SAW synchronous multimode resonator with gold electrodes on quartz

A surface acoustic wave synchronous multimode resonator with gold electrodes on ST-cut quartz was designed, fabricated, and measured. At a frequency of about 194.3 MHz, an insertion loss of about 14 dB, and loaded and unloaded quality factors of 11,500 and 14,500, respectively, were obtained.     

Scattering matrix approach to STW resonators

The scattering matrix method was used for the analysis of surface transverse wave (STW) resonators on quartz. An expression for the transfer function of the resonators with different numbers of electrodes in the reflectors was derived. It was found that, for a proper ratio of these numbers, the spurious signal level below the resonance frequency can be lowered. The STW resonator for the frequency near 1090 MHz was designed, fabricated, and measured. By matching the measured and calculated transfer functions, the velocity, the electromechanical coupling coefficient, and the reflection coefficient of one aluminium strip of the STW on the 36°Y-cut quartz were determined. The insertion loss about 7 dB, loaded quality coefficient near 4200, and the spurious signal level about 5 dB lower compared with the resonance one were obtained for the resonator     

STW in-line acoustically coupled resonator filter on quartz

The scattering-matrix method was used for design of a surface transverse wave (STW) in-line acoustically coupled resonator filter on quartz. In this filter, two one-port STW resonators were coupled by means of a center reflector, grating phase shifters were placed between interdigital transducers and reflectors, and the pass band of the filter was located near the center frequency of the reflectors. At a frequency of about 509 MHz, insertion loss of about 5 dB and a 3 dB bandwidth of about 0.23 MHz was obtained. Differences between the measured and calculated amplitude responses are explained and design guidelines are presented. High STW velocity, low insertion loss, and very weak transverse mode make this filter attractive for high-frequency applications.     

Properties of SAW synchronous two-port resonators on GdCa₄O(BO₃)₃ crystal

Surface acoustic wave (SAW) synchronous two-port resonators were fabricated and measured on several orientations of the GdCa?O(BO?)? crystal. Resonance frequencies, insertion losses, and unloaded quality factors of the resonators, measured at room temperature, were in the ranges of about 432.3 to 437.5 MHz, 3.8 to 6.3 dB, and 6500 to 7500, respectively. The properties of this crystal, such as its lack of a phase transition up to its melting temperature of about 1500 °C, a SAW temperature coefficient of frequency of about -80 ppm/ °C, and good parameters of the resonators make the crystal attractive for high-temperature sensor applications.     

Athermal arrayed waveguide gratings in silicon-on-insulator by overlaying a polymer cladding on narrowed arrayed waveguides

Athermal arrayed waveguide gratings (AWGs) in silicon-on-insulator (SOI) are experimentally demonstrated for the first time to our knowledge. By using narrowed arrayed waveguides, and then overlaying a polymer layer, the wavelength temperature dependence of the AWGs is successfully reduced to -1.5 pm/°C, which is more than 1 order of magnitude less than that of normal SOI AWGs. The athermal behavior of the AWGs is obtained with little degradation of their performance. For the central channel, the cross talk is less than -15 dB and the insertion loss is around 2.6 dB. Good characteristics can be maintained with temperatures up to 75 °C. The total size of the device is 350 μm × 250 μm.     

Attenuation of acoustic normal modes in piezoelectric plates loaded by viscous liquids

Attenuation cac versus viscosity eta of adjacent liquid is measured for each normal mode n generated in 30 different plates of commercially available, piezoelectric crystals with thickness-to-wavelength ratio in the range h/lamda = 0.6 - 2.5. Two modes with an optimal combination of sensitivity (0.1 dB/mm x cP), insertion loss (<35 dB), and stop-band rejection (>15 dB) are found in liquid-loaded 128 degrees Y,X + 90 degrees - LiNbO3 with h/lamda = 1.67. Both modes are suited for viscosity measurements and other sensing tasks in viscous liquids. They have predominantly longitudinal displacement and large propagation velocity v(n), about 15,000 m/s.     

Poloxamer 407 as a Thermogelling and Adhesive Polymer for Rectal Administration of Short-Chain Fatty Acids

Objectives: The purpose of the study was to gel a rectal solution of short-chain fatty acids to decrease the loss of active materials in the colonic lumen and thereby optimize their absorption. Methods: Five thermogels were prepared with poloxamer 407 at concentrations ranging from 17% to 20%. Their viscosities were measured at room temperature and 37°C, and their gelling temperatures were determined. The adhesive properties of each gel were assessed in vitro at 37°C. Short-chain fatty acid release was studied using Guyot cells. Results: From the threshold concentration of 17.5%, the solutions, Newtonian at room temperature (50-80 mPa · s), gelled at 37°C. The higher the concentration, the higher the viscosity (1750 to 49,000 mPa · s), the lower the gelling temperature (27.6°C to 23.4°C), and the stronger the work of adhesion (2.2 to 4.5 mJ). Short-chain fatty acid release from the 18% polymer gel was decreased by 60% compared to the rectal solution. Conclusion: The 18% poloxamer 407 concentration provided a solution that was liquid at room temperature, that gelled at 37°C, possessed adhesive properties, and controlled short-chain fatty acid release.     

Surface acoustic wave two resonator filter using synchronous coupling interdigital transducers

A surface acoustic wave (SAW) two resonator filter with coupling interdigital transducers (IDTs) located inside the reflectors, was designed, fabricated, and tested. In the filter, electrodes of the coupling IDTs are in spatial synchronism with the reflectors' electrodes. The filter, fabricated on ST-cut quartz, had a center frequency of 302.6 MHz, insertion loss about 13 dB, and minimum rejection in the stopbands of about 40 dB.     

Determination of the physical properties of room temperature ionic liquids using a Love wave device

In this work, we have shown that a 100 MHz Love wave device can be used to determine whether room temperature ionic liquids (RTILs) are Newtonian fluids and have developed a technique that allows the determination of the density-viscosity product, ρη, of a Newtonian RTIL. In addition, a test for a Newtonian response was established by relating the phase change to insertion loss change. Five concentrations of a water-miscible RTIL and seven pure RTILs were measured. The changes in phase and insertion loss were found to vary linearly with the square root of the density-viscosity product for values up to (ρη)(1/2) ~ 10 kg m(-2) s(-1/2). The square root of the density-viscosity product was deduced from the changes in either phase or insertion loss using glycerol as a calibration liquid. In both cases, the deduced values of ρη agree well with those measured using viscosity and density meters. Miniaturization of the device, beyond that achievable with the lower-frequency quartz crystal microbalance approach, to measure smaller volumes is possible. The ability to fabricate Love wave and other surface acoustic wave sensors using planar metallization technologies gives potential for future integration into lab-on-a-chip analytical systems for characterizing ionic liquids.     

Comparative analysis of viscosity of complex liquids and cytoplasm of mammalian cells at the nanoscale

We present a scaling formula for size-dependent viscosity coefficients for proteins, polymers, and fluorescent dyes diffusing in complex liquids. The formula was used to analyze the mobilities of probes of different sizes in HeLa and Swiss 3T3 mammalian cells. This analysis unveils in the cytoplasm two length scales: (i) the correlation length ξ (approximately 5 nm in HeLa and 7 nm in Swiss 3T3 cells) and (ii) the limiting length scale that marks the crossover between nano- and macroscale viscosity (approximately 86 nm in HeLa and 30 nm in Swiss 3T3 cells). During motion, probes smaller than ξ experienced matrix viscosity: η(matrix) ≈ 2.0 mPa·s for HeLa and 0.88 mPa·s for Swiss 3T3 cells. Probes much larger than the limiting length scale experienced macroscopic viscosity, η(macro) ≈ 4.4 × 10(-2) and 2.4 × 10(-2) Pa·s for HeLa and Swiss 3T3 cells, respectively. Our results are persistent for the lengths scales from 0.14 nm to a few hundred nanometers.     

Athermalized low-loss echelle-grating-based multimode dense wavelength division demultiplexer

A high-density wavelength division demultiplexer (DEMUX) capable of demultiplexing eight-channel 200-GHz optically spaced signals into a 62.5-microm multimode-fiber array is reported. The wavelength range of operation is from 1549.32 to 1560.61 nm within the International Telecommunication Union grid. The measured wavelength accuracy is within 0.04 nm. The mean insertion loss of this DEMUX is 1.95 dB. Thermal analysis and temperature testing results are reported. The temperature test cycling from 20 degrees C to 60 degrees C indicates that the wavelength thermal drift is less than 0.8 pm/degrees C. Adjacent cross talk is measured to be better than -45 dB. The measured data transmission bit rate of this device is higher than 3.5 Gb/s.     

疏水缔合羟乙基纤维素水溶液的流变性及驱油性能

研究了疏水缔合改性羟乙基纤维素(BHEC)水溶液的流变性和驱油性能。结果表明,BHEC的临界缔合浓度在4000 mg/L左右,其增粘性能是HEC的近22倍;NaCl对BHEC水溶液有促进作用,当NaCl含量达到100000 mg/L时,BHEC的表观黏度仍然稳定在699.9 mPa.s,说明其具有良好的抗盐性。BHEC水溶液达到临界缔合浓度才具有粘弹性,并随着聚合物浓度的增加,聚合物溶液的粘弹性越显著,振荡频率越高,损耗因子越低。浓度为6000 mg/L的BHEC水溶液可在水驱基础上提高原油采收率25%~32%。     

Poloxamer 407 as a Thermogelling and Adhesive Polymer for Rectal Administration of Short-Chain Fatty Acids

Objectives: The purpose of the study was to gel a rectal solution of short-chain fatty acids to decrease the loss of active materials in the colonic lumen and thereby optimize their absorption. Methods: Five thermogels were prepared with poloxamer 407 at concentrations ranging from 17% to 20%. Their viscosities were measured at room temperature and 37°C, and their gelling temperatures were determined. The adhesive properties of each gel were assessed in vitro at 37°C. Short-chain fatty acid release was studied using Guyot cells. Results: From the threshold concentration of 17.5%, the solutions, Newtonian at room temperature (50–80 mPa · s), gelled at 37°C. The higher the concentration, the higher the viscosity (1750 to 49,000 mPa · s), the lower the gelling temperature (27.6°C to 23.4°C), and the stronger the work of adhesion (2.2 to 4.5 mJ). Short-chain fatty acid release from the 18% polymer gel was decreased by 60% compared to the rectal solution. Conclusion: The 18% poloxamer 407 concentration provided a solution that was liquid at room temperature, that gelled at 37°C, possessed adhesive properties, and controlled short-chain fatty acid release.     

Small and low-loss IF SAW filters using zinc oxide film on quartz substrate

It was previously reported that a Rayleigh wave propagating on a zinc oxide film (ZnO)/ST-cut 35 degrees X propagation quartz substrate structure has the characteristics of an excellent temperature coefficient of frequency (TCF) and a large electromechanical coupling factor k(s). This substrate was applied to various intermediate-frequency (IF) stage filters. During the filter development, it was clarified that a spurious response due to the Love wave was generated. In this study, a new quartz substrate has been developed with a specific cut and propagation angle, that has the same values of the TCF and the coupling factor as the above-mentioned ones. In addition, it does not have the spurious response due to the Love wave. The combination of this specific-cut-angle quartz and ZnO film has been applied to IF filters for wideband code division multiple access (W-CDMA) and narrow-band CDMA (N-CDMA) systems. The insertion losses of their IF filters were 3-5 dB better and their TCF was superior (deltaf/f = 0.37 ppm/degrees C: one-third) compared with the conventional surface acoustic wave (SAW) filters.     

A multi-degree of freedom acoustic lining for noise suppression in broad air ducts

A combination multi-degree of freedom acoustic lining is designed. A given space volume (30 × 37 × 1000 cm³) is properly distributed in different levels. As a result 28-acoustic resonators of the Helmholtz type and two similar triangular chambers are obtained. These resonators are tuned to different frequencies, so that they cover a frequency range from 65 Hz to about 450 Hz. The measured third octave band insertion loss showed a wide band attenuation in the frequency range from 80 Hz to about 600 Hz. When the triangular chambers are filled with loose fibre (jute) as absorbent material, the attenuation of the lining extends to higher frequencies, up to about 2000 Hz. An average insertion loss of more than 20 dB is measured in a wide frequency range.     

Pressure Dependence of Bis(2-ethylhexyl) Sebacate and VG32 Hydraulic Oil Viscosities Using a Quartz Crystal Resonator

Conductances versus sweep frequencies for AT-cut quartz crystal resonators have been measured for bis(2-ethylhexyl) sebacate and several machine oils under high pressure. The frequencies versus viscosities of these liquids appeared on the correlation line between frequency shift and viscosity. The correlation line agreement is essentially a criterion for when quartz resonators may be used because non-Newtonian silicone oils deviated from the correlation line. The responses of resonators immersed in bis(2-ethylhexyl) sebacate were obtained at pressures up to 350 MPa. Viscosities were calculated from the resonance frequencies. The pressure dependence of the bis(2-ethylhexyl) sebacate viscosity agreed well with that obtained with the rolling ball method. By using reference liquids, it was found that resonator responses were independent of temperature over the range 295–372 K. Viscosity measurements for VG32 hydraulic oil were taken at pressures up to 250 MPa and at the temperature at which the commercial viscosity grade was defined [313 K (40 °C)].     

Fabrication of high frequency spherically shaped ceramictransducers

Difficulty in obtaining well focused efficient ultrasound transducers has limited the development of new high frequency applications of B-mode imaging. This paper describes a method for fabricating high frequency (53 MHz) spherically focused lead zirconate titanate (PZT) transducers. A transducer is fabricated by bonding a malleable backing layer onto a thin plate of PZT and then pressing the plate into a spherically shaped well. The backing layer evenly distributes stresses across the material when it is pressed into the well. Local concentrations of stress which lead to fracture are avoided and the material can be deformed without macroscopic cracking. The characteristics of a 2 mm diameter 53 MHz PZT transducer with a 4 mm focal length are described. A lateral beam width of 68 μm and a 12 dB depth of field of 1.5 mm were obtained. The minimum two-way insertion loss of the system was -25 dB and the 6 dB bandwidth of the pulse echo response was 30%. An image of a resolution phantom and an in vivo skin image illustrate the excellent imaging characteristics of the transducer     

Super high electromechanical coupling and zero temperature coefficient surface acoustic wave substrates in KNbO(3) single crystal

The propagation characteristics of surface acoustic waves (SAW) and piezoelectric leaky surface waves in KNbO(3) single crystal have been investigated theoretically and experimentally. The results show that the electromechanical coupling coefficient k(2) of the surface wave propagating along the X-axis of the rotated Y-cut plate is very large with k(2)=0.53. This is about 10 times as large as that of LiNbO(3) in the surface wave branch. Experimental results for wideband SAW filters show low loss and temperature stable characteristics. The bandwidth is about 20%, and insertion losses are less than 2 to 6 dB. Simulation results for a ladder type filter using Y-cut KNbO(3) indicate that a bandwidth of 40% should be possible. The KNbO(3) substrates exhibit zero temperature coefficient of frequency (TCF) around 20 degrees C in rotated Y-cut substrates.     

Planar LiTaO(3) waveguides fabricated by proton exchange in concentrated and diluted pyrophosphoric acid with annealing

Annealed proton-exchanged z-cut LiTaO(3) planar waveguides fabricated with pyrophosphoric acid have been characterized. For proton exchange, the extraordinary index increase Δ n(e) ranged from 0.0119 to 0.0141, depending on the exchange temperature. The effective diffusion coefficient D(e) ranged from 0.1325 μm(2)/h at 240°C to 0.545 μm(2)/h at 280 °C. Single-mode propagation losses were α = 0.7 dB/cm. Compared with benzoic acid, pyrophosphoric acid produces waveguides with a higher Δ n(e) and a lower propagation loss. For proton exchange in lithium phosphate-diluted pyrophosphoric acid, a lower Δ n(e) was obtained, but D(e) and propagation losses were not reduced. After proton exchange, the waveguides were annealed. The surface index initially increased, peaked, and then decreased. The waveguide depth d and the surface index n(s) were measured at regular intervals. Figures and empirical formulas relating the waveguide depth d and the surface index increase Δ n(s) to the anneal time, anneal temperatures, and the waveguide depth after proton exchange are given. An example is given in which, the desired waveguide parameters d and Δ n(s), the fabrication conditions could be calculated with the previously derived formulas. Propagation losses decreased to 0.4 dB/cm after prolonged annealing.     

LED封装用液体交联剂的制备与表征

报道了一种功率型发光二极管(LED)封装用液体高分子交联剂的制备方法。将甲基氢环硅氧烷与八甲基环四硅氧烷、甲基苯基混合环体等环硅氧烷,在甲苯溶剂中,40℃~80℃,用阳离子交换树脂催化其开环共聚,并以适量四甲基二氢硅氧烷封端。产物为澄清透明的甲基苯基含氢硅油,其苯基含量(Ph/Si,molar ratio)为0.30~0.60,活泼氢(Si-H)含量为0~0.5%,折光指数为1.39~1.51(25℃),动力黏度为100 mPa.s~550 mPa.s(25℃)。