一种新颖的基于离子束刻蚀的纳米沟道制备技术

研究了一种新颖的基于MEMS工艺中离子束刻蚀的纳米沟道制备技术,通过研究离子束刻蚀微米级线条时,离子束刻蚀角度与刻蚀的轮廓形状之间的关系,在2μm线条内刻蚀出纳米沟道所需要的掩模图形,并结合KOH的各向异性腐蚀,成功获得了纳米沟道阵列.在两种不同的离子束刻蚀条件下,在2 μm图形内分别制备出单纳米沟道和双纳米沟道,最小宽度可达440 nm.     

Rectangular scale-similar etch pits in monocrystalline diamond

Etching of monocrystalline diamond in oxygen and water vapor at 1100 °C through small pores in a silicon nitride film produced smooth-walled rectangular cavities. The cavities were imaged by electron microscopy and measured by interferometric microscopy. The observed cavities ranged in width from approximately 1 μm up to 72 μm, in each case exhibiting smooth, vertical sidewalls, a flat bottom, and a depth equal to half its width. Cavity boundaries were determined to lie along slow-etching {100} crystallographic planes, suggesting the possibility of a powerful class of techniques for high-aspect-ratio bulk micromachining of diamond.     

Piston Motion Performance Analysis of a 3DOF Electrothermal MEMS Scanner for Medical Applications

MEMS scanners are useful for medical applications as optical coherence tomography and laser microsurgery. Although widespread design of MEMS scanners have been presented, their behavior is not well known, and thus, their motions are not easily and efficiently controlled. This deficiency induces several difficulties (limited resolution, accuracy, cycle time, etc.), and to tackle this problem, this article presents the modeling of an ISC electrothermally actuated MEMS mirror and the experimental characterization for the piston motion. Modeling and characterization are important to implement the control. A multiphysic model is proposed, and an experimental validation is performed with a good correspondence for a voltage range from 0 V to 3.5 V with a maximum displacement up to 200 µm and with a relative tilting difference of 0.1°. The article also presents a simple and efficient experimental setup to measure a displacement in dynamic and static mode, or a mirror plane tilting in static mode.     

Simulation-aided design and fabrication of nanoprobes for scanning probe microscopy

We proposed and demonstrated a flexible and effective method to design and fabricate scanning probes for atomic force microscopy applications. Computer simulations were adopted to evaluate design specifications and desired performance of atomic force microscope (AFM) probes; the fabrication processes were guided by feedback from simulation results. Through design-simulation-fabrication iterations, tipless cantilevers and tapping mode probes were successfully made with errors as low as 2% in designed resonant frequencies. For tapping mode probes, the probe tip apex achieved a 10 nm radius of curvature without additional sharpening steps; tilt-compensated probes were also fabricated for better scanning performance. This method provides AFM users improved probe quality and practical guidelines for customized probes, which can support the development of novel scanning probe microscopy (SPM) applications.     

DESIGN OF CANTILEVER PROBES FOR ATOMIC FORCE MICROSCOPY (AFM)

A cantilever beam used in an Atomic Force Microscope is optimized with respect to two different objectives. The first goal is to maximize the first eigenfrequency while keeping the stiffness of the probe constant. The second goal is to maximize the tip angle of the first eigenmode while again keeping the stiffness constant. The resulting design of the beam from the latter optimization gives almost the same result as when maximizing the first eigenfrequency. Adding a restriction on the second eigenfrequency result in a significant change of the optimal design. The beam is modelled with 12 DOF beam finite elements and the optimizations are carried through with either SLP (Sequential Linear Programming) or MM A (Method of Moving Asymptotes) and similar results are obtained.     

微电子机械系统中的压电薄膜微马达

本文提出了压电薄膜微马达的工作原理,介绍了该马达的优良性能、结构形式和加工工艺,最后指出了该马达研制的关键技术以及应用前景。     

Bacterial growth monitoring in a microfluidic device by confocal reflection microscopy

The feasibility of a method to nondestructively measure planktonic bacterial growth in a microfluidic device was addressed. Here, we report that the growth of Pseudomonas aeruginosa in a microfluidic device could be measured by a three-dimensional image analysis technique based on confocal reflection microscopy in a time-course.     

Effect of phase-lag on thermoelastic vibration of Timoshenko beam

Abstract

An explicit formula of coupled three-phase-lag (TPL) thermoelasticity theory under the Timoshenko beam is constructed for microbeam resonators. The constructed mathematical model is based on the modified couple stress theory which implies a prediction of size-dependent effects in microbeam resonators. By using Hamilton’s principle, governing equations for motion and boundary conditions are derived. The thermal moment and thermal deflection of microbeam resonators are studied analytically and numerically. A comparison of the results between modified coupled stress theory and classical theory is executed for TPL, GN-II, and Lord–Shulman (LS) models. Also, a comparison of the results between TPL, GN-II, and LS models for modified coupled stress theory is done. Besides, the result is presented for silicon microbeam for different aspect ratios and phase-lags. It demonstrated the result corresponding to the behavior of thermoelastic frequencies of microbeam resonators.     

Gas–surface interaction impact on heat transfer and pressure distributions of a high speed microchannel flow

The present work performs a computational study of a supersonic flow in a two-parallel-plates microchannel. Effects of incomplete surface accommodation on the surface properties of the microchannel were investigated by employing the Direct Simulation Monte Carlo (DSMC) method in combination with the Cercignani–Lampis–Lord (CLL) gas–surface interaction model. The work focuses the attention on the heat flux, pressure, and shear stress distributions on the parallel-plate surfaces due to differences in the accommodation coefficients of the lower and upper surfaces of the microchannel. It was found that accommodation coefficients have different influence on heat transfer, pressure and skin friction coefficients for the conditions investigated. The analysis showed that changes on the accommodation coefficients of the upper surface affected the wall pressure and the heat flux to the lower surface.     

Development of a compact displacement accumulation actuator device for both large force and large displacement

The design, fabrication, and testing of a compact displacement accumulation device is presented in this paper. The piezoelectric device provides both large displacement (mm) and large force (100 N). The device is based on conventional inchworm motor design that produces large displacement. The device integrates piezoelectric stacks for large force output and high-speed operation with MEMS ridges as a new clamping system. The device should be able to push and pull 450 N at 11 mm/s in a relatively compact size. FEM analysis is used for the design, EDM is used for the fabrication of a prototype, and conventional test techniques are used to evaluate performance. Stress and modal analysis are used to confirm that the device has an infinite fatigue life and a first modal frequency at 1309 Hz. Experimental data for clamping strength of the ridges and blocking force of the device validate that the device transfers the required load of 450 N. The device is successfully tested over a wide range of operating conditions at speeds up to 11 mm/s using open loop control. The stall load of the device is measured to be exceeding 2250 N. For the dynamic loading test, the device pushes test weights up to 50 N with the open loop control approach.