This PDF file contains the editorial “How to Write a Good Scientific Paper: Picking the Right Journal” for JM3 Vol. 14 Issue 04

This PDF file contains the editorial “Special Section Guest Editorial:Special Section on the Interface of Holography and MEMS” for JM3 Vol. 14 Issue 04

Polymer-based holographic and diffractive optical elements have gained increasing interest due to their potential to be used in a broad range of applications, such as illumination technology, micro-optics, and holography. We present a production process to fabricate polymer-based diffractive optical elements and holograms. The process is based on maskless lithography, which is used to fabricate optical elements in photoresist. We discuss several lab-level lithography setups based on digital mirror devices and liquid crystal devices with respect to illumination efficiency, resolution, and contrast. The entire optical setup is designed with emphasis on low-cost components, which can be easily implemented in an optical research lab. In a first step, a copy of the microstructures is replicated into optical polymeric materials by means of a soft stamp hot embossing process. The soft stamp is made from polydimethylsiloxan, which is coated onto the microstructure in the photoresist. The hot embossing process is carried out by a self-made and low-cost hot embossing machine. We present confocal topography measurements to quantify the replication accuracy of the process and demonstrate diffractive optical elements and holographic structures, which were fabricated using the process presented.

This work describes the image formation and properties of holographic three-dimensional (3-D) display based on spatial light modulators (SLMs) combined with optical imaging systems. Existing pixelated SLMs with periodic mesh structures affect the holographic reconstruction and display properties. According to a holographic 3-D display architecture based on SLM in paraxial optical systems, this study applied the ray matrix optics and scalar diffraction theory to regard the light wave emitting from the holographic plane to the image plane as an optical system composed of four matrix elements. The image quality and depth of field (DOF) of the holographic 3-D display system are investigated, and the relationship between the impulse response and the matrix elements of the holographic imaging system is derived. In addition, the imaging properties and DOF are explored and verified through optical experimentation.

Lossy and near-lossless digital hologram compression methods are investigated to compress different complexities of wafer surface structures. In the lossy compression method, we apply row- and column-based uniform downsampling together with spline interpolation, whereas in the near-lossless compression method, we use wavelet local modulus maxima and spline interpolation. Results have shown that the lossy compression method is able to achieve a compression ratio of up to 100 for simpler wafer surface structures than that for complex surface structures. However, the near-lossless compression method is able to yield almost lossless compression even for complex wafer surface structures with a compression of about two. The proposed compression methods are computationally friendly for wafer surface structures as there is no time-consuming iterative computation involved.

We demonstrated optical-frequency-comb profilometry with a compressive sensing–based single-pixel camera composed of digital micromirror devices and a photodetector for measurement of large-depth objects. Use of two harmonic frequencies allowed us to measure an object with a meter-order depth without any 2π-phase ambiguity. Profilometry with 10×10 pixels using the 12th and 13th harmonics of the fundamental frequency of 76 MHz gave a noise level of ∼10 μm in terms of standard deviation. Linking the measurement results obtained using one and two frequencies gave an axial dynamic range of ∼3.9×10⁵.

We present the development of a holographic interferometer based on a dynamic hologram recording with photorefractive crystals of the sillenite family and which is adapted for the observation of MEMS. A compact portable system was already presented in the past and used in various metrology and nondestructive applications on large scattering objects. The great versatility of the instrument, which allows high-resolution measurements, was emphasized. We show the development and achievement of an optical module which can be easily interfaced on the basic instrument, allowing small specular objects’ observation. The results of deformation of electrically actuated MEMS are shown.

Today, spatial light modulators (SLMs) offer the world of digital holography a robust technology that can be incorporated into hologram recorders. This review surveys recent developments related to the role of SLMs in a family of incoherent digital hologram recorders termed Fresnel incoherent correlation holography (FINCH). Two systems branching out from FINCH, and discussed herein, are a confocal version of FINCH and a synthetic aperture FINCH-based system.

We give a summary of the progress we have made in the fabrication of guided wave devices for use in holographic video displays. This progress includes identifying anisotropic leaky-mode modulators as a platform for holographic display, the development of a characterization apparatus to extract key parameters from leaky-mode devices, and the identification of optimized waveguide parameters for frequency-controlled color display.

This paper discusses a method to measure the thickness of thin layers deposited on a reflective substrate. An interferometer with three wavelengths produces color interferences. A color sensor records the tint that is produced. The color interferences are approximated by a model based on the measurement of the laser intensities obtained with the reference mirror only. An iterative process leads to unambiguous algorithmic convergence and high accuracy thickness measurement. This method is simple, robust, compact, and single shot. The method does not need angular scanning over the field of measurement (about 75  mm²). The measurement on the surface yields a histogram of the thickness distribution and there is no requirement for any reference points (e.g., no need to make a groove or a walk on the layer). A thickness measurement performance of 50 nm was demonstrated for homogeneous polymer films deposited on a silicon wafer. The setup and digital image processing are discussed.

Pixelated spatial light modulators are used today in large quantities for projecting information. Apart from this standard application, the elements have found widespread use as dynamic changeable holograms for a multitude of applications ranging from microscopy over optical measurement systems to lithography. In this first part of our contribution, we give an overview concerning the necessary theory for the successful application of pixelated modulators in holography. We focus on the limitations imposed by current and future technology.

Dynamic holography can replace or enhance traditional basic optical functionalities within a lot of different optical systems. In particular, the possibility of considerably changing the function of a system is an important strength that is rarely possible in conventional optical systems. Today, different spatial light modulators can be employed in order to achieve dynamic holography, but most often liquid crystal on silicon phase modulators are used. We give an overview of applications for the usage of pixelated spatial light modulators in dynamic holography based on the functionalities that the dynamic holograms fulfill.

A microelectromechanical deformable mirror device that is optically addressed and designed to actuate at extremely low-light levels for wavefront error correction is fabricated and theoretically described. The device consists of an optically transparent substrate, a photoconductive detector, a thin-film resistor, and insulating posts that support a mirror. The mirror is suspended over the detector by the insulating posts and is deformed when the detector is illuminated through the substrate. The actuation of the device is theoretically modeled as a capacitor in series with a photoconductor under an external dc bias. Under an external 6.3 V dc bias and when back-illuminated with 501 μW∕cm2 light at 539 nm, a total mirror deformation of 474.3 nm was obtained and substantiated by numerical modeling. This represents the highest actuation sensitivity to date that results in mirror deflection values in hundreds of nanometers.

In traditional dual-wavelength digital holographic microscopy (DHM), a synthetic wavelength is obtained by using two lasers with different wavelengths, and the measurement range of the samples’ step height can be expanded from nanometers to micrometers. However, the measurement accuracy reduces along with the expansion of the measuring range, and significant noise is simultaneously introduced in this process. For cases where the sample’s step height is smaller than the wavelength of the illumination light, the measurement accuracy is very important. We present a new approach for dual-wavelength DHM. The synthetic wavelength is shorter than either of the two lasers, and thus higher measurement accuracy can be achieved. The numerical simulation and experiment results show the feasibility of this technique.

Digital holography (DH) in microscopy became an important interferometric tool in optical metrology when camera sensors reached a higher pixel number with smaller size and high-speed computers became able to process the acquired images. This allowed the investigation of engineered surfaces on microscale, such as microelectromechanical systems (MEMS). In DH, numerical tools perform the reconstruction of the wave field. This offers the possibility of retrieving not only the intensity of the acquired wavefield, but also the phase distribution. This review describes the principles of DH and shows the most important numerical tools discovered and applied to date in the field of MEMS. Both the static and the dynamic regimes can be analyzed by means of DH. Whereas the first one is mostly related to the characterization after the fabrication process, the second one is a useful tool to characterize the actuation of the MEMS.

We report on out-of-band (OoB) radiation that can cause degradation to the image quality in extreme-ultraviolet (EUV) lithography systems. We investigated the effect of OoB radiation with an EUV pellicle and found the maximum allowable reflectivity of OoB radiation from the EUV pellicle that can satisfy certain criteria (i.e., the image critical dimension error, contrast, and normalized image log slope). We suggested a multistack EUV pellicle that can obtain a high EUV transmission, minimal reflectivity of OoB radiation, and sufficient deep ultraviolet transmission for defect inspection and alignment without removing the EUV pellicle in an EUV lithography system.

Extreme ultraviolet (EUV) photons expose photoresists by complex interactions starting with photoionization that create primary electrons (∼80  eV), followed by ionization steps that create secondary electrons (10 to 60 eV). Ultimately, these lower energy electrons interact with specific molecules in the resist that cause the chemical reactions which are responsible for changes in solubility. The mechanisms by which these electrons interact with resist components are key to optimizing the performance of EUV resists. A resist exposure chamber was built to probe the behavior of electrons within photoresists. Resists were exposed under electron beam and then developed; ellipsometry was used to identify the dependence of electron penetration depth and number of reactions on dose and energy. Additionally, our group has updated a robust software that uses a first principles-based Monte Carlo model called low-energy electron scattering in solids (LESiS) to track secondary electron production, penetration depth, and reaction mechanisms within materials-defined environments. LESiS was used to model the thickness loss experiments to validate its performance with respect to simulated electron penetration depths to inform future modeling work.

We have developed organometallic carboxylate compounds [R_nM(O₂CR′)₂] capable of acting as negative-tone extreme ultraviolet (EUV) resists. The most sensitive of these resists contain antimony, three R-groups and two carboxylate groups, and carboxylate groups with polymerizable olefins (e.g., acrylate, methacrylate, or styrenecarboxylate). Evidence suggests that high sensitivity is achieved through the polymerization of olefins in the exposed region. We have performed a systematic sensitivity study of the molecules of the type R_nM(O₂CR′)₂ where we have studied seven R groups, four main group metals (M), and three polymerizable carboxylate groups (O₂CR′). The sensitivity of these resists was evaluated using E_max or dose to maximum resist thickness after exposure and development. We found that the greatest predictor of sensitivity of the R_nSb(O₂CR′)₂ resists is their level of polymerizable olefins. We mathematically define the polymerizable olefin loading (POL) as the ratio of the number of olefins versus the number of nonhydrogen atoms. Linear and log plots of E_max versus POL for a variety of molecules of the type R₃Sb(O₂CR′)₂ lend insight into the behavior of these resists.

In high-numerical aperture (NA) and hyper-NA lithography systems, the polarization aberration of the projection lens leads to imaging degradations. Typically, commercial simulators, which usually entail relatively higher computing cost and lack sufficient theoretical support, are used to explore the relationship. Analytical analysis of the impact of polarization aberration of the projection lens on the aerial image is performed. In the analysis process, an alternating phase-shift mask is used, and different components of the linear polarized illumination light vector are considered. The analytical expressions of image placement error (IPE) and best focus shift (BFS) caused by polarization aberration are derived from the intensity of the aerial image. The linear relationships between IPE and odd Pauli-Zernike polarization aberrations as well as that between BFS and even Pauli-Zernike polarization aberrations are established. Moreover, the polarization aberration sensitivities are given and compared when different components of the linear polarized illumination light vector are adopted. All derived expressions match simulation results well and can be used to understand more fully the detrimental impact of polarization aberration on lithographic imaging. The accuracy of the linear relationships is assessed by the least square method.

A lithography method is proposed for arbitrary patterning using an elliptically diverging laser diode beam focused with a single planoconvex elliptical microlens. Simulations are performed to model the propagation properties of the laser beam and to design the elliptical microlens, which has two different profiles in the x- and y-axis directions. The microlens is fabricated using an excimer laser dragging method and is then attached to the laser diode using double-sided optically cleared adhesive (OCA) tape. Notably, the use of OCA tape removes the need for a complicated alignment procedure and thus significantly reduces the assembly cost. The minimum focused spot of the laser diode beam is investigated by performing single-shot exposure tests on a photoresist (PR) layer. Finally, the practical feasibility of this lithography technique to generate an arbitrary pattern is demonstrated by dotted and continuous features through thin chromium layer deposition on PR and a metal lift-off process. The results show that the minimum feature size for the dotted patterns is around 6.23  μm, while the minimum linewidths for continuous patterns is 6.44  μm. In other words, the proposed focusing technique has significant potential for writing any arbitrary high-resolution pattern for applications like printed circuit board fabrication.

Pure thin films of organotin compounds have been lithographically evaluated using extreme ultraviolet lithography (EUVL, 13.5 nm). Twenty compounds of the type R₂Sn(O₂CR′)₂ were spin-coated from solutions in toluene, exposed to EUV light, and developed in organic solvents. Exposures produced negative-tone contrast curves and dense-line patterns using interference lithography. Contrast-curve studies indicated that the photosensitivity is linearly related to the molecular weight of the carboxylate group bound to tin. Additionally, photosensitivity was found to be linearly related to free radical stability of the hydrocarbon group bound directly to tin (R=phenyl, butyl, and benzyl). Dense-line patterning capabilities varied, but two resists in particular show exceptionally good line edge roughness (LER). A resist composed of an amorphous film of (C₆H₅CH₂)₂Sn(O₂CC(CH₃)₃)₂ (1) achieved 1.4 nm LER at 22-nm half-pitch patterning and a resist composed of (C₆H₅CH₂)₂Sn(O₂CC₆H₅)₂ (2) achieved 1.1 nm LER at 35-nm half-pitch at high exposure doses (600  mJ/cm²). Two photoresists that use olefin-based carboxylates, (C₆H₅CH₂)₂Sn(O₂CCH⏧CH₂)₂ (3) and (C₆H₅CH₂)₂Sn(O₂CC(CH₃)⏧CH₂)₂ (4), demonstrated better photospeeds (5  mJ/cm² and 27  mJ/cm²) but worse LER.

Source-mask optimization (SMO) is used in advanced computational lithography to further enlarge the process margin. SMO provides the source for subsequent optical proximity correction (OPC) to generate the mask with reasonable manufacturability and functionality. Little attention is paid to the mask optimization procedure of SMO. The procedure may potentially cause significant mismatch between a source-mask optimized mask (SMOed mask) and an optical proximity-corrected mask (OPCed mask), which affects the efficiency of the optimization. We investigate and report a specific example of an efficient method to align the SMOed mask to the OPCed mask so as to reduce the cycles of computational lithography and improve the predictability of SMO. This method incorporates techniques of retargeting and manipulating the cost function (CF) into SMO to modify the CF and eventually change the mask shapes. Various defects can also be corrected to minimize the needed number of hotspots, which also improves the effectiveness of SMO and decreases the cycles of computational lithography. Our sample simulations performed on a metal layer with both diffractive optical element (DOE) and freeform illumination demonstrate that the proposed SMO further enhances the process window (PW) by more than 30% compared with conventional SMO. The optimized mask shape is also more similar to OPCed mask. Experimental verification is also performed to validate the proposed method.

Microcolumns are widely used for parallel electron-beam lithography because of their compactness and the ability to achieve high spatial resolution. A design of an electrostatic microcolumn for our recent nanoscale photoemission sources is presented. We proposed a compact column structure (as short as several microns in length) for the ease of microcolumn fabrication and lithography operation. We numerically studied the influence of several design parameters on the optical performance such as microcolumn diameter, electrode thickness, beam current, working voltages, and working distance. We also examined the effect of fringing field between adjacent microcolumns during parallel lithography operations.

Laser direct-writing is an important technique for the fabrication of complex patterns. There is a continuous need for structures with increasingly small features, i.e., enhanced resolution. Focused radially polarized light is known to exhibit a narrow longitudinal polarization component. Here, a proof-of-concept is shown of enhanced resolution through polarization-selectivity by the selective recording of the longitudinal polarization component in a polarization-selective homeotropic and smectic B photoresist. The full-width-at-half-maximum (FWHM) of the fabricated spots in the polarization-selective resist is up to 56% smaller compared to the FWHM of the same spot in a photoresist that is not polarization-selective, which supports simulations that predict a theoretical maximum reduction of 62%.

Recent work has investigated the resonant dielectric reflectors for high-aspect ratio (AR) imaging and the necessary requirements for index-matching liquids (IMLs) at the prism/sample interface when imaging using a solid immersion Lloyd’s mirror interference lithography (SILMIL) system. These past results showed that SILMIL systems require a prism/IML refractive index (RI) (real component) mismatch less than approximately ±0.02 and an imaginary RI component ≤5×10−⁵ to achieve good reproducibility and uniformity of high-AR resist structures in the ultrahigh-NA (UHNA) regime without system gapping control. Here, we present simulated and experimental results for an index-matched prism/IML combination and for an IML with an imaginary RI component of ∼10−⁵. These results present the first SILMIL system that can produce both low- and high-AR resist structures over larger exposure fields than previously reported and without gapping control. We also present simulated and experimental results that show the AR process latitude, which further highlights the improved control compared with previous SILMIL research. Finally, we present simulated results from a materials survey that show new potential candidate dielectric underlayer materials that can accommodate high-AR imaging in the UHNA regime, some of which are better geared for the semiconductor industry.

Here, we present platinum and palladium mononuclear complexes with EUV photosensitivity and lithographic performance. Many platinum and palladium complexes show little or no EUV sensitivity; however, we have found that metal carbonates and metal oxalates (L₂M(CO₃) and L₂M(C₂O₄); M=Pt or Pd) are sensitive to EUV. The metal carbonates give negative-tone behavior. The most interesting result is that the metal oxalates give the first positive-tone EUV resists based on mononuclear organometallic compounds. In particular, (dppm)Pd(C₂O₄) (dppm=1,1-bis(diphenylphosphino)methane) (23) prints 30-nm dense lines with E_size of 50  mJ/cm². Derivatives of (23) were synthesized to explore the relationship between the core metal and the resist sensitivity. The study showed that palladium-based resists are more sensitive than platinum-based resists. The photoreaction has been investigated for two of our most promising resists, (dppm)Pd(C₂O₄) (23) and (Ph₂EtP)₂PdC₂O₄ (27). Our experiments suggest the loss of CO₂ and the formation of a zerovalent L₄Pd complex upon exposure to light. We have identified dppm₂Pd(δ(P)23.6) as the main photoproduct for (23) and (Ph₂EtP)₄Pd (δ(P)32.7) as the main photoproduct for (27).

Hybrid metrology, e.g., the combination of several measurement techniques to determine critical dimensions, is an increasingly important approach to meet the needs of the semiconductor industry. A proper use of hybrid metrology may yield not only more reliable estimates for the quantitative characterization of three-dimensional (3-D) structures but also a more realistic estimation of the corresponding uncertainties. Recent developments at the National Institute of Standards and Technology feature the combination of optical critical dimension measurements and scanning electron microscope results. The hybrid methodology offers the potential to make measurements of essential 3-D attributes that may not be feasible otherwise. However, combining techniques gives rise to essential challenges in error analysis and comparing results from different instrument models, especially the effect of systematic and highly correlated errors in the measurement on the χ2 function that is minimized. Both hypothetical examples and measurement data are used to illustrate solutions to these challenges.

Ge gate-all-around fin field-effect transistors (Ge FinFETs) with a capacitive effective thickness of a few nanometers have been successfully achieved via atomic-layer-deposited (ALD) high-dielectric Al₂O₃ on GeO₂/Ge and by adopting low-cost thermo ALD equipment. The MOS interface properties of the ZrO₂ or Al₂O₃/GeO₂/Ge structures have been studied systematically. It has been found that a GeO₂ interfacial layer that is greater than approximately 2.5 nm results in a significant degradation of the MOS interfaces, while an equivalent oxide thickness of <3  nm is still possible while maintaining good GeO₂/Ge interface quality. The Ge FinFET’s value has been demonstrated with the Al₂O₃/GeO₂/Ge gate stack prepared using a thermal ALD layer of Al₂O₃. The experimental results indicate that the MOS interface quality obtained with the technique developed for high-permittivity/Ge gate stacks is also extremely useful for the fabrication of triangle-fin complementary metal oxide semiconductor devices. An I_on/I_off ratio of 3.2×10⁴ and a subthreshold swing of 103  mV/dec were obtained for the triangular n-type Ge gate-all-around FET with (111) sidewalls. The drain current at V_GS−V_T=V_DS=−1.5  V is 88  mA/mm.

Polymer shrinkage from curing in nanoimprint lithography (NIL) strongly affects the ultimate shapes of two- and three-dimensional structures produced following etching. We computationally study the curing step in the NIL process and predict the shape changes caused by polymer shrinkage. The shape changes are predicted for crosses, diamonds with sharp and rounded tips, and multitiered structures that are applicable for multibit memory devices and dual damascene processes. The shape changes from curing are shown to be governed by the shrinkage coefficient of the polymer resist, its Poisson’s ratio, and the geometric aspect ratios of the shapes. Finite element simulations demonstrate that shape change due to polymer densification is equal to the average volumetric contraction of the resist material, but shrinkage is not isotropic and vertical displacement dominates. The thickness of the residual layer does not impact the final profile of the imprinted shapes considered. Further analysis shows that diamonds with sharp tips stay sharp while the tips of rounded diamonds get sharper. Additionally, shape changes for multitiered structures are not uniformly distributed among the tiers. Using etch simulations, we demonstrate the significant impact of polymer shrinkage on the final feature profile.

Evenly spaced conductive grids of copper and aluminum thin films on polyimide substrate are used for parabolic reflector antennas aboard telecommunications satellites. Laser microscribing of thin films using a flat-top and Gaussian laser beam profile is analyzed with 95% overlapping of the diameter of the laser spot. Laser scribing is performed using the Q-switched Nd³⁺:  YAG (355, 532 nm) laser. The influence of laser irradiation and beam shape on the scribed microchannel width, depth, and surface characteristics is experimentally analyzed using a noncontact optical profilometer and scanning electron microscope (SEM). Laser scribing using a flat-top profile produced near rectangular microchannels in copper thin films. Using the Gaussian profile, the probability of melting is greater than vaporization as observed using SEM images; this melt pool plays a prominent role in resolidification at the edges. The depth of the scribe channel is observed to be 20% higher for the 532-nm wavelength compared to the 355-nm wavelength. The effect of different environments such as air, water, and vacuum on the channel depth and quality is reported. The response of aluminum and copper thin films for high fluences is also studied. Thermal modeling of the laser-material interaction has been attempted by assuming the plasma electron temperature as the laser ablation temperature for modeling the recession rate and depth for a single laser pulse. Model results agree with experimental data showing greater depth for 532 nm compared to 355 nm.

The study of direct recording of the surface relief gratings on amorphous chalcogenide thin (2.5 to 5  μm films is presented by three different recording setups. Recording was performed on As₂S₃ by 532-nm wavelength laser light. Additionally, the evolution of a surface relief in dependence from the recording time and polarization has been investigated in detail and for the first time, the mass transfer process has been explained from the point of view of the photoinduced birefringence. The role of photoinduced plasticity in the formation of surface relief in amorphous chalcogenides during holographic recording has been discussed.

A dry development, directed self-assembly lithography (DSAL) hole-shrink process was studied, with a focus on the selectivity of the etching of poly(methyl methacrylate) (PMMA) over polystyrene (PS), and the suppression of etch stop. The highly selective etching of PMMA over PS was achieved using CO gas chemistry. However, it was found that the PMMA etching did not proceed beyond a certain depth. Scanning transmission electron microscopy and x-ray photoelectron spectroscopy analysis indicated that a deposition layer formed not only on the PS but also on the PMMA. The addition of H₂ to the CO plasma was effective in controlling the thickness of the deposition layer and in suppressing the etch stop. The CO/H₂ plasma process was combined with ion energy control to achieve a dry development for hole shrinkage. The dry development DSAL hole-shrink process was successfully realized by tailoring the etching gas chemistry and controlling the ion energy.

This article reports the results of the fabrication of large arrays of nanopillars for future tribological experiments. This fabrication focused on achieving a constant high aspect ratio up to 1∶24 and a separation between each pair of adjacent pillars. Electron beam lithography was used to write patterns in hydrogen silsesquioxane (HSQ) negative tone resist. To achieve nanopillars of high aspect ratios and with smooth sides, deep reactive ion etching was employed with SF₆ and O₂ at cryogenic temperatures. Finally, the residual HSQ was removed using CHF₃/O₂ plasma etching in order to obtain a smooth finish.

This paper provides a systematic review of the technical issues of SU8 fabrication for millimeter-wave and terahertz components based on research carried out at the University of Birmingham in the past decade. A design-for-manufacturability approach is followed. The flexibility of the SU8 process enables many device structures. Challenges and problems during fabrication will be discussed and demonstrated with examples. The measurement of the devices is also a significant challenge when the critical dimensions of the device shrink and special testing fixtures are needed in some cases. Finally, a brief overview of the issues discussed above is given for future guidance.

This paper presents a thermal-bubble-actuated microfluidic chip with cross-shaped microchannels for evaluating the effect of different microchannel designs on microparticle manipulation. Four cross-shaped microchannel designs, with orthogonal, misaligned, skewed, and antiskewed types, were proposed in this study. The thermal bubble micropump, which is based on a resistive bulk microheater, was used to drive fluid transportation, and it can be realized using a simple microfabrication process with a silicon-on-isolator wafer. Using commercial COMSOL software, the flow profiles of microfluidics in various cross-shaped microchannels were simulated qualitatively under different pumping pressures. Microbeads, with a diameter of 20  μm, manipulated in four cross-shaped microchannels, were also implemented in this experiment. The results showed that a skewed microchannel design has a higher sorting rate compared with orthogonal, misaligned, and antiskewed microchannels because its flow velocity in the main microchannel is significantly reduced by pumping pressure. Typically, the successful sorting rate for this type of skewed microchannel can reach 30% at a pumping frequency of 100 Hz.

An architecture of a torsional gyroscope having robust sense mode is reported. The robustness is achieved by utilizing dynamic amplification of torsional oscillations in the sense oscillator. The frequency response of the sense oscillator, which essentially is a 2-degree-of-freedom (DOF) one, has two resonance peaks and a flat region between the peaks, where the amplitude is less sensitive to ambient damping resulting in the robust sense mode. The frequency response of the 1-DOF drive oscillator has one resonance peak, which is designed to fall within the flat region of the sense amplitude. This helps in reducing the effects of change in the geometry and material properties of the device, induced by inevitable fabrication imperfections, on the device performance. The device is modeled by deriving the equations for electrostatic moment, moments of inertia, and spring constants. The design concepts of antiresonance and zero-phase frequency, along with analytical expressions for resonance frequencies and 3-dB bandwidth are also presented. The design is then realized using an SU-8 based ultraviolet-lithographie, galvanoformung, abformung (UV-LIGA) process having 8-μm thick Ni–Fe as the key structural layer. A characterization technique is developed to extract the frequency response of the fabricated device.

This work reports a simple, miniaturized optical sensing module for liquid refractometry. It is based on a stable Fabry–Pérot resonator consisting of two silicon cylindrical mirrors with a cylindrical lens in between. The lens is formed by a capillary tube through which the analyte passes. This setup enables volume refractometry, where light propagates through the sample realizing high-interaction depth. The cylindrical surfaces achieve light confinement, reducing the light escaping loss encountered in classical cavities with straight mirrors; hence, a high-quality factor (Q) over 1000 is attained. Exploiting this high Q, we adopt the refractive index (RI) measurement criterion: operating at a fixed wavelength and detecting the power drop as a consequence to the spectral shift with RI change. This technique showed that measuring RI change Δn above the RI of the reference solution can be determined for 0.0023<Δn<0.0045. Sensitivity up to 4094  dBm/RIU is achieved. A wider range is still achievable by the conventional method of tracing the shift in peak wavelengths: a range of Δn=0.0163  RIU can be scanned, with a sensitivity of 221  nm/RIU. Error analysis has been accomplished, and the device’s design parameters are discussed to evaluate the performance.

This PDF file contains the errata for “JM3 Vol. 14 Issue 04 Paper JM3-2015-0811-ERR” for JM3 Vol. 14 Issue 04