This PDF file contains the front matter associated with SPIE Proceedings Volume 6589, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

As the nano-scale becomes a focus for engineering electronic, photonic, medical, and other important devices, an unprecedented role for biomolecules is emerging to address one of the most formidable problems in nano-manufacturing: precise manipulation and organization of matter on the nano-scale. Biomolecules are a solution to this problem because they themselves are nanoscale particles with intrinsic properties that allow them to precisely self-assemble and self-organize into the amazing diversity of structures observed in nature. Indeed, there is ample evidence that the combination of molecular recognition and self-assembly combined with mutation, selection, and replication have the potential to create structures that could truly revolutionize manufacturing processes in many sectors of industry. Genetically engineered biomolecules are already being used to make the next generation of nano-scale templates, nano-detailed masks, and molecular scaffolds for the future manufacturing of electronic devices, medical diagnostic tools, and chemical engineering interfaces. Here we present an example of this type of technology by showing how a protein can be genetically modified to form a new structure and coated with metal to lead the way to producing "nano-wires," which may ultimately become the basis for self-assembled circuitry.

Fabrication and characterization of a passive silicon microfabricated direct methanol fuel cell (&mgr;DMFC) are reported. The main characteristics of the device are its capability to work without complex pumping systems, only by capillary pressure, and the fact that its performance is not affected by the device orientation. A simple fabrication process, based in DRIE (Deep Reactive Ion Etching), allows obtaining a reliable and low-cost final device. The device consists of two silicon microfabricated plates mounted together with a commercial membrane electrode assembly (MEA). Current-voltage (I-V) and current-power (I-P) curves of the device at different methanol concentration, orientation and geometric variation of silicon plates are presented. Optimal performance was obtained with a methanol concentration of 3M, that yielded a maximum power density of 10.5 mW/cm². The results obtained in this work demonstrate the feasibility of the device and give a guideline for design and conditions optimization.

This paper describes asynchronous MAC (Medium Access Control) strategies based on the IEEE 802.15.4 physical layer for wireless aeronautical applications where low power and low latency are important requirements as well as security and data integrity. Sensor data is acquired and collected on request, by means of a mobile device, and later stored in a centralized database. In order to have the smallest power consumption the wireless sensor has to remain in deep sleep mode as long as possible and wake up and listen periodically for RF activity. If its unique ID is mentioned in the destination address field, the complete frame is received, processed and replied if necessary. If the detected packet is addressed to another sensor the reception will stop immediately and the wireless sensor will go into deep sleep mode again. Listening instead of sending actively does not 'pollute' the already crowded 2.45GHz spectrum, reduces collisions and increases security. The mobile data concentrator can not be synchronized with all the sensors installed in a distributed environment, therefore smart asynchronous data transmission strategies are needed to reduce latencies and increase throughput. For the considered application, sensors are independent of each other, simply share the medium and together with the data concentrator are organized in a star network topology. The centre of the star is the concentrator which is rarely in range. It coordinates and activates the wireless sensor nodes to collect the measured data.

This work describes the design and implementation of a resonator structure for the fabrication of an electromagnetic inertial microgenerator for energy scavenging from ambient vibrations. This structure is based in the use of a permanent magnet (inertial mass) mounted onto a polymeric membrane. ANSYS simulations are carried out to investigate the influence of the membrane geometry on the resonant frequency. Moreover, generator prototypes have been fabricated with a modular manufacturing process in which the electromagnetic converter and the mechanical resonator are manufactured separately, diced and then assembled. In these prototypes, the influence of the resonator geometry (membrane dimensions) on the generator behaviour has been investigated. The experimental results show the ability of these devices to generate power levels in the range of μW's and output voltages in the range of hundreds of mV. The parasitic damping of the resonator structures is estimated from the fitting of the experimental data, and suggests the existence of an intrinsic limitation of the polymers related to spring stiffening effects at large excitation amplitudes.

Microelectromechanical systems (MEMS) have found several applications in various fields from homeland security to personalized health care. However, rendering MEMS into autonomous wireless systems operating in any given environment requires the integration of energy harvesters into the MEMS structures, ensuring thus the self-powering of the devices. In this work, we investigated the mechanical and magnetic properties of Samarium Cobalt (SmCo) thin films, with the goal to implement them into electromagnetic energy harvesters. The films were deposited by sputtering on suspended silicon cantilevers fabricated with a front-side micromachining process. The magnetic films, grown under various pressures and thermally annealed at several temperatures and ambient conditions, were studied in terms of their mechanical and magnetic properties. Depending on the fabrication parameters, the stresses that developed in the magnetic material, deposited on top of the cantilevers, are altered from compressive (downward deflection of the cantilevers) to tensile (upward deflection), indicating that it is possible to control not only the magnetic properties of the films, but also the mechanical properties of the complete structure. Our results suggest that SmCo magnetic films are suitable candidates for integration in suspended structures for the development of electromagnetic micro-generators.

In various fruit storage applications precise and continuous ethylene detection is needed. The aim of this work is the development of a miniaturised mid-infrared filter spectrometer for ethylene detection at 10.6 &mgr;m wavelength. For this reason optical components and signal processing electronics were developed, tested and integrated in a compact measurement system. The present article describes the optical components, the integration of the optical system, electronics and results of gas measurements. Next to a Silicon-based macroporous IR-emitter, a miniaturised absorption cell and a detector module for the simultaneous measurement at four channels for ethylene, two interfering gases and the reference signal were integrated in the optical system. Optical filters were attached to fourfold thermopile-arrays by flip-chip- technology. Silicon-based Fresnel multilenses were processed and attached to the cap of the detector housing. Because of the high reflection losses at the silicon-air surface the Fresnel lenses were coated with Antireflection layers made of Zinc sulphide. For the signal processing electronics a preamplification stage and a Lock-in-board has been developed. First ethylene measurements with the optical system with miniaturised gas cell, Silicon-based IR-emitter, a commercial thermopile detector and the self-developed system electronics showed a detection limit of smaller than 20ppm.

Vertical-cavity surface-emitting lasers (VCSELs) are used for oxygen monitoring via tunable diode laser spectroscopy at 760nm wavelength. For the desired application, novel polarization-stable laser diodes based on AlGaAs were developed. We present measurements of the pressure-broadening coefficients of the electric dipole forbidden oxygen A-Band b¹Σ^g ₊ -> X³Σ^g ₊ transition at 760nm. For the first time the pressure-broadening coefficients were determined with a temperature tuned vertical-cavity surface-emitting laser. Because of special techniques of polarization stabilization with a combination of a dielectric surface grating and a surface relief the VCSELs have a mode hop-free tuning range of more than 7nm and a sidemode suppression of more than 30dB. This provides a low cost laser diode system with a wide tuning range, which enables the possibility of simultaneous measurement of temperature, pressure and oxygen concentration in air, high pressure measurements and also a higher accuracy of oxygen concentration measurements due to averaging over 18 absorption lines.

In this paper we describe the use of thermo-activated PNIPAM nano-material in optical switching devices. In other publications, the PNIPAM is used either as a carrier for crystalline colloidal array self-assemblies or as micro-particles that serve as pigment bags. In this publication we use a simpler-to-fabricate pure PNIPAM solution in a semi-dilute regime. The PNIPAM devices produced are transparent at temperatures below a critical temperature of 32°C and become diffusing above this temperature. We show that at 632nm the transmission through the devices is about 75% in the transparent state while the additional attenuation achieved in the diffusing state is of the order of 38 dB. The experimental fall and rise times obtained are large (about 300ms and 5s respectively) due to the non-optimised thermal addressing scheme. In addition, spectral measurements taken in the infrared spectrum (700-1000nm) demonstrate that the cell response is flat over a large portion of the infrared spectrum in both the transparent and the diffusing states.

Dye based solar cells have been studied thoroughly in recent years. However, using this technology for dye based light sensors in polymer based systems offers several advantages compared to classical devices. A printable light sensor could be easily integrated into current smart label fabrication processes. Moreover, printable light sensors combined with novel conductive polymers could solve reliability issues resulting from bonding processes. In this paper we report on the fabrication of dye based light sensors using Ruthenium 535-bis-TBA as active dye and Iodide solution as charge transporting layer. A prototype has been developed and tested successfully. In order to improve the technology towards smart label integration, silica gel has been used to harden the Iodide liquid electrolyte. Depending on the silica gel concentrations, different stiffness levels can be achieved. Whereas the first light sensor prototypes have been made on glass substrates, the new ones are based on polymer substrates. The polymer foil KAPTON by Du Pont has been used as substrate. Special care has to be taken regarding the preparation of the transparent electrodes. The transparent conductive oxide (TCO) Indium Tin Oxide (ITO), which has been used as transparent electrode, has to be cured at elevated temperatures. In conclusion we have shown that dye based light sensors can be used for the integration into smart labels. Moreover modifications in the process lead to a light sensor which is compatible to future polymer based systems.

Recently, miniaturized devices and microstructures made from Low Temperature Cofired Ceramics (LTCC) are gaining increasing interest due to advantages especially on the field of a simplified wiring approach. This is in particular true when applications are targeted for theses devices where harsh environmental conditions are present, such as high temperatures, aggressive media or high system-related pressure levels. In this paper an overview is given on some selected devices for automotive and airborne applications designed for such challenging system constraints. For an enhanced performance of these miniaturized sensor elements, basic investigations are performed on the novel use of thin film metallization on LTCC substrates which are basically designed for thick film technology.

We report the development of a high efficiency magnetic microfluidic mixer based on a novel 3D impellor-shaped ferromagnetic micro-stirrer bar. The 3D impellor-shaped micro-stirrer bar with 31.6º inclined angle is fabricated using titled (55º) SU-8 exposure technique. The 3-D inclined micro-stirrer bar causes 3-D perturbation of fluids resulting in rapid mixing in microscale. When compared with a vertical straight sidewall micro-stirrer bar, approximately 20% of mixing efficiency enhancement is achieved.

This work presents the realization of a MEMS-based miniaturized system for liquid chromatography focused on agrofood applications, and in particular on the detection of wine defects. The main modules of the systems are: i.) a Si-based separation column with inlet/outlet for fluidic connections; ii.) a three-microelectrode voltammetric sensor. Moreover, a Platinum heater has been realized on the back side of the chip containing the Si column in order to operate at temperatures greater than the room temperature. The realized device consists of a Silicon/Pyrex structure realised by anodic bonding. Microchannels and inlet/outlet have been fabricated by Deep Reactive Ion Etching (DRIE) and Tetra Methyl Ammonium Hydroxide (TMAH) wet etching respectively. The column has been functionalised with n-octyltriethoxysilane (C8-TEOS). A lift-off technique has been developed for realizing the Pt heater and the Pt microelectrodes on-chip. In order to separately characterize the main modules of the device, a package of the system has been realized following a modular approach; appropriate tubing and nanovolume connections have been used in order to minimize dead volumes. Then other packages approaches have been considered in order to minimize dead volumes and to avoid leakage issues. Preliminary characterization tests of the two main modules have been performed. The capability of the system to correctly retain and detect Acetic acid has been tested.

A microfluidic system is presented that enables in-vitro investigations on tumor cells under conditions similar to those in a blood vessel. Microscopic test objects are immersed in a liquid that circulates in a closed-loop PDMS microchannel and that is sandwiched between a glass and a LiNbO₃ wafer which are both transparent to enable visual access. The actuation is achieved electroacoustically by interdigital transducers on the LiNbO₃ wafer generating a Rayleigh-type surface acoustic wave that transfers momentum to the liquid. The envisaged medical application for this chamber is briefly sketched, its design and fabrication are discussed, and the operability is demonstrated.

The MEDEA+ SWANS (Silicon Platform for Wireless Advanced Networks of Sensors) project aims at defining a generic silicon platform, integrating analogue and digital Intellectual Property (IP) blocks for wireless sensor nodes technology. This generic platform will be used in various applications, such as transportation (aeronautics, automotive), homeland security, environmental and health/fitness. In the aeronautical application, the platform monitors, continuously, aircraft structures to detect whether a crack exists or not and process the data in real time, inside the platform. Measurements are provided by an inductive sensor glued on a structure and are acquired during flights. The sensor impedance (real and imaginary parts) varies depending on the state of the part area on which it is stuck. For example, this sensor aims at monitoring the further evolution of the crack too. The data are transmitted from the sensor to an ARM microcontroller through an electronic conditioner. Then, they are analysed and stored in a non volatile memory. Data measurements are collected by a RF transmission, every 2 or 4 months. A 3D stack platform demonstrator that allows the use of different technologies, will be realised, fully tested and characterised.

This paper describes the design of a novel low-power single-axis fluxgate sensor. Several soft magnetic alloy materials have been considered and the choice was based on the balance between maximum permeability and minimum saturation flux density values. The sensor has been modelled using the Finite Integration Theory (FIT) method. The sensor was imposed to a custom macroscale optimisation technique that significantly reduced the power consumption by a factor of 16. The results of the sensor's optimisation technique will be used, subsequently, in the development of a cutting-edge ground based magnetometer for the study of the complex solar wind-magnetospheric-ionospheric system.

To ensure an enhanced life-time of micromachined devices, passivation layers are commonly applied to protect functionalized components against environmental stress. For flow sensitive elements on a flexible polyimide foil the use of reactively sputter-deposited aluminium oxide is investigated. Due to a high defect density located at the interface between the passivation layer and the organic substrate, the adhesion of the pure aluminium oxide thin films on the organic substrate was found to be poor when applying a combination of mechanical and thermal treatment as an accelerated ageing procedure. A bi-layer consisting of aluminium nitride and aluminium oxide is proposed to enhance the low adhesion capability being strongly disadvantageous for any technical application.

This paper is presenting a robust gyroscope sensor with an electrical and mechanical self-test option and the ability to suppress the quadrature error. The presented sensor is based on a tuning-fork working principle. The mechanical part is assembled in bulk-technology produced with a wet etching process. The two detection elements are manufactured with a standard CMOS-process and the material of the two thin-film actuators is AlN (aluminium-nitrid). The two actuators can be controlled independently from each other. Two electronic PCB's were developed for actuating and measurement. One is including the analogue signal path; the second PCB is the digital electronics consisting of a FPGA and other peripherals. The tuning fork is actuated in a primary oscillation mode also called drive mode. For keeping the oscillation in resonance, a digital PLL is used in a forced feedback loop. To have a constant energy in the drive mode an Amplitude-Gain-Control (AGC) is implemented. An appearing angular rate causes the corriolis-force which is actuating secondary oscillation, also called detection mode. The amplitude of this oscillation is proportional to the angular rate. The signal has a component resulting from the mechanical imbalance. To separate these two signal parts from each other a synchronous demodulator followed by a digital filter chain has been developed. To achieve the maximum suppression of the imbalance signal a control-loop is used to shift the phases of the two actuation signals. This creates an additional force that compensates the movement as a result of the mechanical imbalance. With the implementation of this control loop the performance of the sensor was increased. An enhanced temperature stability over operation was achieved with the means of this compensation.

A new tactile sensor with piezoresistive read-out is presented. The sensor is designed for measurements of high aspect ratio structures with a resolution of some ten nanometer and a measuring range of hundreds of micrometer. Possible applications of the sensor are suggested. The silicon micromachining fabrication process is shown in detail next to the finite element simulations we performed. First measurements and a calibration process are described and the results are shown. The implementation into a measuring system is indicated.

A microelectromechanical torsional oscillator was used to obtain new constraints in the search for new Yukawa-like interactions at the ~ 100 nm range. A new heterodyne technique was used to enhance the possible contributions of hypothetical forces, while electromagnetic interactions (including the ones associated with vacuum fluctuations), remained the same. In particular, the force between a Au-coated sphere and a Au film deposited on the oscillator was subtracted in situ from the force between the same sphere and a composite film made out of Ge and Au. The combination of the high quality factor Q of the oscillator and this new approach that greatly reduced the Casimir background yielded improvements in the constraints close to one order of magnitude over the 50-400 nm interaction range.

This paper reports a deep study of the frequency response of ZnO-based piezoelectric cantilevers. Laser vibrometry and impedance measurements have been carried out on such devices, obtaining a good agreement in the characteristic frequencies. However, certain resonances that are clearly identified thanks to the high sensitivity of the laser vibrometer do not show the corresponding impedance change. A computational model has been successfully developed to allow us to explain this behaviour based on the piezoelectric charge generated by the different modes. Finally, we discuss the essential role played by the modal shapes in the electrical detection of the resonances.

A piezoresistive silicon cantilever-type tactile sensor was described as well as its application for dimensional metrology with micro components and as a transferable force standard in the micro-to-nano Newton range. As an example for tactile probing metrology the novel cantilever sensor was used for surface scanning with calibrated groove and roughness artifacts. Force metrology was addressed based on calibration procedures which were developed for commercial stylus instruments as well as for glass pipettes designed for the characterization of the vital forces of isolated cells.

The electronic feedback used with microcantilevers (&mgr;CLs) to obtain their best performances requires a precise driving method to exert on them a force proportional to an electrical signal. One of these methods is Electrostatic Driving (ED) easily achieved on &mgr;CLs placed some mm apart from a conductive surface. This easy appearance of ED is the reason to find it unexpectedly, coming from electrical fields not properly shielded, in setups designed for other driving as Magnetic Driving (MD). When feedback loops designed for MD suffers from this ED contamination due to an unshielded solenoid for example, the tight phase control of the driving is lost. As a result, self-oscillation of the loop does not take place at f₀, the resonance frequency of the &mgr;CL, or an appealing shift in the resonance frequency from f₀ without feedback to f_FB=f₀±&Dgr;f with feedback appears in non-oscillating loops. A feedback force proportional to the displacement (DF) or to the speed (SF) of &mgr;CLs has been studied and it is demonstrated that SF sets an apparent temperature for the thermal motion of a &mgr;CL without changing its native f₀ (a desired feature for high stability &mgr;CL-based oscillating sensors) whereas the f_FB±f₀ produced by DF allows an electrical tuning of f_FB very useful for &mgr;CL-based Voltage Controlled Oscillators.

The aim of this paper is to present an integrated process flow for a smart tag with integrated sensors and RFID communication, a Flexible Tag Microlab (FTM). The heart of the designed container tracing system is an RFID system (Reader + Tag) with gas sensing capabilities on board. In the former prototypes, the chemical sensors were integrated on the reader, whereas the tags where addressed like conventional RFID-tags containing also physical (temperature, humidity and light) sensors. However, this paper will show how the gas sensing reader functionalities are being transferred to the tag, reaching a flexible tag microlab, which represents a real innovation in the field of flexible labels. Key issues for the realisation of the FTM, such us flexible substrates and gas sensor integration technologies will be presented. The process flow employed for the two metal levels interconnect fabrication will be described in detail. The material used is the DuPont^TM Pyralux^(R) AP 8525R double-sided copper-clad laminate, formed by a Kapton foil with a copper layer on each side. The vias and windows openings are performed by femtosecond laser ablation. The copper interconnections are realized by photolithography and wet chemical etching. The MOX sensors hotplates specially developed to fulfil the FTM constrains in terms of low power consumption has been used to prove two integration technologies into the flexible substrates: Chip on Flex (COF) wire bonding and Anisotropic Conductive Adhesive (ACA) flip chip bonding. Both technologies will be compared and benchmarked for future product developments.

A multisensing flexible Tag microlab (FTM) with RFID communication capabilities and integrated physical and chemical sensors for logistic datalogging applications is being developed. For this very specific scenario, several constraints must be considered: power consumption must be limited for long-term operation, reliable ISO compliant RFID communication must be implemented, and special encapsulation issues must be faced for reliable sensor integration. In this work, the developments on application specific electronic interfaces and on ultra-low-power MOX gas sensors in the framework of the GoodFood FP6 Integrated Project will be reported. The electronics for sensor control and readout as well as for RFID communication are based on an ultra-low-power MSP430 microcontroller from Texas Instruments together with a custom RFID front-end based on analog circuitry and a CPLD digital device, and are designed to guarantee a passive ISO15693 compliant RFID communication in a range up to 6 cm. A thin film battery for sensor operation is included, allowing data acquisition and storage when no reader field is present. This design allows the user to access both the traceability and sensor information even when the on-board battery is exhausted. The physical sensors for light, temperature and humidity are commercially available devices, while for chemical gas sensing innovative MOX sensors are developed, based on ultra-low-power micromachined hotplate arrays specifically designed for flexible Tag integration purposes. A single MOX sensor requires only 8.9 mW for continuous operation, while temperature modulation and discontinuous sensor operation modes are implemented to further reduce the overall power consumption. The development of the custom control and RFID electronics, together with innovative ultra-low-power MOX sensor arrays with flexible circuit encapsulation techniques will be reported in this work.

The reliable and low-cost quantitative detection of ethylene for food/fruit applications remains an unsolved problem. Existing commercial systems are able to quantify ethylene (at sub ppm levels) but either they are off-line: require periodic sample collection and use of reagents or high-cost. We will report on the development of an RFID reader with onboard micro-machined metal oxide gas sensors aimed at monitoring climacteric fruit during transport and vending. The developed platform integrates a commercial off the shelf inductive coupling RF transceiver in the 13.56MHz band, fully compliant with the ISO15693 standard, micro-hotplate gas sensors, driving and readout electronics. If the sensors are operated at a fixed temperature, the reader could work as an alarm level monitor able to assess the conservation stage of apples. On the other hand, when the sensors are operated under an optimised temperature-modulation mode, accurate calibration models for the species that are relevant to assess the conservation stage of apples (i.e., ethylene, acetaldehyde and ethanol) can be built. Finally, different feature extraction techniques such as the FFT and the Energy Vector will be used in combination with pattern recognition tools like PLS and PLS-DA to show that our system is able to identify and quantify the species that are relevant for the application considered.

A new technology of flexible all-plastic pressure sensors is developed using conducting polymers as electroactive materials on plastic substrates. The lithography of one of the conducting sheets being part of the device makes feasible the construction of a distributed pressure sensor giving not only the cuantitative pressure information but also its spatial distribution. A response time as low as 2 milliseconds, and a lifetime over 1 millions of actuations are obtained. The first demonstrator works in pressure ranges from 3 to 14 Kg/cm². These working pressure ranges can be adjusted by the proper spatial design of conducting and non-conducting paths. The present paper describes the development of an innovative, low cost and flexible technology opening interesting potential opportunities for high-surface applications.

We review the fabrication process of a recently introduced phase only MEMS based spatial light modulators for maskless lithography. A brief description of this device is presented. The physical properties of its structural layers and the difficulties encountered during its fabrication process are described in detail.

Manufacturing and integration of MEMS devices by wafer bonding often lead to problems generated by thermal properties of materials. These include alignment shifts, substrate warping and thin film stress. By limiting the thermal processing temperatures, thermal expansion differences between materials can be minimized in order to achieve stress-free, aligned substrates without warpage. Achieving wafer level bonding at low temperature employs a little magic and requires new technology development. The cornerstone of low temperature bonding is plasma activation. The plasma is chosen to compliment existing interface conditions and can result in conductive or insulating interfaces. A wide range of materials including semiconductors, glasses, quartz and even plastics respond favorably to plasma activated bonding. The annealing temperatures required to create permanent bonds are typically ranging from room temperature to 400°C for process times ranging from 15-30 minutes and up to 2-3 hours. This new technique enables integration of various materials combinations coming from separate production lines.

Aluminium nitride (AlN) reactively sputter deposited from an aluminium target is an interesting compound material due to its CMOS compatible fabrication process and its piezoelectric properties. For the implementation in micromachined sensors and actuators an appropriate patterning technique is needed to form AlN-based elements. Therefore, the influence of different sputtering conditions on the vertical etch rate of AlN thin films with a typical thickness of 600 nm in phosphoric acid (H₃PO₄) is investigated. Under comparable conditions, such as temperature and concentration of the etchant, thin films with a high c-axis orientation are etched substantially slower compared to films with a low degree of orientation. When a high c-axis orientation is present detailed analyses of the etched topologies reveal surface characteristics with a low porosity and hence, low roughness values. From temperature dependant etching experiments an activation energy of 800 (± 30) meV is determined showing a reaction-controlled etching regime independent of sputter deposition conditions.

In this paper, capacitive RF-MEMS switches topologies are investigated regarding their power handling capabilities. The topologies differ from the ability to handle thermal stress by an optimization of their anchorage arms. A specific meander arms design leads in fact to enhance by a decade the flexibility regarding their thermal expansion. To evaluate the proposed RF-MEMS morphology, a specific thermal stress protocol has been defined and applied from 20°C up to 120°C. The monitoring of air gap, actuation voltage and insertion losses has been performed after each thermal stress in order to check the impact of the temperature on working switch. The main result indicates that a different thermal behavior depending on the MEMS anchorage arms morphology has been obtained.

In this paper, we present the design, fabrication and characterization of an inductively-coupled miniaturized RFID transponder using MEMS technology. The micromachined miniaturized transponder consists of a small solenoid inductor with a high permeability magnetic core, a chip capacitor and a RFID chip. They are integrated onto a micromachined SU-8 polymer substrate and it is operated in the frequency range of 13.56 to 27 MHz. Induced voltages of up to 4 V were obtained with a miniaturized 500 nH transponder coil from a 2.2 μH reader coil at 5 mm distance based on a resonant magnetic coupling mechanism. The assembled transponder was tested using a commercial RFID reader at 13.56 MHz and successful communication was established at a distance of 10 mm.

This paper introduces the use of germanium as resistive material in RF MicroElectroMechanical (MEMS) devices. Integrated resistors are indeed highly required into RF MEMS switches, in order to prevent any RF signal leakage in the bias lines and also to be compatible with ICs. Germanium material presents strong advantages compared to others. It is widely used in microtechnologies, notably as an important semi-conductor in SiGe transistors as well as sacrificial or structural layers and also mask layer in various processes (Si micromachining especially). But it also presents a great electrical characteristic with a very high resistivity value. This property is particularly interesting for the elaboration of integrated resistors for RF components as it assures miniaturised resistors in total agreement with electromagnetic requirements. Its compatibility as resistive material in MEMS has been carried out. Its integration in the entire MEMS process has been fruitfully achieved and led to the successful demonstration and validation of integrated Ge resistors into serial RF MEMS variable capacitors, without any RF perturbations.

A MEMS switch for radio frequency applications has been designed, fabricated, and characterized. The focus has been in the optimization of switch performance towards handset applications. The realized switch has actuation voltage less than 15 V for realizing a good metal-to-metal contact. Measured results show loss less than 0.25 dB up to 10 GHz with matching better than -30 dB in the down-state, and isolation better than -20 dB up to 6 GHz in the up-state.

We developed a novel method to detect the presence of unburned diesel fuel in used diesel fuel engine oil. The method is based on the use of an array of different gas microsensors based on metal oxide thin films deposited by sol-gel technique on Si substrates. The sensor array, exposed to the volatile chemical species of different diesel fuel engine oil samples contaminated in different percentages by diesel fuel, resulted to be appreciable sensitive to them. Principal Component Analysis (PCA) and Self-Organizing Map (SOM) applied to the sensor response data-set gave a first proof of the sensor array ability to discriminate among the different diesel fuel diluted lubricating oils. Moreover, in order to get information about the headspace composition of the diesel fuel-contaminated engine oils used for gas-sensing tests, we analyzed the engine oil samples by Static Headspace Solid Phase Micro Extraction/Gas Chromatograph/Mass Spectrometer (SHS-SPME/ GC/MS).

Functional metal oxide micro and nanostructures for the detection of gas are a very promising candidate for future gas-sensors. Due to reduced size and thus an increased surface to volume ratio nanosized sensitive structures offer a high potential for increasing sensitivity. A top down sputtering approach for gas sensors with nano-sized gas sensitive metal oxide areas is presented. Oxidised silicon wafer were used as substrates. The silicon dioxide film of 1 &mgr;m thickness was prepared by thermal oxidation in order to insulate the gas sensing elements from the substrate. At the sensor chips (1.5 x 1.5 mm²) a Ta/Pt film (20/200 nm thickness) was deposited and patterned to act as interdigital electrodes, heater and temperature sensor. In a second step nano-scaled tin oxide layers (60nm thick, 5 &mgr;m width) were deposited by sputtering techniques and photolithographical pattering between the platinum micro-electrodes (4 &mgr;m gap). As the last step the width of the stripes was reduced by using Focused Ion Beam (FIB) technology to obtain the desired size and structure. This enables the control of the dimensions of the structures down to the resolution limit of the FIB-system which is a few tens of nm. The structural and electrical characterisation of the sensors and their responses during exposure to several test gases including O₂, CO, NO₂ and H₂O are presented as well.

A cheap nanofabrication process for Titania (TiO₂) polycristalline nanowire array for gas sensing applications with lateral size ranging from 90 to 180 nm, and gas sensing characterizations are presented. Alternatively to typical pattern transfer techniques for submicron fabrication, authors focused on a standard 365 nm UV photolithographic process able to fabricate sol-gel nanostructured titania nanowires from a solid thin film. Main aim of present work is the experimental validation of enhanced gas sensing response of nanopatterned metal oxide thin film sensors. Two different kind of gas sensor with nanopatterned sensitive area have been realized onto silicon substrates and tested towards different EtOH concentrations; experimental tests have been carried out with a contemporary output signals collection from a nanowires-based gas sensor and a second device with solid sensitive film without patterning, in order to validate effects of nano-machining on sensitive material response.

Bismuth film electrodes (BiFEs) have a potential to replace toxic mercury used most frequently for determination of heavy metals (Cd, Pb, Zn) by anodic stripping voltammetry. We prepared a graphite disc electrode (0.5 mm in diameter) from a pencil-lead rod and developed a nitrogen doped diamond-like carbon (NDLC) microelectrode array consisting of 50 625 microdiscs with 3 &mgr;m in diameter and interelectrode distances of 20 &mgr;m on a highly conductive silicon substrate as a support for BiFEs. The disc graphite BiFE was used for simultaneous determination of Pb(II), Cd(II) and Zn(II) by square wave voltammetry (SWV) in an aqueous solution. We found the optimum bismuth-to-metal concentration ratio in the solution to be 20. The dependence of the stripping responses on the concentration of target metals was linear in the range from 1×10^-8 to 1.2×10^-7 mol/L. Detection limits 2.4×10^-9 mol/L for Pb(II), 2.9×10^-9 mol/L for Cd(II) and 1.2×10^-8 mol/L for Zn(II) were estimated. A bismuth-plated NDLC microelectrode array was used for Pb(II) determination by differential pulse voltammetry (DPV) in an aqueous solution. We found that the stripping current for bismuth-plated NDLC array was linear in the concentration range of Pb(II) from 2×10^-8 to 1.2×10^-7 mol/L. The detection limit 2.2×10^-8 mol/L was estimated from a calibration plot.

This work explores the radiation and ozone sensing properties of mixed oxides in the form of thin films. External effects, such as radiation and ozone, cause defects in the materials it interacts with and, consequently, it causes changes in their properties. These changes manifest themselves as the alterations in both the electrical and the optical parameters, which are being measured and employed for dosimetry sensor development. An Edwards E306A thermal coating system was used for In₂O₃:ZnO:SnO₂ (90% : 5% : 5%) films deposition. For the electrical properties measurements, Cu electrodes were manufactured on the glass substrate via thermal evaporation of Cu; then AZ5214 photoresist was spin-coated over it and exposed to UV light via the acetate, containing the desired electrodes patterns. After the exposure, the substrate was placed in Electrolube PDN250ML developer solution and then rinsed in water and placed in the etching solution of SEMO 3207 fine etch crystals to reveal the electrode pattern. The optical properties of In₂O₃:ZnO:SnO₂ thin films were explored using CARY 1E UV-Visible Spectrophotometer. The values of the optical band gap E_opt are estimated in the view of the Mott and Davis' theory. It was noted that E_opt decreases with the increase in radiation dose, i.e. the overall disorder of the system is increased. Doping of In₂O₃ with 5% ZnO and 5% SnO₂ dramatically changes the overall structure of the film and thus affected its sensing to gamma radiation and ozone. Mixing metal oxides in certain proportions provides a tool for controlling the sensors response.

The gas sensor based on carbon nanotubes are presently receiving considerable attention because of the outstanding properties, such as faster response, higher sensitivity, lower operating temperature and robustness of the nanotubes in comparison with the other types of sensing materials. In the present research, we demonstrate detection of hydrogen at room temperature using a Quartz Crystal Nano-balance (QCN) and as sensing material, Single-Walled Carbon Nanotubes (SWCNTs) dispersed in a polythiophene matrix. The experimental determination of H₂ in H₂/N₂ mixtures has been performed by using a counter frequency and observing the frequency shifts induced in a quartz crystal resonator by H₂ adsorption and consequent mass variation of the active layer deposited on the quartz. The high sensitivity of the realized nano-balance allows us to observe mass variations up to few nanograms /Hertz and to detect up to 1% of H₂. The good sensing performances of the nanotube-based material make unnecessary the use of any catalyst species for H₂ detection. Moreover this QCN device is able to work with good efficiency at 23 °C and 1 Atm.

This work describes the design, simulation, fabrication and characterization of a TiN/Pt microheater prepared on GaAs micromechanical structure as a prospective device for MEMS gas sensor array. We use the electro-thermal simulation to verify the properties of the designed microstructure, which conformed achievement of the operating temperatures in the range of 200 to 320°C with heating power less than 25 mW. The average temperature gradient in the active area does not exceed 0.6 K/μm. We demonstrated the fabrication of GaAs suspended membranes, realized in two steps, by combination of surface and bulk micromachining. We also describe the development and characterization of a microheater on a GaAs membrane. The power consumption at an operating temperature of approximately 550 K is about 30 mW and the achieved thermal resistance value is 8.43 K/mW.

Due to the demand for accurate, reliable and highly sensitive pH sensors, research is being pursued to find novel materials to achieve this goal. Semiconducting metal oxides, such as TiO, SnO and SnO₂ and insulating oxides such as Nb₂O₅ and Bi₂O₃, and their mixtures in different proportions are being investigated for this purpose. The films of these materials mixtures are used in conjunction with an interdigitated electrode pattern to produce a conductimetric/capacitive pH sensor. The advantages of this approach include straightforward manufacturing, versatility and cost-effectiveness. It was noted that upon contact with a solution, the electrical parameters of the films, such as resistance etc., change. The correlation of these changes with pH values is the basis for the proposed system development. The ultimate goal is to find materials composition, which would have the highest sensitivity towards the pH level of the solutions. It was found that the materials that produced the highest sensitivity either had a long response time or were unstable over a wide pH range. Those exhibiting lower sensitivities were found to be more stable over a wide pH range. All oxide films tested demonstrated a change in electrical parameters upon contact with buffers of known pH value.

The development of an integrated gas chromatographic system using micro and nanotechnologies is presented in this paper. For this purpose, the different components of the chromatographic system, namely the preconcentrator, the chromatographic column and the gas sensors are being investigated and developed, and the actual state of this investigation is presented. The proposed target application comes from the agrofood industry, in particular the determination of the fish freshness. The structure of the preconcentrator has been fabricated using deep reactive ion etching (DRIE). The same fabrication technique has been employed for the patterning of the silicon microcolumns, which have been sealed with Pyrex glass. Inlet and outlets have been connected and initial experiments of functionalization have been performed. Gas sensors have been obtained by microdeposition of doped WO₃ or SnO₂ nanomaterials on microhotplates and their responses to the gases of interest have been measured, proving that the target gas concentrations can be detected.

The aim of the MicroActive project is to develop an instrument for molecular diagnostics. The instrument will first be tested for patient screening for a group of viruses causing cervical cancer. Two disposable polymer chips with reagents stored on-chip will be inserted into the instrument for each patient sample. The first chip performs sample preparation of the epithelial cervical cells while mRNA amplification and fluorescent detection takes place in the second chip. More than 10 different virus markers will be analysed in one chip. We report results on sub-functions of the amplification chip. The sample is split into smaller droplets, and the droplets move in parallel channels containing different dried reagents for the different analyses. We report experimental results on parallel droplet movement control using one external pump only, combined with hydrophobic valves. Valve burst pressures are controlled by geometry. We show droplet control using valves with burst pressures between 800 and 4500 Pa. We also monitored the re-hydration times for two necessary dried reagents. After sample insertion, uniform concentration of the reagents in the droplet was reached after respectively 60 s and 10 min. These times are acceptable for successful amplification. Finally we have shown positive amplification of HPV type 16 using dried enzymes stored in micro chambers.

A TiNi/diamond-like-carbon (DLC) microcage for biological application has been designed, fabricated and characterized. A compressively stressed DLC film with TiNi pattern on top lifts the fingers upwards once they are released from the substrate, and the microcage can be closed through shape memory effect of top TiNi film with temperature below 80°C. Further heating above 100°C, the gradual opening of the microcage can be obtained due to thermal bimorph effect. The biocompatibility of both the TiNi and DLC films has been proved using a cell-culture method.

The shape memory effect is about to become more and more important as an innovative actuation principle in micro system technologies. Shape memory alloys (SMA) are able to return into a pre-memorized shape when heated. Due to this regeneration force and actuation is produced. This publication reports on the design and the functionality of SMA micro actuators and their applications for active shape control, handling technologies and medical engineering. Thin NiTi foils have been chosen because of their well defined properties and high strength. In order to integrate them into micro systems, different manufacturing methods have been applied and improved at the Institute for Microtechnology (IMT). Laser cutting and wet chemical etching for example are used to fabricate actuator elements for several applications. Different methods for electrical and mechanical connections of the actuators are employed, for example soldering by the use of an additional gold layer. A batch fabrication process of SMA actuators is realized by embedding NiTi-elements into SU-8 structures. Three different micro actuator concepts are presented: A multi-actuator system for deformation of elastic surfaces, which is driven by numerous identical single actuators connected in parallel and in series, a micro gripper for handling and assembling of complex hybrid micro systems and a micro actuator system in medical tools for percutaneous resection of aortic valves.

In this work we investigate, for the first time, the performances of a system based on hydrogenated amorphous silicon photosensors for the detection of Ochratoxin A. The sensor is a n-type/intrinsic/p-type amorphous silicon stacked structure deposited on a glass substrate. The mycotoxin is deposited on a thin layer chromatographic plate and aligned with the sensor. An ultraviolet radiation excites the ochratoxin A, whose fluorescence produces a photocurrent in the sensor. The photocurrent value is proportional to the deposited mycotoxin quantity. An excellent linearity of the detector response over more than two orders of magnitude of ochratoxin A amount is observed. The minimum detected mycotoxin quantity is equal to 0.1ng, suggesting that the presented detection system could be a good candidate to perform rapid and analytical ochratoxin A analysis in different kind of samples.

Pulse voltammetry was employed to discriminate among different concentrations of defects in wine. The microelectrodes were fabricated as patterned platinum thin films on silicon wafers by means of silicon fabrication technology. The film pattern was as interdigitated fingers having a 2 μm fingers gap and active area of 100x100 μm²; a silicon nitride passivation permits a selective exposure of microelectrodes to electrolyte. Principal Component Analysis (PCA) of the current responses indicated that concentrations of acetaldehyde and L-ascorbic acid could be discriminated in a white wine electrolyte. Finally the capability of defects concentrations detection in two-defects solutions (acetaldehyde + L-ascorbic acid) has been investigated.

Current research work on the development of automated microrobot-based nanohandling stations (AMNSs) using the probe of an atomic force microscope (AFM) as an endeffector is presented. The manipulation of individual multiwalled carbon nanotubes (MWCNTs) and the characterization of eukaryotic cells are aspired applications. For this reason, the developed AMNSs have to be integrated both into a scanning electron microscope (SEM) for the nanomanipulation of carbon nanotubes (CNTs) and into an optical microscope for the cell characterization. Such an AMNS combines different micro- and nanomanipulators, each offering three degrees of freedom (DoF), in order to perform the coarse and fine positioning between object and endeffector. Piezoresistive AFM probes are applied as an endeffector allowing to measure the acting forces and to realize a force feedback for the station's control system. First investigations have been carried out by bending of MWCNTs and calculating the Young's modulus of a MWCNT. Electrically conductive adhesives (ECAs) have been developed for the microelectronics industry, and their mechanical properties have to be determined. Therefore an AMNS for the mechanical characterization of thin ECA coatings by nanoindentation inside an SEM is presented as well, showing first experimental results.

Electronic Tongue systems have been widely used during last decades, reaching an high level of performances in the detection and quantification of several matrices, such as for example waters, soft and alcoholic drinks. Next step in research is represented by the miniaturization of these systems: it is made possible by the integration of the knowledge on materials suitable for sensorial purpose and the silicon technology, which allows the development of micro-dimensioned sensors. In this work we report the development of a sensor array composed of 8 electro-polymerized porphyrin based membranes, with an active area exposed to liquid of 0.5 mm². The miniaturized system, integrated on a single silicon wafer and completed by read-out electronics, was firstly tested towards standard analytes and then applied on real white wine samples for the detection of some analytes mimicking wine defects, namely H₂S, SO₂ and CH₃CO₂H.

Dispersions of small catalyst particles on metal oxide sensitive layers are commonly used as catalytic activators in gassensing devices. Platinum and palladium are a well known catalyst, but their capability to increase the selectivity of metal oxide gas sensors is however far from being well understood and is thus still a matter of investigation. One recent trend is the size reduction of the catalyst particles. We present an approach to optimize the specific response to gases by using specially prepared nano-sized palladium clusters on highly dense sputtered polycrystalline SnO₂. For the deposition of the palladium clusters energetic cluster impact technique is used. Using this deposition technique, charged clusters are accelerated by an electric field of several keV and directed onto the substrate. The deposited clusters consist of 3000 palladium atoms in average, forming clusters of approx. 4 nm in diameter. Structural and morphological analyses were performed. Gas measurements were carried out. The Pd-nano-clusters covering the sensitive layer significantly affect the gas sensitivities and the corresponding dynamic response. For example the sensors reaction to CO exposure is significantly different in two points in comparison to a sensor without nano-sized clusters: even at room temperature CO can be detected and the sensitivity is increased at all investigated operation temperatures of the sensor. Nevertheless the CO sensitivity maximum still is around 400 °C, which corresponds with the maximum of O^- adsorption on the surface. Palladium acts as a catalyst for dissociating O²- to O^-.

Sacrificial etching is one of the most important process steps in Micro-Electro-Mechanical Systems (MEMS) technology, since it enables the generation of free-standing structures. These structures are often the main part of micro-mechanical devices, intended to sense or induce a mechanical movement. The etching process transforms an initial multi-segmented geometry and depends on material properties and several process conditions. One of the crucial issues for etching is the etching selectivity on different materials. The major task for the simulation is to give an answer, how sacrificial layer surfaces regress in time under the influence of process parameters and to which magnitude surrounding material segments are affected by the etching process. For this purpose we have developed a full three-dimensional topography simulation tool, Etcher-Topo3D, which is capable to deal with realistic process conditions. The main concept is demonstrated in this work. During simulation the topography of the initial multi- segment geometry is changed which is handled by a level-set algorithm. After a simulation is finished, the level-set representation has usually to be converted back to a mesh representation to enable further analysis. For illustrating the main features of our simulation tool several examples of a MEMS structure with a sacrificial layer are presented.

A PZT thick-film is printed on an Al₂O₃-Substrate, generating a cantilever monomorph. A task of positioning with two degrees of freedom is successfully fulfilled. It is realized by two parallel arranged cantilevers that are mechanically combined with a bar with solid hinges. The solid hinges allow flexibility for different amounts of bending of the two cantilevers, while the bar permits a stiff support for a lens. As the bar underlies very small torsion there is no stress induced change in the index of refraction of the lens. Different combinations of hinges are simulated and practically tested. In the presented work, a lens is successfully positioned in front of a laser diode. The loss of the coupling efficiency due to the shrinking of the adhesive joint can be scaled down. The paper presents the theoretical work including the report on analytic and FEM simulation of both deflection and stress. The practical validation is also presented. A simple sensor system is used to find an optimized position of the lens in front of the diode. This position is automatically held over a long period of time. With the fabrication of the actuator using thick-film printing and laser cutting a low cost device is built.

The main objective of this paper is to develop a distributed architecture for integrating MEMS based on a hierarchical communications system governed by a master node. A micro-electromechanical system (MEMS) integrates a sensor with its signal conditioner and communications interface, thus reducing mass, volume and power consumption. In pursuing this objective, we have developed an Intellectual Propriety (IP) model with VHSIC Hardware Description Language (VHDL) for the bus interface that can be easily added to the micro-system. The connection between the MEMS incorporating this module and the sensor network is straightforward. The core thus developed contains an Interface File System (IFS) that supplies all the information related to the microsystem that we wish to connect to the net, allowing the specific characteristics to be isolated to the micro-instrument. This allows all the nodes to have the same interface. In order to support complexity management and composability, there are a real-time service interface and a not timecritical configuration interface. So the design includes a new node integration VHDL module. The design has been implemented in a Field Programmable Gate Array (FPGA) and was successfully tested. The FPGA implementation makes the designed nodes small-size, flexible, customizable, reconfigurable and reprogrammable with advantages of well-customized, cost-effective, integration, accessibility and expandability. The VHDL hardware solution is a key feature for size reduction. The system can be resized according to its needs taking advantages of the VHDL configurability.

The focus of this paper is on the optimization of a novel angular rate sensor element based on the Coriolis force working principle. The device is resonantly excited and consists of two coupled, mechanical oscillators representing the drive and the sense unit. To minimize energy loss during operation, the device is connected at one single point to the substrate. This kind of suspension is especially advantageous when choosing an antiphase torsional motion between the drive and sense unit. Furthermore, temperature effects on the device characteristics are reduced. The drive unit is typically excited in the frequency range of 10 to 15 kHz using electrostatic forces. To achieve optimized signal levels the geometry of the sensor is completely parameterized. An analytical model is set up via the so-called deformation algorithm applying the Ritz method. Next, the eigenfrequencies and mode shapes of the sensor were calculated. After including the effects of the Coriolis force, the corresponding change in capacity of the sense unit is determined. An advanced hill climbing algorithm is used varying two geometrical parameters simultaneously. This pair of parameters is changed in such a way that the difference in drive and sense frequencies is fixed to 200 Hz. Based on this procedure an optimized design could be found with an increase in signal levels of about 450% concerning an earlier version (e.g. from 3 to 17 aF°/s). In addition, FEM (Finite Element Method) simulations are performed to check the analytically calculated eigenfrequencies and mode shapes. Both approaches show comparable results.

In the present work, a rigorous two-dimensional physical simulator is developed to characterize the operation and to optimize the structure of a highly sensitive linear 2D MOSFET magnetic sensor. The magnetic field equation and the carrier transport equations are efficiently coupled and accurately solved to determine the effects of external applied magnetic field on the electrical characteristics of the MOSFET based sensor. The accuracy of the present simulator is tested for different device and circuit parameters to allow the use of it as an efficient CAD tool to fully characterize smart two-directions MOSFET magnetic sensor.

This paper used the theoretical calculation to simulate the response of Surface Acoustic Wave (SAW) delay-line on quartz substrate and then compared to the experimental results. The coupling coefficients affected by operating frequency as well as aperture length were built up by experimental data analyzing. From these two parameters, the device coupling coefficient was defined. This is our new contribution and has not been mentioned in other document. This contribution helped improve the simulation results and help the analysis process more comprehensive. ST-cut quartz SAW delay-lines with gold inter-digital transducer (IDT) operating at 39.5MHz and 78.9MHz corresponding to 80 micron and 40 micron of the wavelength were developed. The differences of aperture length in IDT designs were investigated to help understand the effects of this parameter on SAW sensor response. The errors between simulation and experimental results are small. The maximum error of operating frequency is 1%; of insertion loss is 4.25% and 3.13% for bandwidth. The larger of the insertion loss error is explained to be the result of mathematical approximation and the quality of quartz substrate. The simulation results agree with the experimental results shows that the simulation method can be used for quartz-based SAW delay-line as well as for other material based SAW delay-line applications; the sensors functioned correctly and can be used. The results help understand more about the parameters which effect the insertion loss, operating frequency and bandwidth. It should be very useful for IDT design in specific, SAW sensor and SAW filter design in general.

This paper presents a domotic application. Due to the impossibility of carrying out a domotic installation on a real house, we have built a scale model of the house, and adapted all the sensors, the actuators and the control system to this scale model. This simulation of a domotic installation has been developed for educational tasks. The final objective of this work is to allow the students of the Engineering Technical School of the University of La Laguna to learn the control of the domotic installation.