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In this paper, we describe a 920 MHz band long range wireless SAW passive tag system (WSPTS) for vibration monitoring, which achieves more than 10m reading distance. For the purpose of structural health monitoring (SHM) of aging infrastructures (e.g. bridge, building, and so forth), passive wireless sensor systems are an attractive option because they are operated battery-less and almost maintenance...
Lithium (Li) has long been known to be the best anode material for rechargeable batteries, however, lithium metal batteries (LMB) have never been commercialized due to dendrite formation, resulting in thermal runaway and fire or explosion. During charging, Li ions deposit onto Li anode from the cathode via electrolyte. However, the deposition is not uniform due to the inhomogeneous ion distribution...
Suppression of the SH-SAW response is mandatory to design TC SAW devices on θ degree rotated Y-cut LiNbO3. However, it is not easy because K2 for SH SAW changes rapidly with θ, and its optimal value in terms of the SH-SAW suppression is dependent on electrode and SiO2 thicknesses. The authors found that the optimal θ always locates close to θ where difference in velocities of two SAWs is minimum....
Recently, contactless manipulation of immersed objects has garnered great interest. Specifically, acoustic manipulation in microfluidic channels has emerged as a tool to control micron-sized objects in chemical, medical, and biological applications. Pure and controllable acoustic forces of the acoustic manipulation method exhibit a minor negative impact on viability and functionality of biological...
Recently, it was shown that heavily doped AlN film possess the high piezoelectricity by Akiyama et al [1]. On the other hand, SAW devices were widely used as filters and sensors. Among them, SAW in ScAlN film is attracting a lot of attention because this SAW devices have high electromechanical coupling coefficient K2. We analyzed the K2 value in Sc0.4Al0.6N was increased by c-axis tilted angle θ becoming...
The growing complexity in RF front-ends, which support carrier aggregation and a growing number of frequency bands, leads to tightened nonlinearity requirements in all sub-components. The generation of third order intermodulation products (IMD3) are typical problems caused by the non-linearity of SAW devices. In the present work, we investigate temperature compensating (TC) SAW devices on Lithium...
Surface acoustic wave (SAW) devices are widely used as acoustic-electronic components today. The lithium niobate was often used as the substrate of SAW devices for its higher electromechanical coupling coefficient. In some applications like RFID tags and sensors, SAW devices have a long delay line and the energy loss of diffraction is considerable. Phononic crystals (PnC) have properties of band gaps...
The SAW on rotated “leaky” Y-cuts LiTaO3 and LiNbO3 is a dominantly localized near surface slow shear-horizontal wave, which is weakly coupled to the fast shear bulk wave. Any surface perturbation can lead to radiation of bulk-acoustic waves from the device, increasing losses. To minimize this radiation, LSAW resonators are typically synchronous, with all electrodes in the IDT and in the reflectors...
We previously demonstrated the potential of IrxRh1−x thin films (x < 0.5) as electrodes for high-temperature surface acoustic waves (SAW) applications [1]. To remind, we observed that after a 4-days annealing period at 800°C under air atmosphere, these films oxidize to form IrxRh1−xO2 films, which exhibit a resistivity suitable for the targeted application, especially as the Ir rate is high (ρ...
A grating structure serves as the most fundamental element of inter-digital transducers (IDTs). IDTs are used for excitation and detection of surface acoustic waves (SAW) in Ultra wide band (UWB) SAW devices. Reflections on the metal fingers greatly affect the functionality of IDTs, and thus that of the SAW devices they are used in. Hence, this effect has been studied extensively and several models...
Surface acoustic wave propagation in piezoelectric substrates is combined with nano-scale phenomena in sensing layer materials to realize practically viable chemical and biological sensors in our group. Ab initio electronic structure, molecular dynamics and finite element models are constructed to design these sensors and sensing materials, and understand sensing mechanisms at multiple length and...
Surface acoustic wave (SAW) devices are widely used as filters or resonators for mobile communications or radars applications. However, the velocity of the wave can be very sensitive to physical parameters of the environment (temperature, strain…), which allows the device to be used as a sensor. SAW devices are passive (batteryless) and wireless, but are often bulky due to the package. To dramatically...
Recently, a generation mechanism of nonlinear signals of SAW devices is one of the most important topics in the RF front-end field, because essential improvement of linearity is strongly demanded to SAW multiplexers to realize the uplink inter-band carrier aggregation.
In recent years, numerous SAW filters and duplexers are used in each mobile terminal. In such situations, miniaturization of SAW devices has been required and various efforts have been carried out. As for current SAW devices, most of the surface area of a SAW die is filled with interdigital transducers (IDTs). A size of IDTs highly depends on the wave length of the SAW, which is proportional to the...
The creating different kinds of the phononic crystals and acoustic metamaterials, which has advanced ultrasound properties, have generated considerable recent research interest. The new kind acoustic materials, allows to studying the new effects of the ultrasound interaction and developing different types of the surface acoustic wave (SAW) devices for electronic industry. We represented the possibilities...
We report on the fabrication, experimental characterization, and theoretical modeling of delay lines fabricated on a lithium niobate X-cut thin film substrate. We demonstrate the feasibility of fabricating delay lines on lithium niobate suspended thin films to take advantage of the high electromechanical coupling of Lamb waves in this material. Specifically, we design the delay lines with an orientation...
In the present work, nonlinearities in temperature compensating (TC) SAW devices are investigated. The materials used are LiNbO3-rot128YX as the substrate and Copper electrodes covered with a SiO2-layer as the compensating layer. In order to understand the role of these materials for the nonlinearities in such acoustic devices, a FEM simulation model in combination with a perturbation approach [1]...
ScAlN films are attractive for SAW devices with high electromechanical coupling coefficient K2. In previous study, we analyzed K2 in c-axis-tilted Sc0.4Al0.6N film / diamond substrate. The K2 of c-axis-tilted film was increased, compared with that of the c-axis-normally-oriented film. However, it is difficult to perform experiments because diamond substrate are very expensive. In this study, K2 of...
Small sized surface acoustic wave (SAW) devices with high performances have been strongly demanded. In order to fulfill these requirements, we have developed a small sized temperature compensated SAW (TC-SAW) duplexer. The die size of current SAW devices highly depends on the size of interdigital transducers (IDTs) which is proportional to the acoustic velocity of the SAW. Therefore, we tried to lower...
Surface acoustic wave gyroscopes are a solution for inertial navigation applications which require operability through high levels of shock and vibration. Integration of multiple axis gyroscopes in a small device are also needed to reduce the size and weight of the sensor system. Here we present a two-axis SAW gyroscope using bulk excited surface wave through the Lithium Niobate wafer. For the bulk...
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