A simple fabrication method of helical micro optical fibers (HMOFs) with controllable diameters and pitches based on micro-Weissenberg effect is proposed in this Letter. Single fibers with minimum diameter and pitch of 5 μm and 15 μm were directly written by near-field electrospinning of molten poly(methyl methacrylate) (PMMA). The morphology and transmission characteristics of single PMMA HMOFs were experimentally measured. The results showed that HMOFs have periodic modulation effect on transmitted light and show its potential as a micro-displacement sensor. Then a fluorescence detection structure based on HMOF is proposed, where HMOF was used to incoming the excitation light and collecting fluorescence. Experimental results show that for the fluorescence sensing of R6G aqueous solution, the fluorescence collection efficiency of HMOF was 4 times that of the micro optical fibers of the same diameter.
We study a novel fabrication method of micro/nano optical fiber by mechano-electrospinning (MES) direct-written technology. MES process is able to precisely manipulate the position and diameter of the electro-spun micro/nano fiber by adjusting the mechanical drawing force, which through changing the speed of motion stage (substrate). By adjusting the substrate speed, the nozzle-to-substrate distance and the applied voltage, the poly(methyl methacrylate) (PMMA) micro/nano optical fibers (MNOF) with controlled diameter are obtained and the tapered MNOF are fabricated by continuously changing the substrate speed. The transmission characteristics of PMMA micro/nano fiber is experimentally demonstrated, and a PMMA micro/nano fiber based refractive index sensor is designed. Our works shows the new fabrication method of MNOF by MES has the potential in the field of light mode conversion, optical waveguide coupling, refractive index detection and new micro/nano optical fiber components.
Aligned nanofibers, filament bundle composed of large number of nanofibers have potential applications such as bio-material, composite material etc. A series of electrospinning experiments have been conducted to investigate the electrospinning process,in which some parameters such as polymer solution concentration, bias voltage, distance between spinneret and collector, solution flow rate etc have been setup to do the experiment of nanofibers bundles construction. This work firstly reports electrospun nanofiber bundle through non-uniform electrical field, and nanofibers distributed in different density on electrodes from that between them. Thinner nanofibers bundle with a few numbers of nanofiber is collected for 3 seconds; therefore it's also possible that the addressable single nanofiber could be collected to bridge two electrodes.
Micro-electroplating technology has an increasingly wider application in the fabrication of MEMS devices. In order to fabricate a double-width cantilever beam which has three different electroplated areas. The proper composition of the bath solution is obtained through experiments firstly in the paper. Then the effects of the peak of current density, duty cycle and pause time on the surface morphology of the electroplated nickel are studied experimentally to make sure the regulating range of pulsed parameters. And at last the double-width cantilever beam is fabricated using lithographic, micro-electroplating and sacrificial layer releasing processes. The results show that the surface of the beam is bright and smooth, and the nucleation rate increases steadily. But the thickness of the three parts with different width is different which can be modified by increasing the duty cycle and reducing the current density to some extent.
Simulations and experiments on three kinds of Si tip fabrication techniques had been done, which are Anisotropic Dry Etching (ADE) , Anisotropic Wet Etching (AWE) and AWE combining with bonding. The simulation results showed that the parameters applied in the ADE and AWE should be controlled much more precisely than AWE combining with bonding to get expected tips. The exp eriments prove that the parameters of fabricating silicon tip by ADE and AWE have little
tolerance. The conclusions on AWE combining with bonding drew from simulations are verified in the detail experiments. From the simulations and experiments, excellent reliability and controllability are witnessed in AWE combining with bonding and a tip with top diameter within 23.44nm had been achieved.
System-level simulation, to which is paid much attention because of its multi-discipline, is a special requirement for MEMS analysis and design. In the article, an adaptive modeling methodology based on the evolutionary computation (ECM) is proposed, in accordance with the existed problems in present modeling. The lower order modals and the general independent functions are considered to construct the complete set. The dynamical equations of the reduced order model can be obtained. As an example, a static electrical actuator with micro cantilever is analyzed. The traditional modeling problems such as, how to find a good set of basic shapes, which elements should be selected in the base set, and how to construct the energy expression etc. can be solved by using ECM.