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We calculate the conversion from non-adiabatic, non-radial oscillations tidally induced by a hot Jupiter on a star to observable spectroscopic and photometric signals. Models with both frozen convection and an approximation for a perturbation to the convective flux are discussed. Observables are calculated for some real planetary systems to give specific predictions. Time-dependent line broadening and the radial velocity signal during transit are both investigated as methods to provide further insight into the nature of the stellar oscillations. The photometric signal is predicted to be proportional to the inverse square of the orbital period, $P^{-2}$, as in the equilibrium tide approximation. However, the radial velocity signal is predicted to be proportional to $ P^{-1}$, and is therefore much larger at long orbital periods than the signal corresponding to the equilibrium tide approximation, which is proportional to $P^{-3}$. The prospects for detecting these oscillations and the implications for the detection and characterisation of planets are discussed., Comment: 23 pages, 12 figures. Accepted for publication in MNRAS

International audience; We calculate the dynamical tides raised by a close planetary companion on non-rotating stars of $1$ $\text{M}_{\odot}$ and $1.4$ $\text{M}_{\odot}$. Using the Henyey method, we solve the fully non-adiabatic equations throughout the star. The horizontal Lagrangian displacement is found to be 10 to 100 times larger than the equilibrium tide value in a thin region near the surface of the star. This is because non--adiabatic effects dominate in a region that extends from below the outer edge of the convection zone up to the stellar surface, and the equilibrium tide approximation is inconsistent with non--adiabaticity. Although this approximation generally applies in the low frequency limit, it also fails in the parts of the convection zone where the forcing frequency is small but larger than the Brunt-V\"ais\"al\"a frequency. We derive analytical estimates which give a good approximation to the numerical values of the magnitude of the ratio of the horizontal and radial displacements at the surface. The relative surface flux perturbation is also significant, on the order of 0.1 % for a system modelled on 51 Pegasi b. Observations affected by the horizontal displacement may therefore be more achievable than previously thought, and brightness perturbations may be the result of flux perturbations rather than due to the radial displacement. We discuss the implication of this on the possibility of detecting such tidally excited oscillations, including the prospect of utilising the large horizontal motion for observations of systems such as 51 Pegasi.

The influence of deposition conditions on the residual stress of sputtered tantalum thin-film has been evaluated in the present study. Films have been deposited by DC magnetron sputtering and curvature measurement method has been employed to calculate the residual stress of the films. Transitions of tantalum film stress from compressive to tensile state have been observed as the sputtering pressure increases. Also, the effect of annealing process at temperature range of 90–300 °C in oxygen ambient on the residual stress of the films has been studied. The results demonstrate that the residual stress of the films that have been deposited at lower sputtering pressure has become more compressive when annealed at 300 °C. Furthermore, the impact of exposure to atmospheric ambient on the tantalum film stress has been investigated by monitoring the variation of the residual stress of both annealed and unannealed films over time. The as-deposited films have been exposed to pure Argon energy bombardment and as result, a high compressive stress has been developed in the films.

Optical lithography technique has been applied to fabricate devices from atomically thin sheets, exfoliated mechanically from kish graphite, bulk MoS2 and WSe2. During the fabrication processes, the exfoliated graphene, few-layer MoS2 and WSe2 sheets have been patterned into specific shapes as required and metal contacts have been deposited on these two-dimensional sheets to make field effect devices with different structures. The key to the successful implementation of the technique is the appropriate alignment mark design, which can solve the problems of aligning photomasks to the random location, orientation and irregular shape exfoliated two-dimensional sheets on the substrates. Raman characterization performed on the patterned two-dimensional sheets after the fabrication processes shows that little defects have been introduced during fabrication. Field effect has been observed from I-V characteristics with the highly doped silicon substrate as the back gate. The extracted field effect hole and electron mobilities of graphene are ~1010cm2V-1s-1 and ~3550cm2V-1s-1 respectively; and the field effect carrier mobilities of MoS2 and WSe2 are ~0.06cm2V-1s-1 and ~0.03cm2V-1s-1, separately, which are comparable with experimental results of other reports. Display Omitted Optical lithography has been applied for the fabrication of 2D electronic devices.The exfoliated graphene, few-layer MoS2 and WSe2 sheets have been patterned.The key to the successful implementation is the appropriate alignment mark design.The final electronic devices show little defects.

Electrodeposited alloys of nickel and iron are prone to suffer from the development of undesirable-stress gradients resulting from process steps and heat treatments following deposition. As a result, the yield associated with devices using permalloy (Ni–Fe, 80%–20%) films can be severely compromised. Although electrodeposition recipes have been formulated that greatly reduce stress in Ni–Fe films, any stress gradients through the thickness of permalloy can pose considerable problems during the release of cantilevers. The development of such gradients is typically the direct result of the selected design and process architecture and/or problematic material choices. This paper presents an improved architecture for electroplated Ni–Fe freestanding microcantilever structures. This architecture minimizes the development of stress gradients in cantilever beams and facilitates the use of suspended permalloy cantilever structures in magnetically actuated microelectromechanical systems (MEMS) switches.[2014-0170]

Monolayer graphene resonators have been fabricated with up to 3mm in length.Resonators exhibit mechanical stability with ultra high aspect ratio.Raman spectra proved graphene to be of high quality.Interferometery profiling of the membranes shows very little sagging.Resonance frequency can be matched with analytical model for thin membranes. Display Omitted Graphene resonators have been fabricated in rectangular and circular geometries ranging from 1 to 3mm in diameter. The resonant frequencies have been measured, and fitted to an analytical model. An optical profile of the graphene sheet has been taken, and the monolayer graphene has been confirmed to be of high quality using Raman spectroscopy. The graphene membranes have shown hookean behaviour with no evidence of deformation. The characterisation of the single layer graphene sheet on this large scale provides new information previously unavailable on the mechanical stability of graphene with ultra high aspect ratio.

A novel technique for the production of nanoscale electrode arrays that uses standard microfabrication processes and micron-scale photolithography is reported here in detail. These microsquare nanoband edge electrode (MNEE) arrays have been fabricated with highly reproducible control of the key array dimensions, including the size and pitch of the individual elements and, most importantly, the width of the nanoband electrodes. The definition of lateral features to nanoscale dimensions typically requires expensive patterning techniques that are complex and low-throughput. However, the fabrication methodology used here relies on the fact that vertical dimensions (i.e. layer thicknesses) have long been manufacturable at the nanoscale using thin film deposition techniques that are well established in mainstream microelectronics. The authors report for the first time two aspects that highlight the particular suitability of these MNEE array systems for probe monolayer biosensing. The first is simulation, which shows the enhanced sensitivity to the redox reaction of the solution redox couple. The second is the enhancement of probe film functionalisation observed for the probe film model molecule, 6-mercapto-1-hexanol compared with microsquare electrodes. Such surface modification for specific probe layer biosensing and detection is of significance for a wide range of biomedical and other sensing and analytical applications.

Recent literature suggests that glia, and in particular astrocytes, should be studied as organised networks which communicate through gap junctions. Astrocytes, however, adhere to most surfaces and are highly mobile cells. In order to study, such organised networks effectively in vitro it is necessary to influence them to pattern to certain substrates whilst being repelled from others and to immobilise the astrocytes sufficiently such that they do not continue to migrate further whilst under study.In this article, we demonstrate for the first time how it is possible to facilitate the study of organised patterned human astrocytic networks using hNT astrocytes in a SiO2 trench grid network that is inlayed with the biocompatible material, parylene-C. We demonstrate how the immobilisation of astrocytes lies in the depth of the SiO2 trench, determining an optimum trench depth and that the optimum patterning of astrocytes is a consequence of the parylene-C inlay and the grid node spacing. We demonstrate high fidelity of the astrocytic networks and demonstrate that functionality of the hNT astrocytes through ATP evoked calcium signalling is also dependent on the grid node spacing. Finally, we demonstrate that the location of the nuclei on the grid nodes is also a function of the grid node spacing.The significance of this work, is to describe a suitable platform to facilitate the study of hNT astrocytes from the single cell level to the network level to improve knowledge and understanding of how communication links to spatial organisation at these higher order scales and trigger in vitro research further in this area with clinical applications in the area of epilepsy, stroke and focal cerebral ischemia.

Conductive carbon films are highly attractive for use as electrodes in electrochemistry and biosensing applications. Patterned photoresist films can be transformed into carbon electrodes using standard photolithographic techniques followed by pyrolysation of the photoresist in a furnace under a reducing atmosphere. Previous studies have been made of the electrical properties of blanket carbon films created using this method of fabrication. However, there is a need to investigate pattern dependent effects, particularly the extent to which the dimensions of the patterned films shrink during the high temperature processing. This study applies microfabricated test structures to the process characterisation of conductive carbon produced from standard positive photoresists.

Silicon based integrated circuit technology has shown astonishing progress scaling to smaller geometries as the industry follows Moore's predictions. However, in recent years the cost associated with staying at the leading edge of silicon IC technology has resulted in many companies being either unable, or unwilling, to afford the investment required. As a consequence some have decided to use foundry technology and/or diversify into new device types and associated novel application areas. All of these diverse Silicon + technologies have one particular feature in common, namely they all use silicon as a platform for system integration with the added value being the innovation associated with post-processing and/or technology integration, which in many cases is realised on standard foundry technology. This paper examines many of the issues associated with integrating foundry and custom IC wafers with both new materials and technologies such as MEMS based sensors and actuators. In particular it examines the various options available for companies considering Silicon + technology applications and presents examples of successful applications of this approach. Some of these are illustrated below.

Test structures have been fabricated to allow electrical critical dimensions (ECD) to be extracted from copper features with dimensions comparable to those replicated in integrated circuit (IC) interconnect systems. The implementation of these structures is such that no conductive barrier metal has been used. The advantage of this approach is that the electrical measurements provide a nondestructive and efficient method for determining critical dimension (CD) values and for enabling fundamental studies of electron transport in narrow copper features unaffected by the complications of barrier metal films. This paper reports on the results of tests which have been conducted to evaluate various extraction methods for sheet resistance and line width values from the current design.

Test structures have been used to study the feasibility of bonding MEMS to CMOS wafers to create an integrated system. This involves bonding of prefabricated wafers and creating interconnects between the bonded wafers. Bonding of prefabricated wafers has been demonstrated using a chemical-mechanical polishing enabled surface planarization process and an oxygen plasma assisted low temperature wafer bonding process. Two interwafer connection approaches have been evaluated. For an oxide bonding approach, interconnects between wafers are established through contact vias, using a standard multilevel metallization process after the wafer bonding process. Resistances of 3.8-5.2 Omega have been obtained from via chain test structures and an average specific contact resistivity of 1.7 X 10-8 Omega cm2, measured from the single via Kelvin structures. For a direct metal contact approach, electrical connections have been achieved during the bonding anneal stage due to stress relief of the aluminium film.

Astronomical instruments for measuring Cosmic Microwave Background polarisation, such as CLOVER, require large arrays of Superconducting Transition Edge Sensors (TESs). We report recent results from a processing route development aimed at high yield fabrication of microstrip-coupled TESs. The incoming signal is delivered onto a silicon nitride membrane by means of a superconducting microstrip transmission line. This transmission line is then terminated with a thin-film load resistor. The wafer-based fabrication route of the Mo/Cu TESs gives highly reproducible device characteristics in terms of superconducting transition temperature, electrical and thermal characteristics. An overall device yield of 65% has been achieved for a multi-wafer processing run.

The enhancement of the second flexural mode in a monolayer graphene resonator by an inhomogeneous electrostatic actuation force has been observed. The devices have been fabricated by transferring the graphene onto a poly-Si/SiO2/Si substrate whereby the poly-Si has been released to produce graphene resonators. Enhancement of the second harmonic has been demonstrated by varying the actuation voltage, achieving an amplitude enhancement of up to 95% of the fundamental mode. The reported findings open new perspectives for graphene resonant sensors with enhanced sensitivity.

This paper reports the latest design and the associated fabrication technology of the Mk II prototype infrared (IR) detector for the two 5120 pixel SCUBA-2 (submillimetre common user bolometer arry) instruments, which are to be mounted on the James Clerk Maxwell telescope (JCMT) in Hawaii. Progress is described on the design and the technology modules being developed for the new detector, which is based upon silicon micromachining. The two arrays of transition edge sensors (TES) are used to detect incoming radiation with wavelengths of 450 and 850 μ respectively and as the SCUBA-2 detector operates at about 100 mK, it consequently involves integration with low-temperature electronics and careful design of the associated interconnect. A key aspect of the connection between the TES detector and readout electronics is the use of indium flip-chip bumps, which become superconducting at cryogenic temperatures. The integration of nanoscale membranes and transition edge sensors together with microsystem technology enables SCUBA-2 to have of the order of 10 -17W (1 Hz bandwidth) sensitivity to incoming radiation.

Cell patterning platforms support broad research goals, such as construction of predefined in vitro neuronal networks and the exploration of certain central aspects of cellular physiology. To easily combine cell patterning with Multi-Electrode Arrays (MEAs) and silicon-based ‘lab on a chip’ technologies, a microfabrication-compatible protocol is required. We describe a method that utilizes deposition of the polymer paryleneC on SiO2 wafers. Photolithography enables accurate and reliable patterning of parylene-C at micron-level resolution. Subsequent activation by immersion in fetal bovine serum (or another specific activation solution) results in a substrate in which cultured cells adhere to, or are repulsed by, parylene or SiO2 regions respectively. This technique has allowed patterning of a broad range of cell types (including primary murine hippocampal cells, HEK 293 cell line, human neuron-like teratocarcinoma cell line, primary murine cerebellar granule cells, and primary human glioma-derived stem-like cells). Interestingly, however, the platform is not universal; reflecting the importance of cell-specific adhesion molecules. This cell patterning process is cost effective, reliable, and importantly can be incorporated into standard microfabrication (chip manufacturing) protocols, paving the way for integration of microelectronic technology.

This paper reports the application of test structures to the evaluation of tantalum nitride (Ta-N) as a material for integration with high temperature electronics. The test structure fabrication involves the reactive sputtering of Ta-N and its consequent annealing in a vacuum to reach the target specifications of low temperature coefficient of resistance (TCR). A test wafer has been designed to both evaluate the temperature performance of thin films and to study the possibility of integrating different metal films into a single sensing device. The Ta-N resistors resulting from this work have a TCR of −150 ppm/°C which remains stable after 6 hours of annealing at 600°C.

Prototype imaging subarrays for SCUBA-2 (the Submillimeter Common-User Bolometer Array) have been fabricated and tested. The pixel count (1280) of these wafer-scale imagers is significantly larger than any other low-temperature detectors produced to date, and represents a major step forward for the low-temperature detector community. These transition-edge-sensor (TES) based imagers utilize several innovations including in-focal-plane superconducting quantum intereference device (SQUID) multiplexers, micromachined Si block absorbers, and superconducting wafer hybridization. In this paper, we review the fabrication processes developed for these imagers and present recent optical data from a prototype imaging subarray.

This paper describes the use of 800nm femtosecond infrared (IR) and 248nm nanosecond ultraviolet (UV) laser radiation in performing ablative micromachining of parylene-C on SiO2 substrates for the patterning of human hNT astrocytes. Results are presented that support the validity of using IR laser ablative micromachining for patterning human hNT astrocytes cells while UV laser radiation produces photo-oxidation of the parylene-C and destroys cell patterning. The findings demonstrate how IR laser ablative micromachining of parylene-C on SiO2 substrates can offer a low cost, accessible alternative for rapid prototyping, high yield cell patterning.

An improved bottom-up electroplating technique has been successfully developed for the fabrication of TSV arrays with 9.5:1 aspect ratios. 125,500 TSVs have been fabricated in an area of 6×6 cm with a horizontal and vertical pitch of 240 μm. A method of visually inspecting the via yield is presented, and Kelvin test structures and contact chain test structures have been fabricated to electrically evaluate single and multiple TSVs respectively. The average resistance of the Cu vias was measured as of 9.1 mΩ using the Kelvin contact resistance structures.

Surface acoustic waves (SAW) generated in a piezoelectric substrate may be used to manipulate micro-scale droplets of liquid in a digital microfluidic system for lab-on-a-chip applications. The wettability of the surface over which a droplet is driven determines the ease and speed with which the droplet is propelled. This provides the opportunity to achieve fine control of SAW driven droplets simply by patterning of the surface into areas with different levels of wettability. This paper evaluates a number of different materials and surface preparation techniques and assesses their manufacturability and efficacy for this application. Test structures have been designed and developed to help optimise a fabrication process using the biocompatible polymer Parylene. Early results obtained using airflow as a driving force show that it is possible to manipulate droplets through direction changes of up to 60 #x00B0;. Additional work has been done using surface acoustic waves as the driving force to determine the extent to which droplets can be guided to desired locations.

This paper presents details of the design and fabrication of test structures specifically designed for the characterization of two distinct digital microfluidic technologies: electro-wetting on dielectric (EWOD) and surface acoustic wave (SAW). A test chip has been fabricated that includes structures with a wide range of dimensions and provides the capability to characterize enhanced droplet manipulation, as well as other integrated functions. The EWOD and SAW devices have been separately characterized first of all to determine whether integration of the technologies affects their individual performance, including device lifetime evaluation. Microfluidic functions have then been demonstrated, including combined EWOD/SAW functions. In particular, this paper details the use of EWOD to anchor droplets, while SAW excitation is applied to perform mixing. The relationship between test structure designs and the droplets anchoring performance has been studied.

This paper presents a methodology together with a characterisation system for rapidly and quantitatively evaluating the lifetime and reliability of Electro-Wetting-on-Dielectric (EWOD) microfluidic devices. By studying the contact angle (CA) change when electrowetting forces are applied on the test structure, the number of times of a droplet can be switched between relaxed and actuated states can be characterised. This paper describes the development of an automated measurement system together with test structures designed to quickly characterise and optimise EWOD dielectric layer compositions. This enables the rapid determination of the driving voltage that results in the longest lifetime of the device, providing the tools to optimise both the process, architecture and the voltage driving scheme.

The paper proposes a micromachined antenna on a silicon substrate for Aerospace applications. The research focuses on the feasibility of fabricating antennas using standard fabrication and 3D integration techniques to develop a single chip solution for wideband/multiband communication devices.

Current and future astronomical instruments require large arrays of Superconducting transition edge sensors (TESs). Of particular importance are microstrip-coupled TESs, where the incoming signal is delivered onto a silicon nitride membrane by means of a superconducting microstrip transmission line. This transmission line is then terminated with a thin-film load. We report on a wafer-based fabrication route for molybdenum/copper microstrip-coupled TESs that gives highly reproducible superconducting transition temperatures, and electrical and thermal parameters. Although a large array of voltage-biased TESs will operate satisfactorily with widely varying individual pixel characteristics, uniformity of the characteristics is clearly advantageous from an operational point of view in terms pixel to pixel variations in responsivity, power handling and noise. An overall device yield of 65% has been achieved for our first multi-wafer production run.

The novel overlay test structure reported in this paper was purposely designed to serve as an application-specific reference material. It features standard frame-in-frame optical overlay targets embedded in electrical test features and fabricated by the same process as the parts being manufactured. Optical overlay is commonly used in process control applications due to its utility for determining the relative positions of features patterned in photoresist. Electrical overlay, although it can only be measured on fully patterned test structures, is the metric of interest. Using this combined optical/electrical overlay test structure, we can derive the relationship between the routinely measured optical overlay and the electrical overlay for any specific combination of process and optical overlay tool.

This paper characterises a novel Chemical Mechanical Polishing (CMP) based process for the fabrication of nanometer wide transducer gaps for RF MEMS resonators. The process requires one photolithographic step less than previously reported fabrication methods and does not super from transducer gap widening, which otherwise strongly affects the impedance of manufactured resonators. CMP test masks were used to evaluate the ability to produce nanometer wide planarised capacitive transducer gaps and to determine the planarity of CMP based processing. As a result of this work, pattern dependent removal rates for polysilicon have been determined and design guidelines defined to optimise the yield of CMP fabricated resonators.

A novel copper damascene process is reported for fabrication of electrical critical dimension (ECD) reference material. The method of fabrication first creates an initial "silicon preform" whose linewidth is transferred into a trench using a silicon nitride mould. The trench is created by removing a portion of the silicon and replacing it with copper to enable both transmission electron microscopy (TEM) and electrical linewidth measurements to be made on the same structure. The technique is based on the use of anisotropic wet etching of [110] silicon wafers to yield silicon features with vertical sidewalls. The paper demonstrates that this method successfully produces copper lines which serve as ECD control structures and the process can be applied to any damascene compatible material for developing electrical linewidth measurement reference material.

Test structures have been used to demonstrate the feasibility of bonding MEMS and CMOS wafers to create an integrated system. This involves using low temperature bonding along with CMP planarisation and wafer thinning. The last step in the integration process is bringing the electrical connections to the top surface and the creation of interconnect between the wafers. Test structures to evaluate this process have been designed and fabricated resulting in 7-9 /spl Omega/ resistances for via chain structures. Via contact resistances of 6 /spl times/ 10/sup -8/ /spl Omega//spl middot/cm/sup 2/ were measured using Kelvin test structures.

What is involved in creating learning environments for the 21st century? How can school facilities serve as tools for teaching and meet the needs of students in the future? What components are required to design effective schools, and how does architecture relate to the purposes of schooling? These are some of the questions addressed at the seminar on "Creating 21st Century Learning Environments" organised by the United Kingdom’s Department for Education and Skills and the OECD Programme on Educational Building (PEB). The answers provided by four people with first-hand experience in building schools are summarised here. A development and management professional explains how the school building can serve as a three-dimensional learning tool. A school principal describes how his recently-built public school in New Zealand was designed to meet the learning needs of 21st century students. A building planner presents what he considers the essential components for developing effective facilities for tomorrow, supported by his own experience in planning schools. Finally, the director of an architectural firm defines the common purposes of secondary schooling and their relation to design.

Qu’implique la creation d’environnements d’apprentissage pour le XXIe siecle ? Comment les installations scolaires peuvent-elles servir d’outils pedagogiques et repondre aux besoins des eleves dans le futur ? Quels elements sont necessaires pour concevoir des etablissements efficaces et comment l’architecture reflete-t-elle les besoins educatifs ? Ce sont la quelques-unes des questions qui ont ete traitees pendant le seminaire sur le theme « Concevoir les environnements d’apprentissage du XXIe siecle » organise par le ministere britannique de l’Education et des Competences (DfES) et le Programme de l’OCDE pour la construction et l’equipement de l’education (PEB). Les reponses a ces questions, apportees par quatre experts de la construction de bâtiments scolaires, sont resumees ci-apres. Un professionnel en conception et gestion explique comment un bâtiment scolaire peut servir d’outil pedagogique tridimensionnel. Un directeur d’etablissement public en Nouvelle-Zelande decrit la facon dont son ecole recemment construite a ete concue pour repondre aux besoins pedagogiques des eleves du XXIe siecle. Un specialiste en planification de la construction presente ce qu’il considere comme des elements essentiels a la conception d’installations efficaces pour le futur, en s’appuyant sur sa propre experience en matiere de planification d’etablissements scolaires. Enfin, le directeur d’un cabinet d’architectes definit les objectifs de l’enseignement secondaire et leur lien avec la conception.

Background To interface neurons with silicon semiconductors is a bioengineering challenge. Such constructs provide a platform for understanding neuronal coding and learning, an arena for modelling disease, and ultimately a step towards creating intelligent neuroprostheses. A prerequisite is the ability to dictate the spatial organisation of neuronal cells, in a context in which electrical and synaptic behaviour can be assessed. Our aim was to pattern cells on silicon, leading the way to the eventual incorporation of a wide range of biomicroelectromechanical systems for cellular interrogation. Methods A predetermined design of the chlorine-containing polmer parylene-C was photolithographically printed onto oxidised silicon wafers (in a microelectronics cleanroom facility). Parylene-patterned chips were activated by acid etching and then incubated in fetal calf serum. The resulting substrate became differentially cell-adhesive (parylene) or repulsive (SiO2) for certain cell types. A human glioma-derived stem-like cell line that had been isolated during debulking surgery was cultured on-chip, growing selectively on parylene. Neurons (Lund Human Mesencephalic [LUHMES] cell line) were then plated, adhering to the glial template and extending neurites to connect with adjacent cells to form a network. The effect of parylene design on neuronal network configuration was assessed by use of a pattern of circular nodes with four orthogonal spokes printed in arrays of three different configurations (node diameter 50 μm, spoke length 125 μm; node 100 μm, spoke 100 μm; node 250 μm, spoke 100 μm). Findings Ten different cell lines were assessed on the parylene–silicon cell-patterning platform. Cell adhesion behaviour was heterogeneous, with only select cell lines patterning at high resolution. LUHMES neurons in isolation failed to pattern. However, in co-culture with glioma-derived stem-like cells (which pattern accurately), the neurons adhered and differentiated to form networks. Neurite directionality differed significantly according to parylene design (Kolmogorov-Smirnov 250 μm vs 100 μm nodes D=0·204, p=0·001; 100 μm vs 50 μm nodes D=0·147, p=0·028), allowing creation of reticular neuronal networks. Interpretation The cell adhesion molecule profile of different cell lines affects their behaviour on the parylene–silicon platform. By consolidating DNA microarray data from cell types with contrasting patterning behaviour, we hope to correlate gene expression profiles with a cell's tendency to adhere to, or be repulsed by, the two contrasting substrates. The co-culture approach we describe has allowed creation of defined neuronal networks on silicon. The next steps include assessing long-term viability and functionality of patterned networks, while also improving control over their spatial organisation. Funding Wellcome Trust.

Cell patterning commonly employs photolithographic methods for the micro fabrication of structures on silicon chips. These require expensive photo-mask development and complex photolithographic processing. Laser based patterning of cells has been studied in vitro and laser ablation of polymers is an active area of research promising high aspect ratios. This paper disseminates how 800 nm femtosecond infrared (IR) laser radiation can be successfully used to perform laser ablative micromachining of parylene-C on SiO2 substrates for the patterning of human hNT astrocytes (derived from the human teratocarcinoma cell line (hNT)) whilst 248 nm nanosecond ultra-violet laser radiation produces photo-oxidization of the parylene-C and destroys cell patterning. In this work, we report the laser ablation methods used and the ablation characteristics of parylene-C for IR pulse fluences. Results follow that support the validity of using IR laser ablative micromachining for patterning human hNT astrocytes cells. We disseminate the variation in yield of patterned hNT astrocytes on parylene-C with laser pulse spacing, pulse number, pulse fluence and parylene-C strip width. The findings demonstrate how laser ablative micromachining of parylene-C on SiO2 substrates can offer an accessible alternative for rapid prototyping, high yield cell patterning with broad application to multi-electrode arrays, cellular micro-arrays and microfluidics.

The integration of p-channel metal-oxide-semiconductor transistors and tantalum bridge structures for the fabrication of resonant gate transistors (RGTs) that operate in the audible frequency range has been developed. Resonant gate transistors with channel length of 15 μm and clamped-clamped tantalum bridges of 0.5 mm to 1.6 mm in length have been fabricated. The measured first modal frequency of the bridges has been found to be higher than the expected theoretical value. From the experimental and theoretical analysis of the first three modes, the stress in the bridges has been extracted and found to be tensile with values of 3 MPa – 10 MPa. Finite element simulation has validated the extracted stress and the mode shapes of the tantalum bridges. The modulation of conductance in the channel region between the source and drain by the tantalum bridge of the RGT has been demonstrated. The threshold voltage and transconductance of the fabricated p-channel RGT have been measured to be −37 V and 6.84 μS, respect...

Silicon carbide cantilever beam resonators have been designed with top electrodes made of piezoelectric lead zirconium titanate (PZT). The devices have been simulated, fabricated, and tested. Piezoelectric actuation has been performed by applying an alternating actuation voltage to the PZT electrodes, thus inducing vertical displacements. The devices have been fabricated with a beam length of 150 and 200 μm, and driven into resonance at frequencies in the kilohertz range. The devices’ resonance has been detected by monitoring the impedance of the actuating electrode. Simulations and measurements have shown that the electrode length on top of the beam influences the magnitude of the deflection and the resonant frequency of the devices. Furthermore, the electrical feedthrough capacitance presented by the piezoelectric electrode has been observed to strongly influence the output impedance of the resonators. The obtained results show the importance of the electrode design for the optimization of the performan...

This paper discusses the main issues associated with integrating electrode controlled droplet motion using electro wetting on dielectric (EWOD) with IC foundry technology. The motivation behind this approach is based upon the desire to increase the number of control electrodes, which requires the implementation of on-chip line-column microelectronics. Increasing the number of electrodes is attractive as it provides the opportunity to finely adjust droplet size, and also increases the number of droplets that can be individually moved simultaneously. The tradeoffs associated with minimising the drive voltage by appropriate choice of dielectric thickness, strength and permittivity, are discussed and examples presented of systems with the ability to move liquid droplets using voltages between 27 and 70V. A small electrode array has been designed using transistors with high voltage shields using a 100V CMOS process. This circuitry has been fabricated and can successfully apply 90V to the electrodes. The paper presents the considerations related to the chip design and the issues associated with EWOD post-processing and the microfluidic packaging requirements.

As silicon integrated circuits (ICs) continue their development scaling to smaller geometries there are increasing signs that the industry is diversifying into new device types and associated new application areas. The mainstream IC industry which is manufacturing devices such as memories and microprocessors will be following the ITRS roadmap towards smaller and smaller devices. However, in parallel, there will be an increasing activity involving the integration of silicon with other technologies and new materials, and it is clear that MEMS will form an important component of this Silicon+ activity. This paper identifies the options available for integrating MEMS with IC technology and examples will be used to identify the issues associated with their implementation through a number of examples.