Micro-Nano Technology XVII–XVIII

The following sections are included:

• Preface
• Contents

In this paper, an actively directed microfluidic cooling approach is introduced for thermal management of high power devices. The microfluidic cooler contains flow channels and an array of micron-scale impingement jets. The coolant can be actively delivered through the jets array and guided directly to the base of the heat source, significantly decreasing thermal resistance and increasing heat transfer coefficient. Finite element method has been used to investigate the effect of cooler module. Simulation results show that a 20W heat dissipation device with 2×2 mm² in size can be kept at 127°C by 20mL/min pumping rate. The average effective heat transfer coefficient with respect to a 20°C coolant temperature is around 13 W/cm² K. The actively directed microfluidic cooler is applicable to most of the current high power devices, such as GaN/SiC and GaN/Diamond power amplifiers. The approach is capable of managing die-level heat fluxes >1 kW/cm² very efficiently, enabling a die to operate at up to 2 times the power level as compared to the conventionally microfluidic cooled die for the same working temperature. Experiments verification of this high performance cooling system is currently underway at NEDI.

In order to develop a micro-force sensor with a high sensitivity, simple structure and low cost, a photoelastic SU-8 micro-force sensor is proposed in this paper. To improve the measurement sensitivity, a stress concentration area with flexible hinge shape is designed as the measurement region of the micro-force sensor. The measurement optical path of the SU-8 micro-force sensor is designed based on the photoelastic principle. A simple process with a UV-lithography process and a release process is used to fabricate the designed sensor. According to the experiment results, the sensor resolution is 51.44 nN ∼ 3.29 μN and the repeatability error is ∼7.47%. With the single-layer simple structure and good biocompatibility, the micro-force sensor has a good application prospect.

High-aspect-ratio silicon nitride waveguide with the characteristics of ultra-low loss and high polarization extinction ratio has the benefit to reduce the random walk coefficient (RWC) caused by photon shot noise and the polarization noise of the resonator integrated optic gyro. The splitting ratio is optimized by analysed its relation to the RWC and the propagation loss. Processing errors of the feature parameters which can affect the splitting ratio is given according to the Eigen Mode Expansion (EME) simulation. Based on the analysis, silicon nitride waveguide ring resonator whose feature parameters meets the design requirements is fabricated.

In this study, we investigated the self-polymerization of dopamine in alkaline solution to form the composite of polydopamine (PDA)/Ag and Ag nanoparticles (NPs) array. We use the reduction properties of PDA to change silver ions into silver NPs. We also use the adhesion properties of PDA to provide a new method to attach Ag NPs or put Ag NPs array on substrates. These NPs and array are a powerful platform for further functionalization, such as the electro-optic application field.

To fix the problem of low rate target recognition in single image and gigantic operation data in the fusing procedure, a method that combines Bayesian Compressive Sensing (BCS) with modified blocking and fusing criterion has been proposed in this paper. Aiming at retaining the performance of reconstruction and reducing data operation in the target recognition procedure, the image was segmented into tiny blocks by mean square error (MSE) of pixel. The blocks were separated into three types, namely: edge block, wave block and flat block. The information of infrared image is kept when the MSE is higher than a certain threshold, and information of visible and infrared were both kept when the MSE is lower than the threshold. The result of experiment shows that the modified method has better performance than the-state-of-art algorithms.

In order to meet the challenge of modern war, the fuze with S&A device inside worked as “the brain” of ammunition should be capable of miniaturization, intelligent and facility. It is very necessary to evaluate the reliability of the system. Nonlinear simulation method is generally used to calculate the reliability of a number of micro structures respectively to save cost for real manufacturing and test, but it takes a long time. Therefore, effectively simplifying and precisely simulating model become significant. In this paper, we present a simplified method based on the equivalent theory, theoretical analysis of the method to analyze the simulation model of the latching reed in the MEMS S&A device under high overload. Through the result, the calculation error of 0.02% between theoretical calculation and simulation calculation is very small. Theoretical calculation time is 5.5×10⁻⁷s and simulation calculation time is 600s, therefore the theoretical calculation time is much smaller than simulation time. In summary, the achieved method can greatly reduce the computation time while the accuracy of the calculation is kept.

Detection of olive oil adulteration is an important research focus and hard task. In this paper a new detection adulteration method based on a microfluidic chip was proposed. In the hydrodynamic focusing microchannel of the microfluidic chip, when DI water as the dispersed phase enters the continuous oil, DI water will be squeezed and cut into water-in-oil droplets. Size of droplets depends on fluid flow rate, oil viscosity and water-oil interfacial tension. With increasing adulteration, the viscosity of sample oils decrease monotonically, water-oil interfacial tension remains approximately constant, therefore the size of water-in-oil droplets will increase monotonically at the same flow rate. By analyzing the size of water-in-oil droplets, different oils can be successfully distinguished and evaluated. The microfluidic approach is simple, economic, and easy to use.

Hemispherical Resonator Gyroscope (HRG) is a new kind of high accuracy gyroscope that may has wide application in the future. The hemispherical shell is the key component of hemispherical resonator gyroscope, many researchers studied which but there’re a few models have been established. This paper studies the modeling and fabrication method of micro glass-blown shell intended to be used in HRG. A manufacturing method was proposed in the first, then the researchers established models to evaluate the height and thickness of the glass-blown shell. Eventually the research team carried out the corresponding experiment and got experiment data. Through the contrast of simulated result and experimental data, the theoretical models used during simulation are reasonable but still need to improve in next work.

In order to improve the resonant frequency and sensitivity of piezoresistive accelerometer, multi-objective optimization is proposed based on numerical simulation using the finite element software ANSYS. The first natural frequency (representing resonant frequency) and the maximal Mises stress (representing sensitivity) of accelerometer structures are defined as two objective functions, and the geometric parameters as design variables. After that, the metamodels of two objective functions are constructed using radial basis functions (RBF). Finally, multi-objective optimization is carried out with NSGA-II algorithm to generate Pareto front with the best tradeoff between two objective functions. The optimal results demonstrate that some Pareto front results of two objective functions are both improved compared to original design, and multi-objective optimization can elevate the compound performance of accelerometer structures.

A method of using MEMS supercapacitor as the secondary electric power supply of initiation control module was proposed. In allusion of the shortcoming that using ordinary capacitor as the secondary electric power of the penetration fuze has short discharge time, which restricts the signal processing function of the fuze. As supercapacitor has characteristics of large capacity and high overload resistance, six 33μF tantalum capacitors in parallel is replaced by The 20 mF supercapacitor as the secondary electric power supply. Test results show that the size greatly decreases and the discharge time of 0.2s increase to more than 3s, and the supercapacitor can be discharged stably under the condition of 90 thousand G to meet the requirements of the secondary power supply for the penetration fuze.

Meteorological information such as barometric pressure is important for meteorological disaster prevention, social security, scientific research and military field. Assessing the barometric pressure accurately and rapidly is the critical element to increase the performing efficiency of multiple tasks in abovementioned fields. But it is too difficult to ensure the accuracy and efficiency simultaneously due to the complexity of the environment. In this paper, we presented a novel radiosonde based on multiple MEMS sensors as the platform to research the influence of airflow on the system by simulation software. Then proposing a sort weighting algorithm to enhance the measurement accuracy of the barometric pressure up to 1% in theory. Finally, we verified the system could obtain the barometric pressure accurately and rapidly as we designed through the physical test.

With the development of economy and technology, the application areas of blasting equipment have continued to expand. But the blasting effect is usually not satisfactory in many blasting tasks because of the disadvantage of traditional blasting system such as weak timing accuracy, high misfire rate, poor security and complex operation. In response to the situation, we presented a novel high performance digital blasting network based on MEMS devices in this paper.

Thin film bulk acoustic resonators (FBARs) vibrate in the thickness mode, unfortunately the constraints of the lateral edge induce spurious lateral modes, which reduces the Q of FBARs and causes ripples in the passband of FBAR filters. In this work, 3D vibration model is established to simulate membrane-type FBARs. The impedance curves, the Smith charts and the dispersion curves are obtained to analysis and compare the lateral modes of FBARs with different shapes and size of the active resonator area and with different piezo layers. The simulation results show that FBARs with circular and irregular-pentagon active areas have smoother impedance curves and less spurious circles in the smith chart compared with rectangular ones. With the active areas of FBARs increasing, the influence of the spurious lateral modes decreases. While operating at the same resonance frequencies, apodized FBARs consisting of ZnO piezoelectric film suffer less from spurious lateral modes compared with the ones consisting of AlN.

Lead zirconate titanate (PZT) is widely used in microelectronics, optoelectronics, integrated optics and micro-electromechanical systems (MEMS) for its excellent ferroelectric, dielectric, pyroelectric and piezoelectric properties. As reported in the previous literature, PZT in the film form shows strong structural anisotropy. Therefore it is crucial to control film orientation to ensure the best ferroelectric properties. The (100) peak preferred oriented PZT thin films are significant for its excellent performance and widespread applications such as cantilevers, generators, transducers, etc. In this paper, the preparation and performance characterization of PZT thin films on the Pt/Ti/SiO2/Si wafers are discussed in order to get the films with fine (100) orientation and high quality ferroelectric properties. X-ray diffraction (XRD), scanning electron microscopy (SEM) and phase sensitive circuit are employed to characterize the physical properties of PZT prepared. Under the guidance of these approaches, the optimal fabrication parameters are obtained as follows: 350°C hot plate for 10 minutes and 650°C rapid thermal annealing (RTA) in oxygen flow for 10 minutes.

A 3D model of FCBGA is established, and the thermal-electrical coupling is simulated. The distribution of temperature, current density, temperature gradient, Joule heating under thermal-electrical coupling in solder bump is achieved. Effect of passivation layer opening dimension on electro-migration mechanism is analyzed, and current density evenness is defined to measure the degree of current density unbalance.

In order to improve the flawed method of testing and verifying of the MEMS security system on small caliber bullet, a mini-Hopkinson impact system is built, which is more suitable for MEMS security systems rapid verification test. This system is based on the original Hopkinson pressure bar system, which can easily control the speed of the bullets by firing them with electromagnetic coils. By adjusting the launch series and the charge voltage value, the system can output a numerically adjustable acceleration, whose maximum value can be as high as 45000g. The system just costs a few minutes for a test. Through the test of the impact system we can found that compared to the traditional high load test method, it is more convenient to use this system. It can offer a high-load impact, and the test frequency is higher. The result of the test is more accurate and easier to be monitored in real-time. This mini-Hopkinson impact system can test the threshold determination module effectively. Besides, it can also test other MEMS modules of Small caliber ammunition like MEMS gyroscope, etc.

Implementation and characterization of an biaxial optical interrogated micro displacement transducer are described in this paper. The sensor consists of an aperture in a bulk proof mass supported by the cantilever beams, source and detectors. Optical interrogation is performed by differential detection of the luminous power when the aperture is illuminated by a light emitting diode (LED). Simulation results have presented that the biaxial micro displacement transducer has a sensitivity of 8.75nA/µm in both x and y axis, and the measurement range is from -20µm to 20µm. This research provides an easy implementation structure to realize biaxial micro displacement measurement. In addition, optical interrogation combines the advantages of high accuracy and independent of electric feedback signal.

This paper presents a new fluid brush method for nanowire assembly, which has good commercial prospect. Firstly the design and principle of the method were described, and the key factors were analyzed theoretically through the laminar boundary layer model. Then a micro channel of 100 μm diameter was produced by PDMS and was used to build the experimental platform. Finally, this method was verified for its effectiveness experimentally. Experiments results show that this fluid brush method could be able to assemble parallel nanowire arrays by relative movement between a mechanical form and the fluid flow.

Aim at deficiency on anti-electromagnetism interference ability of the conventional fuze Safety and Arming (S&A) System under the complicated battlefield environment, a fuze S&A system is put forward based on MOEMS technology. The S&A system controls switching of laser transmission through microactuator, which performs the function of safety and arming. And it is detonated by laser. Simulation of the S&A system is made by ZEMAX. The conclusion is shown that the MOEMS S&A system can fuze the fuze when the optical circuit is disconnected, the safety function can be realized when the light path is on, and the ‘laser primer’ is successfully initiated. Electric energy is evaded when S&A system is being armed or detonated, which effectively improves the anti-interference ability of the S&A system.

Aiming at the condition that when a fuze MEMS S&A is subjected to setback overload, springback occurs after the clamping seat of the setback safety mechanism relieves locking of the explosive-proof sliding block so as to cause that the setback safety cannot be relieved smoothly, and then the explosive-proof sliding block cannot move in place, a compound safety mechanism based on setback-centrifugation two-environment-force is provided. The mechanism is characterized in that the original safety mechanism is separated to serve as a safety sliding block. ANSYS finite element simulation shows that under the action of setback overload, the clamping seat of the compound mechanism can relieve locking of the explosive-proof sliding block and release the explosive-proof sliding block; meanwhile, under the action of centrifugal force, the compound safety mechanism gets rid of restraint of the centrifugal locking device and moves to the direction opposite to the moving direction of the explosive-proof sliding block, and then the fact that the clamping seat of the safety mechanism rebounds and prevents the explosive-proof sliding block from moving is avoided, so as to ensure that the explosiveproof sliding block can move in place smoothly and the fuze S&A relieves setback safety. Therefore, selections and reference can be provided for designing of the setback safety mechanism of the MEMS S&A in the future.

Regarding the relative vertical motion of two plates in MEMS devices, the damping effect induced by film squeezing is critical to the dynamic characteristics of the devices. By using arrays of coupling inductors, the distribution of pressure between the two plates is stimulated by the distribution of the voltages in the inductor arrays. Based on the Reynolds equation, the equivalent circuit model is further proposed. The results show that the accuracy of the equivalent circuit model is close to that of the finite element model. This paper successfully converts the fluid domain to the electrical domain and is beneficial for the subsequent system-level simulation by directly put the MEMS devices with electronic circuits together.

Micro forming process is accompanied by the miniaturization of the feature size of parts, simultaneously influenced by the inner grain size of the material. With an intensified demand for miniature of the products at aerospace and activation industry, the micro-forming process at high temperature is much more popular than ever. However, it’s a pity that we don’t have much knowledge of high-temperature size effect. It’s of crude important to solve the fracture related issues of micro-forming process applied in a high-temperature ambient. A typical nickel superalloy, Inconel 718, is chosen in this article to study the interacted influence of temperature softening effect and grain size effect on the fracture mechanism. To elucidate this issue adequately, uniaxial tests at room temperature (25°C) and 800°C are conducted separately with specimens of five different grain sizes. Experimental results reveal that the fracture stress and strain of material are getting smaller with the increasing particle size Moreover, diverse sectional phenomenon is found at these temperatures and explained by the surface layer model. Furthermore, the fracture characteristics at high temperature is obtained by scanning transmission electron microscope, the number of micro-voids on fracture surface decreases with the particle size. The interacted effects of temperature and grain size on typical fracture characteristics are discussed in detail. It is an attractive work to reveal the evolution law of material fracture mechanism and characteristics at elevated temperature, thus this article provides an in-depth elaboration about HTMF (high-temperature micro-forming) process of great value.

In this paper, we propose a novel method of synthesizing multi-layered TiO₂ nanotubes. Through a repeated anodization process, TiO₂ nanotubes with 2 to 4 layers respectively are formed on a titanium foil, with every layer disconnected with each other and having a length of approximately 800 nm. We then further apply them as photo-anodes in dye-sensitized solar cells and test their photoelectric performance compared with the ordinary mono-layered nanotubes. As a result, due to the good light-harvesting and electron transportation capability, TiO₂ nanotubes with more layers prove more effective in the photoelectric conversion process and we believe they may have a very promising application prospect in the near future.

Triboelectric nanogenerator can harvest micro mechanical energy to electric energy and it will play an important role in the self-powering systems. Triboelectric nanogenerator with random-distributed microstructures on a PDMS film was firstly fabricated by using sandpaper of different mesh numbers as templates in this paper. The maximum output instantaneous voltage and the maximum short-circuit current can reach 2.6V and 0.25μA for a 4cm×1.5cm sample. Experiment results show that the open-circuit voltage rises with the increase of mesh number and frequency. The output voltage fluctuates in a definitive range periodically in about 125s and it increases sharply and then decays exponentially. That is quite different to that of nanogenerator with orderly micro/nano structures.

MEMS vibratory gyroscope has been widely used in military, automotive, and consumer electronics fields for its small size, low power consumption, high reliability, and impact resistance. Particularly, as one of the main directions of domestic and foreign research in the field of micro-gyroscope, the axial symmetry micro vibration gyroscope has higher quality factor, smaller frequency division and many other excellent characteristics. This paper gives a brief introduction of several typical structures of axial symmetry micro vibration gyroscope, then introduces the simulation and testing experiments of some axial symmetry micro vibration gyroscope we designed.

This paper proposes a type of stacked micromachined SIW (substrate integrated waveguide) filter using two-layer silicon substrate based on general Chebyshev filter theory. The stacked micromachined SIW filter is simulated using the commercial full-wave electromagnetic simulator HFSS and shows good performance. The results show that the passband of this filter is 32-35GHz. The return loss in passband is less than 18dB and the insertion loss of the filter in passband is less than 1.8dB. Compared with SIW filter on single layer substrate, such stacked filter can significantly improve its performance in size, cost, and easy integration with other planar circuits.

In this paper we present a novel fabrication technique for coherent population trapping based chip-sized alkali vapor cells. There are two cavities in the cell design, one is a reaction cavity for alkali dispenser and the other one is a working cavity for alkali storage. An alkali dispenser pill is placed in the reaction cavity and subsequently reacted to obtain pure alkali material. The alkali atoms can be transferred into the working cavity in vapor form once the cell is heated up to 70 degree. Since alkali reacts with many materials and cannot be handled in air, our method provides a low cost and high reproducible way to fabricate highly miniaturized vapor cells. Silicon micromachining and glass-Si-glass three-layer anodic bonding technology is applied to introduce alkali atoms and a buffer gas into the cell and effectively seal this environment within the cell. A rubidium vapor cell is demonstrated using our design. The cell size is 5×4×1.6 mm³, with hermetic seal leakage <5e⁻⁹ atm cc/s. Modulated optical absorption spectrum of the cell is obtained and matched with pure rubidium atom, indicating the suitability of these cells for use in highly miniaturized atomic frequency references based on CPT excitation scheme. In addition, the entire process is fabricated at the wafer level, with subsequent dicing into individual cells.

In this paper, we present a silicon based IPD structure combined with interposer for RF micro-system application. In our design, inductor, capacitor, resistor, CPW line and TSV are integrated on a high resistive silicon substrate, making it possible to realize system-on-chip integration of CMOS, MMIC and MEMS devices. Loss of the CPW line is 0.34db/mm @40GHz. The capacitance density reaches 1.05 fF/μm². The inductance for a 2.5-turn inductor is measured to be 8 nH, and the maximum Q factor is 16 @1.5 GHz. This CMOS-compatible fabrication technique provides a new approach for high level miniaturized RF micro-system.

To apply silicon-based wind energy harvesters (WEHs) in natural environments, it is significant to decrease the onset critical wind speeds. A MEMS piezoelectric WEH with an aluminum nitride film was fabricated, and then characterized in a small wind tunnel. The onset critical wind speed region with the lower and upper limits was observed in the experiments. When wind speed was lower than the lower critical speed, the electrical output was low and the vibration of the harvester was mainly the turbulence-induced vibrations modulated by its natural frequency. When wind speed was between the lower critical speed and the upper critical speed, strong wind-induced vibration appeared sometimes but cannot be sustained. When the wind speed was higher than the upper critical speed, the wind-induced vibration with large and stable amplitudes can be sustained and the electrical output was relatively high. The onset critical wind speed region strongly depends on the attack angle of the harvester. The measured lower and upper onset critical wind speeds of the MEMS harvester were about 4.0 m s⁻¹ and 4.4 m s⁻¹, respectively, when the attack angle was about 15°. The measured maximum output power was about 0.14 μW for the case with the attack angle of 0° when wind speed was 7.3 m s⁻¹.

Design and characterization of a micromachined accelerometer with optical interrogation is described in this paper. The mechanical part consists of an aluminum membrane on the bottom of a bulk silicon proof mass supported by the cantilever beams. Optical detection is performed by measuring the reflected diffraction orders when the grating is illuminated through a transparent substrate. Additionally, the model of electrostatic actuation is discussed to optimize the sensitivity of the optical accelerometer. The simulation results show the sensitivity is 18 nm/G in linear region, the measurement range is about 4.4 G if the wavelength of LD is 632 nm.

In this study, the fluorescence properties of Ferulic acid-Tb³⁺-SDBS system were studied. It was found that the addition of surfactant SDBS could enhance the fluorescence intensity of the system, a new pharmaceutical analytic method for the trace detection of ferulic acid content of drugs was also established. The fluorescence intensity of system with the excitation wavelength of 336nm and the emission wavelength of 545nm was monitored. The results showed that there was a good linear relationship between ferulic acid and the fluorescence intensity of the system while the concentration of ferulic acid in the range of 1×10⁻⁸∼4×10⁻⁶mol/L. The linear equation: If = 22.59 C+36.075, the correlation coefficient: r = 0.997.

Sulfur in the coal exists mainly in the following three forms: sulphate sulfur, iron sulfide sulfur and organic sulfur. Sulphate sulfur, which cannot burn in the air, is incombustible sulfur. What’s more, using national standard methods to determine sulphate sulfur content is process-complex and time-consuming. Using rapid detection method, the coal sample was ashed with slow ashing method, thus obtaining the sulfur content in coal ash using sulphur analyzer. Theoretically speaking, the method can get sulphate sulfur content in coal. Moreover, this paper analyzed precision and accuracy of rapid detection method, thereby obtaining the mathematical model of measuring the sulfate sulfur content utilizing rapid detection method and national standard method, which lays the foundation for promoting rapid detection method and formulating relevant standards.

The effects of purity of source material on fabrication of Al micro/nanowires via stress migration were investigated. Al source materials of 99.99% or 99% purity were used to deposit a thin Al film covered with a native oxide layer; annealing then formed Al micro/nanowires on the surface of each sample. The diameters and volumes of the formed wires were larger in the sample made using 99% Al, because of a decrease in the activation energy for grain boundary diffusion, and a corresponding increase in the atomic flux. Al micro/nanowires with controlled diameters and lengths can be formed by stress migration.

To figure out the relationship between the natural frequencies of microcantilevers and the environment temperature, the temperature coefficient of natural frequency for silicon microcantilevers was studied theoretically and experimentally. The theoretical temperature coefficient of natural frequency for single crystal silicon microcantilever was obtained by introducing the temperature variable into its expression of natural frequency. A dynamic testing system with low temperature loading unit was developed. In the system, the testing microstructures was excited by a base excitation device with the piezoelectric ceramics, and its vibration response was obtained by a Laser Dopper Vibrometer. Four silicon microcantilevers were tested under the low temperature ranging from −55°C to room temperature. The results show that the temperature coefficient of natural frequency for silicon microcantilevers is about from −3.35×10⁻⁵/°C to −2.95×10⁻⁵/°C, which is close to the result of theoretical analysis.

We fabricated a kind of flexible and nonenzymatic glucose sensor which consist of platinum nanoflower-working, platinum-reference/counter electrodes pair in a biplanar geometry and be contained separately on facing polyimide (PI) substrates. The PI film was coated with gold using a versatile electroless plating technology. The CNT-Nafion anti-interference inner layer, platinum nanoflower catalyst layer, and PU based mass transfer limitation layer are modified on working electrode surface layer by layer. Under the ideal test condition, the sensor’s sensibility greater than 0.01mA•mM⁻¹•cm⁻² with the linearity range from 0∼30mM. We study the morphology of glucose sensor’s each layer and its influence to the performance of glucose sensing. By virtue of the electroconductivity and porosity of CNT-Nafion network formed by electrophoresis, the glucose direct oxidase performance and the longtime stability of platinum nanoflower is enhanced, no obviously sensitivity decrease was found, the sensor is highly anti-interference to most of the electroactive materials like ascorbic acid or uric acid, promising be used in continuous glucose sensing.

Microfluidic chips coupled to electrospray ionization mass spectrometer (ESI-MS) have been comprehensively studied by researchers. The performance of joint electroosmotic and pneumatic driving force was investigated, based on our recently proposed poly(dimethylsiloxane) microfluidic chip with a corner-integrated emitter. The experiment and simulation flow rates, and the MS-coupling results of signal intensity and RSD indicated an optimal region showed excellent performance of this driving method. But externally imposed pressure driving force also brought problems. Electroosmotic driving played a significant role and using it as major driving was of great potential in the application of coupling to ESI-MS. As for portable MS for on-site analysis, highly integrated tiny microchip using electroosmotic driving solely would make a big difference.

Heteroatomic mesoporous Ce-MCM-41 molecular sieve was synthesized by using hydrothermal synthesis method. X-ray diffraction (XRD) and Infrared spectrophotometer (IR) results indicated that the well-ordered mesostructure was obtained and Ce had been introduced into the framework of MCM-41. Nitrogen adsorption-desorption results indicated that the average pore diameters of MCM-41 and Ce-MCM-41(Ce/Si molar ratio=0.04) were 3.24 and 3.85 nm, with pore volumes of 0.4256 and 0.8721 m³/g, Brunauer-Emmett-Teller (BET) surface areas of 587.65 m²/g and 612.35 m²/g respectively. The molecular size of dimethyl sulfide, calculated by using density functional theory (DFT), was 0.4648 nm, implying that the dimethyl sulfide easy accessed to the mesoscale pores of mesoporous molecular sieve. NH₃-TPD results illustrated that the acidity of Ce-MCM-41(Ce/Si=0.04) was stronger than that of MCM-41. As a result, for the adsorptive removal of dimethyl sulfide from nitrogen with a dimethyl sulfide content of 58 μg/g (that was 30 μg (S)/g), the desulfurization capacity of Ce-MCM-41(Ce/Si=0.04) was 7.52 mg(S)/g, higher than that of MCM-41 (4.57 mg(S)/g).

Optical microstructures which can produce a unique or particular optical performance have been widely applied in optical components such as light guides for display devices, micro-lens scanners, etc. Precision diamond turning based on a fast tool servo as a micro-displacement module is a very popular micro-structured surface manufacturing technology. Piezoelectric actuator is used as universal driving base of the FTS because of its high resolution and high stiffness. However, piezoelectric actuator exhibits hysteresis in their response to an applied electric field. In this paper, a series of first order reversal curves was tested to demonstrate the rate-dependent hysteresis properties of the FTS system. An exponential hysteresis operator was proposed to construct an expanded input space so as to transform the multi-valued mapping into a one-to-one mapping which enables neural networks to approximate the behavior of rate-dependent hysteresis of FTS. A hysteresis model using RBF neural networks of FTS was established based on expanded input space method, and closed loop control of FTS was applied using corresponding inverse model. Experimental results show a good agreement between the measured displacement curves and the predicted curves. Finally, the fabrication of complicated micro-structured surfaces has been carried out successfully.

Porous aluminum with high surface area for aluminum electrolytic capacitors was obtained by etching aluminum foils in hot hydrochloric acid solution under direct current (DC). Careful etching procedure produced parallel tunnels, in which numerous (100) faces was dissolved to form [001] etch tunnels. The porosity (ρ), average diameter (Ф) and average length (L) as well as the capacitance (C_p) of the etching tunnels were investigated in different etch conditions such as solution concentration, temperature and current density. Based on systematic study of the etching process, experimental parameters were optimized in obtaining porous aluminum with high specific capacitance. Growth mechanism of the porous aluminum was proposed based on the anodic polarization curves.

Anodes of aluminum electrolytic capacitor, which require large surface area for a high capacitance, are prepared in hot chloride solution to get numerous <100> etching tunnel. With the defect on the surface of the foils, the size and distribution of etch pits are not uniform. This paper compared the effect of five different pretreatment conditions on pitting corrosion of the anode aluminum foils by analyzing the morphology, the density and the distribution of the etching tunnels. It was shown that pretreatment with alkaline washing firstly to get rid of the oil stain and distorted oxidation film, and H₃PO₄ soaking sequentially to produce uniform oxide films, was beneficial for the uniform pitting corrosion.

Micro-opto-electro-mechanical systems (MOEMS) have been used to miniaturize traditional spectrometers successfully in the last decades. This paper present the optical system and realization strategy of a spectrometer based on torsional MOEMS scanning grating. The introduction of achromatic doublet in a modified Czerny-Turner optical layout enables the design of micro spectrometers capable of acquiring better effect of collimation and couple from light source. The research laid the foundation of optical design and serves for the further development.

Liquid crystal (LC) is a kind of special state between the solid and the liquid, and has both the fluidity of liquid and crystal anisotropy of the solid. These two features make the LC more active under the electrical, magnetic, and temperature field and micro flow which can be controlled precisely can be induced. This makes it possible that the LC can be used as the media for micro-fluidic driving and control field. In order to explore the characteristics and formation mechanism, and the overall features of the liquid crystalline micro-flows, a Micro-PIV system special for measuring the liquid crystalline micro flow was set up in this study. Besides, we did the experiments to measure the LC micro flow induced by the electric field and the temperature field with this system, and got more satisfactory results.

Novel process technologies for fabricating spherical silicon capacitive electrodes are introduced. Spherical electrodes can maximize the capacitance between the hemispherical resonator shell and themselves. However, due to the 3D curved surface, the resonator shell has always been damaged during the ICP etching process of electrodes. Novel methods combining a V-shaped mask and a multiple-step silicon structure are proposed to fabricate the electrodes. V-shaped mask, whose open window’s width gradually shrinks towards the center of the shell, can tune the average etching rate to be nearly equal throughout the electrode. Multiple-step silicon structure can make the thickness of the residual silicon, which is etched in the final ICP etching phase, to be approximately equal. Consequently, the damage of the shell is eliminated and the spherical electrodes with a radius of 500 μm have been fabricated successfully for the first time.

Atom packing structures of a large-angle tilt grain boundary between nano-grains in TiAl alloy are simulated at different temperatures by molecular dynamics simulations. Through the analysis of the average energy of the atoms and the atomic arrangements, these can be found that the atom packing in the grain boundary changes at different temperatures, there are different kinds of defects in the boundary and grain interior part, and Ti and Al atoms present different packing patterns.

SU-8 photoresist and electroforming based UV-LIGA process is an effective way to fabricate inertial switches. However, during the fabrication, the high stress in the SU-8 layers often causes them to detach from the substrate. To solve the detachment problem of SU-8 layers, a novel method was presented in this paper to release the internal stress in SU-8 layers by decreasing the area of electroforming layers. By using this method, a multi-scale inertial switch with ultra-high aspect ratio 17:1 was fabricated successfully. The overall size of the inertial switch is 14×11×0.6mm. The method presented in this paper can provide help to the fabrication of micro metal devices with large area and high aspect ratio.

Mechanochemistry provides a new method for surface modification of nanoparticles. It not only can prepare ultrafine powder, but also achieve its surface modification. Mechanochemical surface modification is a modification method of utilizing mechanochemical reaction during the ball milling, which modification effect is better than that of traditional modification method. The paper reviews the progress in the research of surface modification of nanoparticles by mechanochemical method, discusses the mechanism of modification and the research status of wet and dry mechanochemical surface modification. Some technological parameters of mechanochemical surface modification are emphatically considered. And the application of mechanochemical surface modification is introduced. Finally, some insights of coming research target and applications prospect of mechanochemical surface modification are anticipated.

We propose a new electrowetting-on-dielectric (EWOD) configuration using amorphous CYTOP^™ layer as both the insulating and hydrophobic layer. Sessile droplet experiments demonstrated the water contact angle can decrease up to 25° during electrowetting and the coating showed good durability. Typical droplet manipulations including transportation, mixing and splitting were achieved with 60 DCV power supply, which is significantly lower than previous report using other coating material such as poly(dimethylsiloxane) (PDMS). Hence, this simplified EWOD configuration using CYTOP^™ may have potential applications in many areas related with digital microfluidics.

In a cold region, the de-icing salt is often used to clean the pavement in winter, which makes the road in the environment of salt freezing cycle for a long time, and then affect the internal structure of the road. In this paper, uniaxial compressive creep test was carried out on SBS (styrene-butadiene-styrene) modified asphalt mortar after salt freezing, and the influence of different parameters on mechanical properties of asphalt mortar was investigated, and the microstructure changes of SBS modified asphalt and its mortar were analyzed by SEM. The results show that the structure of SBS asphalt was changed and its performance was declined after the salt freezing cycle, and the asphalt mortar appears spall in different degree, at the same time, it’s integrity, adhesion and surface crack size are changed.

A simulation system for the inductively coupled plasma (ICP) etching based on the narrow band level set method and geometric model [3] was presented. The narrow band level set method can describe the initial shape of the etching profile by computing the Hamilton-Jacobi function. The geometric model simplifies the model, and the etching process consists of etching rate and deposition rate. The system connects the users, base development, territory information and the system developers. A serious of simulations have been performed, and the simulation results match with the experimental results well.

While down-scaling of micro milling process is similar to the conventional process, there are specific issues that differ from macro machining due to higher ratios of feed per tooth to tool radius and tool run-out to tool diameter, size-effect, minimum chip thickness, elastic-plastic deformation, microstructure effects, etc. One of the challenges in micro machining is attaining accurate and reliable machining parameters, which can reduce tool wear and breakage to achieve higher productivity and quality at a lower cost. Therefore, this paper presents a new mechanistic model for predicting the precise process parameters considering material properties and principles of micro-milling under various cutting conditions. The proposed model also takes into account the nonlinearity and dynamics of minimum chip-thickness, micro-milling cutting forces considering cutting, as well as edge and damping coefficients into. The predicted stability lobes and the stability limits from experiments are in sufficient agreement. The research of micro-scale milling parameters is significant to improve the precision of machined parts, reduce the wear and tear of the micro-milling blade and extend the life of micro-tools.