high intensity flash pulses were used to sinter the PZT films. The role of all sintering parameters was investigated to regulate the sintering quality of the PZT thick films. The photonically sintered films showed much lower substrate temperature increase mainly due to the extremely short pulse duration and temperature gradient through the film thickness. The superior piezoelectric property to thermally sintered group was also obtained. This process significantly shortens the processing duration and dramatically expands the possible substrate materials. It accordingly opens the possibility of processing PZT film directly on low melting point materials. A PZT energy harvester based on this process was directly fabricated on the polyethylene terephthalate (PET) substrate to demonstrate the capability. The relation between the load and the generated power was investigated to obtain the highest output power. Up to 0.1 μW was generated from this flexible energy harvester when connected with 10 MΩ resistive load. Photonic sintering of PZT film also creates the opportunity of processing poling during sintering. Different combinations of the sintering and poling techniques were studied. It was observed that the best piezoelectric property was obtained while performing poling during photonic sintering. Consequently, a new method of printing, sintering, and poling of micro-scaled PZT films was demonstrated in this work resulting in high performance films. This process provides the capability of realizing PZT devices on low temperature substrate, facilitates the fabrication of flexible piezoelectric devices, and enhances the piezoelectric property

Microelectromechanical Systems and Devices

The advances of microelectromechanical systems (MEMS) and devices have been instrumental in the demonstration of new devices and applications, and even in the creation of new fields of research and development: bioMEMS, actuators, microfluidic devices, RF and optical MEMS. Experience indicates a need for MEMS book covering these materials as well as the most important process steps in bulk micro-machining and modeling. We are very pleased to present this book that contains 18 chapters, written by the experts in the field of MEMS. These chapters are groups into four broad sections of BioMEMS Devices, MEMS characterization and micromachining, RF and Optical MEMS, and MEMS based Actuators. The book starts with the emerging field of bioMEMS, including MEMS coil for retinal prostheses, DNA extraction by micro/bio-fluidics devices and acoustic biosensors. MEMS characterization, micromachining, macromodels, RF and Optical MEMS switches are discussed in next sections. The book concludes with the emphasis on MEMS based actuators

EUROSENSORS XVII : book of abstracts

Fundação Calouste Gulbenkien (FCG).Fundação para a Ciência e a Tecnologia (FCT)

Dispositivos de ondas acústicas de superfície com base em filmes de nitreto de alumínio depositados por processos a plasma

The study of thin films of aluminum nitride (AlN) and devices constructed involving surface acoustic waves (SAW) technology is complex. However, this work serves as a basis for the development of SAW devices, such as filters with high selectivity, resonators, identification tags, delay lines, pulse compressors, different sensors (pressure, temperature, biosensors). Devices constructed on AlN films use wireless technology and are capable of operation in harsh environments without suffering degradation. The activity took place on four fronts: the first one refers to the synthesis of AlN thin films, and aimed at the establishment of criteria to characterize the deposition of AlN films by reactive RF magnetron sputtering; the second concerns the application of the techniques of analysis by X-ray diffraction (XRD), infra-red spectroscopy with Fourier transform (FTIR), Raman spectroscopy, profilometry and spectroscopy by Rutherford backscattering (RBS); the third front refers to the project of new SAW devices and Photolithography; the fourth is the acoustic characterization using a network Analyzer, and aimed at the determination of the SAW velocity, electromechanical coupling coefficient and frequency response of the devices. This work performed a study of the main problems involved in the deposition of aluminum nitride films, with good texturing AlN (100), and highly crystalline. It was studied the influence of the high SAW velocity of AlN films on the manufacture of SAW devices. The main characteristic parameters of the SAW devices performance, manufactured in the delay line configuration, were analyzed. It was suggested a new method of estimation of SAW speed based on the impulse response of the devices constructed. Hence this new method is more extensive than those found in the scientific literature. The results of the analysis of AlN films are consistent with those found in specialized literature. It was possible to construct SAW devices based on the AlN(100)/Si(100) structure. The SAW devices showed a satisfactory response in the frequency domain and their characteristic parameters were determined.Agência 1O estudo dos filmes finos de nitreto de alumínio (AlN) e dos dispositivos construídos envolvendo a tecnologia de ondas acústicas de superfície (OAS) é complexo. Contudo, este trabalho serve de base no desenvolvimento de dispositivos SAW, tais como filtros com alta seletividade, ressonadores, etiquetas de identificação, linhas de retardo, compressores de pulsos, sensores diversos (pressão, temperatura, biosensores). Os dispositivos construídos sobre filmes de AlN usam a tecnologia sem fio e são capazes de operar em ambientes agressivos sem sofrerem degradação. A atividade se deu em quatro frentes: a primeira refere-se à síntese de filmes finos AlN, e visou ao estabelecimento de critérios a fim de caracterizar a deposição dos filmes AlN por pulverização reativa com magnetron e RF; a segunda diz respeito à aplicação das técnicas de análise por difração de raios-X (XRD), espectroscopia por infravermelho com transformada de Fourier (FTIR), espectroscopia Raman, perfilometria e espectroscopia por espalhamento Rutherford (RBS); a terceira refere-se ao projeto de novos dispositivos SAW e fotolitografia; a quarta trata-se da caracterização acústica usando um analisador de rede, e visou-se a determinação da velocidade da SAW, coeficiente de acoplamento eletromecânico e resposta em frequência dos dispositivos. Neste trabalho, realizou-se um estudo dos principais problemas envolvidos na deposição dos filmes de nitreto de alumínio, com boa texturização AlN(100), e altamente cristalinos. Estudou-se a influência da alta velocidade SAW desses filmes de AlN sobre a confecção dos dispositivos SAW. Os principais parâmetros característicos do comportamento dos dispositivos SAW, fabricados na configuração de linha de retardo, foram analisados. Sugeriu-se um novo método de estimativa da velocidade SAW com base na resposta ao impulso dos dispositivos construídos. Donde esse novo método é mais abrangente que os encontrados na literatura científica. Os resultados das análises dos filmes AlN são coerentes com os encontrados na literatura especializada. Foi possível construir dispositivos SAW com base na estrutura AlN(100)/Si(100). Os dispositivos SAW mostraram uma resposta no domínio da frequência satisfatória e seus parâmetros característicos foram determinados