Design and fabrication of a new high gain multilayer negative refractive index metamaterial antenna for X‐band applications

This article presents the design of a planar high gain and wideband antenna using a negative refractive index multilayer superstrate in the X‐band. This meta‐antenna is composed of a four‐layer superstrate placed on a conventional patch antenna. The structure resonates at a frequency of 9.4 GHz. Each layer of the metamaterial superstrate consists of a 7 × 7 array of electric‐field‐coupled resonators, with a negative refractive index of 8.66 to 11.83 GHz. The number of layers and the separation of superstrate layers are simulated and optimized. This metamaterial lens has significantly increased the gain of the patch antenna to 17.1 dBi. Measurements and simulation results proved about 10 dB improvement of the gain.     

Polarization independent broadband metamaterial absorber for microwave applications

A new polarization independent broadband metamaterial absorber (MA) structure based on split ring resonators which are loaded with lumped elements and via connection lines is proposed. The designed structure shows a perfect absorption between 4 and 16 GHz which is validated by simulation studies. Experimental study is only made for the structure that has no via connections and no the lumped element resistors to show the importance of these entities in the proposed metamaterial structure. Both numerical and experimental study results show that broadband MA property depends on the resistors and via connections on the proposed structure. By having high absorption in a wideband range which is numerically demonstrated, the proposed structure can be used in energy harvesting or wireless power transfer applications with higher efficiencies.     

Polymer-based fabrication techniques for enclosed microchannels in biomedical applications

Investigations and analyses of body fluids like serum or whole blood are essential tasks in biomedical research in order to understand and diagnose diseases, to conduct pharmacological tests or to culture cells. Therefore, microfluidic systems provide a favorable tool for processing fluid samples as they allow downscaling of sample volumes and handling of single fluid components such as cells or proteins. For this reason, we present simple fabrication techniques for microchannel systems using polymer materials only. The demonstrated fabrication procedures are based on combinations of acrylic glass and the photo resists SU-8 and PerMX3020. On the one hand, these materials are low-priced compared to conventional silicon or glass. On the other hand, they have not shown any interaction with blood or other cell suspensions within the frame of our study. Furthermore, their transparency guarantees an easy observability of all processes within the system. Depending on the channel dimensions, different adhesion bonding techniques for closing of the systems are applied, whereas the fluidic interfaces are included by mechanical drilling. Summing up, we provide complete fabrication processes for fluidic systems which are simpler and more cost-effective than conventional methods and yet cope with all essential requirements for microfluidic applications.     

Multilevel beam SOI-MEMS fabrication and applications

A microfabrication technology has been developed and demonstrated, which enhances the capabilities and applications of high aspect ratio silicon-on-insulator microelectromechanical systems (SOI-MEMS) by enabling additional independent degrees of freedom of operation: both upward and downward vertical pistoning motion as well as bi-directional rotation. This is accomplished by applying multiple-mask high aspect ratio etches from both the front- and back-side of the SOI device layer, forming beams at different levels. The processes utilize four masks, two for front-side and two for back-side etching. As a result, single-crystal silicon beams with four different cross-sections are fabricated, and can be combined to form many additional beam cross-sections. This provides a wide variety of possible mechanical designs that can be optimized for optical and other applications. By this methodology, unique high aspect ratio micromirror devices were demonstrated with fully isolated and accurately self-aligned vertical combdrives in the SOI device layer, with initial combfinger overlap. Examples of fabricated devices are shown with performance summaries.     

Array waveguide grating model for nanoparticle sensor applications

The grating coupling surface plasmon polariton (SPP) waveguide is designed for nanoparticle sensors applications, where the properties of SPP waveguide model such as grating length and grating space length are designed with the Matlab and Optiwave programs. The propagation vector β of SPP grating slot waveguide is evaluated, from which the sensor applications model are simulated by the finite difference time domain method. The effective permittivity of the nanoparticle solution is evaluated. The sensor models are selected and the effective permittivity of the nanoparticle solution and used in the simulation model. The sensor activity of waveguides is determined with various values of the permittivity of grating space. The simulation result shows that the surface plasmonic TM₀ mode of the design model is depended on a resonance with input wavelength, period length, space length, number of the grating, the permittivity of grating space, and the nanoparticle concentration in grating space area. It shows that the cut off wavelength is shipped by the refractive index of grating space, while the result of simulation at some low IR wavelengths shows linear relative between H_y field intensity of TM₀ mode and grating space refractive index. The graph between H_y field intensity and concentration of nanoparticle solution also shows a good linear function, which has the good potential for sensor applications.

     

Design and fabrication of MEMS-based microneedle arrays for medical applications

Fabrication results for MEMS-based microneedle arrays are presented in this paper. The microneedle array was fabricated by employing a bi-mask technique to facilitate sharp tips, a cylindrical body and side openings. The presented array has advantages over previously published microneedle arrays in terms of ease of fabrication and bonding; high needle density and robustness; and side openings, which are expected to minimize the potential for clogging from skin debris during insertion. In addition, control over the process via etch-stop markers employed as stop layers, which assure the depth of long blind holes and the structure of the needle top, allows for different needle lengths and needle top structures to be easily implemented. The preliminary fluid flow and insertion experiments were performed to demonstrate the efficiency of the microneedle arrays.     

电子束辐照制作光波导技术研究进展

概述了采用电子束辐照制作光波导技术的研究历史,给出电子辐照对S iO2产生作用的机理、样品中原子错位的阈值、电子辐照深度的计算方法,分析了不同能量电子辐照产生折射率变化的原因,给出了低能电子辐照导致S iO2折射率变化的计算及测量方法,介绍了用电子束辐照制作光波导的进展。     

基于共平面波导的可调低通滤波器的设计和制作

介绍了一种使用多触点MEMS开关实现的新型可调微波MEMS低通滤波器,应用MEMS制作工艺在石英衬底上实现滤波器结构.滤波器基于慢波共平面波导周期性结构,具有尺寸小、插损低、可与单片微波集成电路工艺兼容等优点.滤波器截止频率的大小取决于MEMS开关的状态.实验结果表明,当MEMS开关受到激励时,低通滤波器的3-dB截止频率从12.5GHz转换至6.1GHz,带内纹波小于0.5dB,带外抑制大于40dB,开关的驱动电压在25V左右.     

Fabricating a hollow optical waveguide for optical communication applications

This work demonstrates a direct amorphous Si low-temperature wafer bonding technique to fabricate a semiconductor hollow waveguide with omni-directional reflectors for use in near infrared applications. The 2% dilute KOH solution was used to bond two ODR Si wafers with an amorphous Si thin film on the top of Si wafers. The resultant bonding interface is very thin, with a thickness that is close to that of the SiO/sub 2/ layer in the ODR substrate. Hence, the far-field image shows that light is strongly confined in the waveguides. The propagation loss was reduced to 1.0/spl plusmn/0.5 db/cm in the TE and TM modes, broadening the development of the semiconductor hollow waveguide with omni-directional reflectors for use in optical communication applications.     

A topology optimization method for design of negative permeability metamaterials

A methodology based on topology optimization for the design of metamaterials with negative permeability is presented. The formulation is based on the design of a thin layer of copper printed on a dielectric, rectangular plate of fixed dimensions. An effective media theory is used to estimate the effective permeability, obtained after solving Maxwell’s equations on a representative cell of a periodic arrangement using a full 3D finite element model. The effective permeability depends on the layout of copper, and the subject of the topology optimization problem is to find layouts that result in negative (real) permeability at a prescribed frequency. A SIMP-like model is invoked to represent the conductivity of regions of intermediate density. A number of different filtering strategies are invoked to facilitate convergence to binary solutions. Examples of designs for S-band applications are presented for illustration. New metamaterial concepts are uncovered, beyond the classical split-ring inspired layouts.     

Both transversal negative permeability and backward‐wave propagation in X‐Band waveguide with double‐side SRR metamaterials

In this article X‐band rectangular waveguides partially filled with the double‐side single ring resonator (DSRR) array are investigated for miniaturization, stop‐band, and multi‐band filters applications. Several rectangular waveguides loaded with the DSRR array in 2–10 GHz frequency band have been studied and optimized. We observe both the transversal negative permeability presented above the cutoff frequency and the backward‐wave located below the cutoff frequency with the DSRR array in X‐band waveguide. Both simulation and measurement results of DSRR array are with good agreement. The DSRR array provides better performance of the transversal negative permeability and the backward‐wave than the split‐ring resonator array. The physical explanation of backward‐wave is presented. The power loss distributions are clearly presented for the negative permeability attenuation and the backward‐wave propagation. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:240–246, 2016.     

一种基于SOI的集成光波导耦合系统的设计与制备

根据锥形光纤与平面环型微腔耦合原理,使用L-Edit版图设计软件设计并优化了锥形光波导与微腔耦合系统。利用MEMS工艺对SOI圆晶片进行加工,从而实现了锥形光波导与跑道型以及环型光波导微腔的集成。其中,光波导以及微腔通过ICP刻蚀顶层硅而成,矩形槽通过RIE刻蚀衬底硅而成。光波导两侧的矩形凹槽可方便光纤接人以及对出射光...     

Substrate integrated non-radiative dielectric waveguide and its applications

In this article a Substrate Integrated Non Radiative Dielectric Guide (SINRD) has been realized with the concept of substrate integration circuits. In SINRD, a specific pattern of air holes have been used grooved in a dielectric substrate to reduce the effective dielectric constant of a particular region. Accordingly, design and implementation of SINRD guides and its applications in millimeter wave subsystems have been investigated by using published literatures. Thereby the concept has been utilized to develop an optimized design flow of SINRD transmission line. Design has been carried out at W band (85–110 GHz) on a high dielectric constant substrate and subsequently dispersion characteristics has been studied subject to transmitted and radiated field configuration.

     

Micromechanical compartments for biotechnological applications: fabrication and investigation of liquid evaporation

Arrays of microcompartments for combinatorial chemistry and biotechnological applications have been fabricated by means of photolithography and anisotropic chemical wet etching. Integration levels of 25 000 per 4″ wafer have been achieved. Optically transparent membranes or microsieves allowing for rinsing between process steps can be incorporated. The liquid evaporation from the microcompartments has been investigated using compartments of different shape. The evaporation rate can be reduced by a factor of by using properly designed microcompartments with small openings. For the investigation of thermally biochemical reactions a microcompartment array with integrated thermo control has been developed, which allows the adjustment of thermal gradients over a 4″ wafer. Peak temperatures exceeding 90°C at the centre of the wafer as well as temperature gradients with ΔT=30°C can be demonstrated.     

Design,simulation and fabrication of LTCC-based microhotplate for gas sensor applications

Microsystem Technologies - This paper presents the design, simulation and fabrication of LTCC-based isothermally interconnected microhotplate. A thermal electric finite element analysis is used to...     

Implementation of hybrid fractal metamaterial inspired frequency band reconfigurable multiband antenna for wireless applications

In the present paper authors propose the design and analysis of a hepta band metamaterial inspired octagonal shape antenna using hybrid fractals for wireless applications. Multiband characteristics in the designed antenna is accomplished by introducing of slotted octagonal shape radiating part with hybrid fractal form of Moore curve and Koch curve and two SRR cells. The frequency band reconfigurability is obtained with aid of PIN diodes placed inside the strips connected between Moore curve (fused with centered Koch curve) and feedline. During ON mode of PIN diode antenna operates at seven microwave frequency S‐band WiMAX (3.4~3.69 GHz—IEEE 802.16e)/Lower C‐band terrestrial fixed and mobile broadband application (4.25~4.76 GHz)/C‐band WLAN (5.15~5.35/5.75~5.825 GHz—IEEE 802.11a] (5.4~5.9 GHz)/Lower X‐band Earth exploration‐satellite service ITU region 2 (7.9~8.4 GHz)/Upper X‐band Amateur satellite operating band (10.45~10.50 GHz)/Lower Ku‐band Radar communication application (13.25~13.75 GHz)/Middle Ku‐band Geostationary satellite service (14.2~14.5 GHz) covering various wireless applications. Proposed design exhibit hexa/hepta band features during OFF/ON mode of PIN diode. An acceptable gain, stable radiation characteristics, and good impedance matching are observed at all the resonant frequencies of the proposed structure.     

Design and fabrication of 3-dimensional helical structures in polydimethylsiloxane for flow control applications

Soft lithography in 2-dimensional (2-D) was developed for polymer MEMS applications about two decades back. The technique was highly useful for replication of microstructure molds using a soft polymeric material called PDMS (polydimethylsiloxane). From its inception the process has been widely applied to microfluidics, biochips, hybrid biomedical microdevices etc. However, it was limited to only surface microstructures and 3-Dimensional (3-D) soft lithography although performed by some research groups involved some very precise and expensive techniques like stereolithography etc. The exploration of soft lithography in three dimensions by using a replication technique with copper wires with micron size diameters was performed by our group relatively recently (Singh et al. in International conference on MEMS, IIT Madras, Chennai, 2009). In this work we have used the 3-D replication and molding technique to develop concentric solenoid patterns around micro-channels in the bulk of PDMS. The solenoidal paths of various pitches ranging from 0.4 to 1.2 mm have been replicated in PDMS using an innovatively designed fixture. The solenoids have been structurally characterized using an inverted fluorescence microscope (Nikon 80i) for dimensional parameters like pitch, length etc. Further, the solenoidal path designs have been simulated, optimized and fabricated around a central channel of 80 μ diameter and we have observed the repeatability of this fabrication process multiple times. The purpose of this architecture is to initiate valving action wherein fluid movement in the central channel can be restricted by filling the surrounding solenoidal track with compressed air at high pressure so that it can squeeze the centrally located micro-channel carrying the liquid. This valving structure may find a lot of applications in lab on chip devices, PCR biochips, biomedical micro-devices etc.     

Design and fabrication of compliant micromechanisms and structureswith negative Poisson's ratio

This paper describes a new way to design and fabricate compliant micromechanisms and material structures with negative Poisson's ratio (NPR). The design of compliant mechanisms and material structures is accomplished in an automated way using a numerical topology optimization method, The procedure allows the user to specify the elastic properties of materials or the mechanical advantages (MA's) or geometrical advantages (GA's) of compliant mechanisms and returns the optimal structures. The topologies obtained by the numerical procedure require practically no interaction by the engineer before they can be transferred to the fabrication unit. Fabrication is carried out by patterning a sputtered silicon on a plasma-enhanced chemical vapor deposition (PECVD) glass with a laser micromachining setup. Subsequently, the structures are etched into the underlying PECVD glass, and the glass is underetched, all in one two-step reactive ion etching (RIE) process. The components are tested using a probe placed on an x-y stage. This fast prototyping allows newly developed topologies to be fabricated and tested within the same day     

Modeling and optimization of the hot embossing process for micro- and nanocomponent fabrication

Hot embossing, a polymer molding process conceived by Forschungszentrum Karlsruhe, is one of the established replication processes for microstructures The process is especially well suited for manufacturing small and medium series of microcomponents (SPIE Conference 1997; Polymer News 25:224–229, 2000; J Micromech Microeng 14:R1–14, 2004; Sensors Actuators 3:130–135, 2000). However, a wider application of the process currently is seriously hampered by the lack of adequate simulation tools for process optimization and part design. This situation is becoming more critical, as the dimension of the microstructures shrink from micron and submicron levels to the nanoscale and as productivity requirements dictate the enlargement of formats to process larger numbers of devices in parallel. Based on the current scientific work (Forschungszentrum Karlsruhe, FZKA-Bericht 7058 2003; DTIP Conference Montreux 2004; Microsystem Tech 10:432–437 2004), a German–Canadian cooperation has been started. The objective of this cooperation is to fill the gap mentioned above by developing reliable computer models and simulation tools for the hot embossing process and to incorporate these models in a user-friendly computer code. The present paper will give an overview of the activities in the project. The activities related to material characterization, especially the development of a viscoelastic material model, the characterization of friction between polymer and mold during demolding, the development of an 8-in. microstructured mold, and the fabrication of nanostructured molds will be discussed.