Xiu-ji Shui

Experimental study of Love-wave immunosensors based on ZnO/LiTaO3 structures

Experimental study of Love-mode immunosensors based on structures of ZnO/36 degrees YX-LiTaO3 is presented, in which the ZnO films with c-axis (002) orientation have been successfully grown on the 36 degrees YX-LiTaO3 substrates by RF magnetron sputtering technique. Then the Love-mode immunosensors based on the ZnO/36 degrees YX-LiTaO3 structures and monitoring antibody-antigen immunoreactions in aqueous solutions in real time are fabricated. The experimental results show that the optimal thickness of ZnO layers is about 1.20 microm in the structures deposited on 36 degrees YX-LiTaO3 substrates, which is much less than that of SiO2 overlayers about 6 microm. The antibody-antigen immunoreaction experiments also show that the frequency shifts of the sensors with 1.33 microm ZnO films are proportional to the concentration of antigen in solution as the concentration range less than 100 microg/ml.

Miniaturization of surface acoustic waves rotary motor

This paper presents the experimental study of a miniaturized surface acoustic waves (SAWs) rotary motor and the theoretical calculation. After the first success in SAW rotary motor operating at 9.85 MHz, a smaller rotary motor is designed. With the operating frequency of 30 MHz and the driving voltage of 120 V(p-p), the motor can rotate at a speed of 270 rpm.

Characteristics of surface acoustic waves excited by (1120) zno films deposited on R-sapphire substrates

(112̅0)-textured ZnO films are deposited on Rsapphire substrate by RF magnetron sputtering and the effects of deposition conditions on ZnO films are investigated. The chemical compositions of the ZnO films are characterized by X-ray photoelectron spectroscopy and the results indicate that the ratio of latticed oxygen to zinc increases with increasing of oxygen concentration in the sputtering gas, which demonstrates the improvement of crystal structures in ZnO films. To investigate the characteristics of surface acoustic waves excited by the (112̅0)-textured ZnO films, SAW delay lines based on layered structures of (112̅0) ZnO film/R-sapphire substrate are fabricated, in which Rayleigh and Love modes are excited along the (0001)- and (11̅00)-directions of the ZnO films, respectively. The phase velocities and electromechanical coupling factors of both wave modes are characterized as functions of the film-thickness-to-wavelength ratio. The acoustic properties of the layered structures are calculated using the transfer matrix method. The experimental and theoretical results are in good agreement with each other.

Surface Acoustic Wave Humidity Sensors Based on

ZnO films on R-sapphire substrates are prepared and characterized by x-ray diffraction and scanning electron microscopy, which indicate that the thin films are well crystallized with texture. Love wave and Rayleigh wave are used for fabrications of humidity sensors, which are excited in and [0001] directions of the ZnO piezoelectric films, respectively. The experimental results show that both kinds of sensors have good humidity response and repeatability, and the performances of the Love wave sensors are better than those of the Rayleigh wave sensors at room temperature. Moreover, the theoretical calculations of the mass sensitivity of the sensors are also carried out and the calculated results are in good agreement with the experimental measurements.

(11\bar{2}0)

Love-wave immunosensors based on SiO2/36°YX-LiTaO3 or ZnO/36°YX-LiTaO3 structures coated by special sensitive films have been fabricated and studied experimentally. A theoretical model using the partial wave theory of elastic waves propagating in three-layer structures covered by liquid loads is built up to calculate the sensitivities. To determine the elastic constants of the guiding layers, the phase velocities of the corresponding Love-wave devices are measured by a network analyzer, and the theoretical fitting of the experimental data are carried out. Then the relationships between the sensitivities of the Love-wave immunosensors and normalized thicknesses of the guiding layers are obtained, and there are optimized thicknesses of the guiding layers for getting maximum sensitivities. The experimental measurements and numerical calculations of the sensitivities of the Love-wave immunosensors show that both results are essentially consistent with each other.

ZnO Piezoelectric Films Sputtered on R-Sapphire Substrates

The authors have proposed a kind of non-contact linear motors driven by SAWs, in which the fluid is introduced between the stator and the slider. As the SAWs are excited in the stators, the sliders will be driven by SAW streaming in linear motion. The experiments results show that the the slider displacement increases exponentially as time increase, at the same time, the slider velocity is proportional to the driving voltage, and decreases exponentially approximately with the thickness of the aqueous solution of glycerin increase.

Study on sensitivities of Love-wave immunosensors based on SiO2/36°YX-LiTaO3 and ZnO/36°YX-LiTaO3 structures

La-doped and undoped xBiInO3-(1 − x) PbTiO3 (BI-PT) thin films are deposited on (101)SrRuO3/(100)Pt/100) MgO substrates by the rf-magnetron sputtering method. The structures of the films are characterized by XRD and SEM, and the results indicate that the thin films are grown with mainly (100) oriented and columnar structures. The ferroelectricity and piezoelectricity of the BI-PT films are also measured, and the measured results illustrate that both performances are effectively improved by the La-doping with suitable concentrations. These results will open up wide potential applications of the films in electronic devices.

Experimental study on non-contact linear motors driven by surface acoustic waves

The (110) textured ZnO films with c-axes lying in R-sapphire substrate planes are deposited by RF magnetron sputtering. The focusing investigation is the effect of substrate position in the sputtering on structural and acoustic properties of the ZnO films on the sapphire. The crystallographic characteristics of the films are characterized by X-ray diffraction (XRD) analysis. It is found that the crystalline orientation of the ZnO film varies with the substrate position deflected from the center of the target. The XRD spectra of the films show that there is an optimized substrate position, at which the strongest (110) peak of the ZnO film can be obtained. However, with the decrease or further increase of the deflection, the (110) diffraction intensity decreases and additional diffraction peaks of (002), (102) and (103) emerge. In order to investigate the variations of acoustic properties of these films, the ZnO piezoelectric films are deposited on R-sapphire substrates with different deflection positions, ...

Characterization of La-doped xBiInO3(1 − x)PbTiO3 Piezoelectric Films Deposited by the Radio-Frequency Magnetron Sputtering Method*

An infrared thermography is used for non-contact characterisations of thermal properties of materials. In the experiment, a pulsed laser is used to excite a transient thermal source in the material, and an infrared camera system is used to record the infrared thermal images of the subsequent heat diffusion and heat loss processes. In the theory, by a solving heat conduction equation, a two-dimensional thermal distribution function produced by the pulsed laser excitation can be obtained. Then, based on the relations between both the two-dimensional thermal distribution functions extracted at any two times, the thermal diffusivities and heat loss rates of the materials can be obtained by fitting the theoretical calculations to the infrared images recorded at different times. The results indicate that this method is useful to determine the thermal diffusivity and thermal loss for industrial non-metallic materials with rough surfaces and/or inhomogeneous microstructures.

Deposition of ZnO films with c-axes lying in R-sapphire substrate planes

Photothermal (PT) effect has been applied to manufacture disks [A. C. Tam, a lecture at the Institute of Acoustics, Nanjing University, People’s Republic of China (1996)] and magnetic head sliders for disk drives [A. C. Tam, C. C. Poon, and L. Crawforth, Analyt. Sci. 17, s 419 (2001)]. Now we apply the PT effect to manufacture ultrasonic motors (actuators). Recently, the ultrasonic actuators with different ultrasonic modes, such as Rayleigh (surface acoustic) mode, Lamb (plate) mode, etc., have been developed. We have designed and fabricated two rotary motors driven by surface acoustic wave (SAW) with different frequencies, but lower than 30 MHz [L. P. Cheng, G. M. Zhang, S. Y. Zhang, J. Yu, and X. J. Shui, Ultrasonics 39, 591 (2002)]. On the SAW motors (actuators), two Rayleigh wave beams were generated and propagating along the surface of a 128° YK-LiNbO3 substrate in opposite directions with each other as a stator, and a plastic disk with balls distributed along the circle of the disk was as a rotor. F...