Search

We present a controlled mode of ‘topological’ displacement of homogeneous piezo films that arises solely from an inhomogeneous in-plane strain due to an inhomogeneous polarization. For the rotationally symmetric case, we develop a theoretical model that analytically relates the shape of the displacement to the polarization for the cases of in-plane and out-of-plane polarization. This is verified experimentally for several examples, and we further demonstrate controlled asymmetric deformations.

In microsystems engineering the understanding of tribological behaviour on the microscale is one of the key factors in the design of devices with moving parts such as micromotors. This study has investigated the friction coefficients of LIGA processed nickel rotor samples on an alumina substrate and how the measured friction was affected by wearing the nickel rotors. The nickel rotors are typical of those that would be used in electrostatic micromotors. The rotors were loaded only by their own mass, resulting in normal forces of as low as 10−7 N. High coefficients of friction were measured for the smallest rotor samples. A relationship was found linking the mass of the rotor samples and the measured coefficient of friction, which showed, that for very small rotors and light loads, the friction coefficients can be very high. This is obviously a major concern for the miniaturisation of devices, if they are to work efficiently (or at all). The mass dependence relationship was investigated for increasing wear of the rotor samples and found to be less apparent with wear. It is suggested that this is a direct result of the increase in true contact area as wear progresses, resulting in a decreased sensitivity to the load.

Adaptive autocorrelation with an angular tunable micro-electro-mechanical system is reported. A piezo-actuated Fresnel bi-mirror structure was applied to measure the second order autocorrelation of near-infrared few-cycle laser pulses in a non-collinear setup at tunable superposition angles. Because of enabling measurements with variable scaling and minimizing the influence of distortions by adaptive self-reconstruction, the approach extends the capability of autocorrelators. Flexible scaling and robustness against localized amplitude obscurations are demonstrated. The adaptive reconstruction of temporal frequency information by the Fourier analysis of autocorrelation data is shown. Experimental results and numerical simulations of the beam propagation and interference are compared for variable angles.

We present a tunable reflective blazed-grating for the use with high energy femtosecond laser pulses. The technology is based on the surface deformation of a viscoelastic polymer induced by the volume shrinkage of the polymer during crosslinking. The blaze-angle of the grating is tunable by thermal actuation. Thermal actuation and light propagation have been characterized.

In this contribution we present a fast and robust adaptive Fresnel mirror for advanced nanomachining applications with femtosecond lasers. The Fresnel mirror consists of two mirror segments that are actuated with a piezoelectric bimorph. All components are fabricated by low-cost rapid prototyping processes without the need for a clean-room. Light propagation and pulse transfer have been characterized as well as the static and dynamic actuation properties.

International audience; This article describes the development and testing of the first automatically microfabricated probes to be used in conjunction with the magic angle coil spinning (MACS) NMR technique. NMR spectroscopy is a versatile technique for a large range of applications, but its intrinsically low sensitivity poses significant difficulties in analyzing mass- and volume-limited samples. The combination of microfabrication technology and MACS addresses several well-known NMR issues in a concerted manner for the first time: (i) reproducible wafer-scale fabrication of the first-in-kind on-chip LC microresonator for inductive coupling of the NMR signal and reliable exploitation of MACS capabilities; (ii) improving the sensitivity and the spectral resolution by simultaneous spinning the detection microcoil together with the sample at the “magic angle” of 54.74° with respect to the direction of the magnetic field (magic angle spinning – MAS), accompanied by the wireless signal transmission between the microcoil and the primary circuit of the NMR spectrometer; (iii) given the high spinning rates (tens of kHz) involved in the MAS methodology, the microfabricated inserts exhibit a clear kinematic advantage over their previously demonstrated counterparts due to the inherent capability to produce small radius cylindrical geometries, thus tremendously reducing the mechanical stress and tearing forces on the sample. In order to demonstrate the versatility of the microfabrication technology, we have designed MACS probes for various Larmor frequencies (194, 500 and 700 MHz) testing several samples such as water, Drosophila pupae, adamantane solid and LiCl at different magic angle spinning speeds.

Flexible silicone membranes are key components for tunable optical lenses. The elastic operation of the membranes impedes the use of classical layer systems for an antireflective (AR) effect. To overcome this limitation, we equipped optical elastomer membranes with “moth-eye” structures directly in the flexible silicone substrate. The manufacturing of the AR structures in the flexible membrane includes a mastering process based on block copolymer micelle nanolithography followed by a replication method. We investigate the performance of the resulting AR structures under strain of up to 20% membrane expansion. A significant transmittance enhancement of up to 2.5% is achieved over the entire visible spectrum, which means that more than half of the surface reflection losses are compensated by the AR structures.

Electrostatic stepping micromotors have been designed with regard to low rotor friction on the axle. The design rules are determined using two-dimensional FEM calculations and taking into consideration the particular rotor position during motion. The motors are fabricated by a fully integrated LIGA process. The minimum driving voltages needed are measured to be about 60 V. Determination of the coefficients of friction in operation completes the rules for future designs.

A cantilever microactuator made of a ceramic fibre was used to load LIGA processed microstructures by pushing them over different substrates. Static and kinetic friction coefficients in air were determined for the interfaces between the LIGA-processed microstructures and the different substrates. Microrotors disassembled from electrostatic micromotors made of Cu and Ni have been used for the experiments. The substrate materials were amorphous Al2O3 and sputtered Ag on Cr. The experiments were carried out in a clean environment under class 100 conditions. Different cleaning methods and surface treatments have been applied and the influence on the coefficient of friction studied. It was found that the cleanliness of the surface and adsorbed gas layers have a substantial effect on the static friction results. This dependence was higher for Cu than for Ni. The kinetic and static friction appeared to be lowest for sliding on the Ag substrate and sliding of Ni on sputtered Ag exhibited the lowest coefficients of friction.

We present a lab on a chip (LOC) compatible modular platform for magnetic resonance (MR)-based investigation of sub-millimetre samples. The platform combines the advantages offered respectively by microcoils (high resolution at the microscale) and macroscopic surface coils (large field of view) as MR-detectors and consists of a phased array of microcoils (PAMs) providing a flat MR-sensitive area of 18.3 mm(2) with a B(0)-field uniformity better than 0.25 ppm in the sensor centre area. We demonstrate both high-resolution magnetic resonance imaging (MRI) and NMR spectroscopy using this platform. To demonstrate the application for biological samples, we report MR imaging of fish oocytes with an in-plane resolution of 30 × 30 μm(2) and a contrast to noise ratio of 10 for a scan time of only 13 min 39 s. We have also demonstrated high-resolution spectroscopy of a water phantom achieving 11 ppb (4.5 Hz at 400 MHz) linewidth and an SNR of 28 for only 12 s scan time. State of the art automatic wire bonding technology in conjunction with MEMS techniques has been employed to manufacture the platform with potential applications in MR-investigation of planar samples.

In this paper we present a new fabrication method that combines for the first time popular SU-8 technology and PerMX dry-photoresist lamination for the manufacturing of high aspect ratio three-dimensional multi-level microfluidic networks. The potential of this approach, which further benefits from wafer-level manufacturing and accurate alignment of fluidic levels, is demonstrated by a highly integrated three-level microfluidic chip. The hereby achieved network complexity, including 24 fluidic vias and 16 crossing points of three individual microchannels on less than 13 mm(2) chip area, is unique for SU-8 based fluidic networks. We further report on excellent process compatibility between SU-8 and PerMX dry-photoresist which results in high interlayer adhesion strength. The tight pressure sealing of a fluidic channel (0.5 MPa for 1 h) is demonstrated for 150 μm narrow SU-8/PerMX bonding interfaces.

We introduce a closed-loop pressure control of a single chamber adaptive fluidic membrane lens with an integrated piezoelectric bending actuator. For this purpose a pressure sensor is integrated into the lens and allows for a measurement of the chamber pressure as a function of the refractive power. The linear relation between pressure and refractive power allows to eliminate the typical hysteresis effects of piezo actuators.

The particle swarm optimization (PSO) method is applied to a new parametric lens model based on Zernike polynomials as basis functions. A fluid membrane lens is optimized to yield a particular focal length. Measurements on a manufactured prototype verify the computed results.

In this contribution we present a fast and robust optical line shaping mirror for advanced nanomachining applications with femtosecond lasers. The line shaper consists of two mirror segments and is actuated with a piezoelectric bimorph, which allows for an easy and low-cost fabrication process. Light propagation and pulse transfer have been characterized.

In this Letter we report on the fabrication and testing of an extremely thin variable aperture stop based on the design of a single chamber adaptive membrane lens with integrated actuation. The aperture consists of a ring-shaped piezoelectric bending actuator with an elastic silicone membrane in the center. The formed cavity is filled with a nontransparent fluid and sealed with a glass platelet. In a voltage range up to 80 V, an opening of the aperture of 4.55 mm in diameter is obtained. The transmission in comparison to a standard mechanical aperture stop is maximum 6% lower.

We present for the first time a full characterization of a microbearing based on stabilized magnetic levitation. The device consists of two coaxial wirebonded solenoidal microcoils (2000 µm and 3600 µm diameter) for levitation and stabilization purposes respectively. We demonstrate controlled vertical positioning of an Al plate (25 µm thick, 3200 µm diameter) ranging up to 150 µm at an excitation signal with frequency f = 2 MHz and 105 mA effective current in the levitation microcoil. The positioning error is 2.6 µm.

We present for the first time wirebonded microcoils arranged in a planar phased-array configuration for large field of view (FOV) microscale magnetic resonance imaging (MRI) of 2D samples. The phased array consists of seven microcoils providing a sensitive area of 18.3 mm2. We demonstrate successful high-resolution imaging of a water phantom with 16 × 16 µm2 in-plane resolution and an signal-to-noise ratio (SNR) of 27 in 12 min 48 s acquisition time.

We introduce a flat micro energy harvester with a volume of 0.9 cm3 and a height of 3 mm. The combination of multiple magnetic circuits enhancing each others flux and one serpentine coil with a single winding and an effective copper filling factor of 100 % enables to maximize the output power. With a first prototype an average power of 12 µW avg at 1 ms−2 was generated. Our approach evidences that high power can be realized even with flat harvesters, although they typically suffer from high mechanically damping.

We developed the first micro energy harvester with optimized wire bonded microcoils. The coils were fabricated with a fully automated process on PCB. The 3D coils enable to effectively use the magnetic field and generate an output power of 0.62 µW at 1 ms−2 within a total harvester volume of 0.46 cm3. With the coil wire thickness of only 25 µm this corresponds to the high load voltage of 10.4 mV. The results evidence that this approach can help developing high performance energy harvesters with an increased output voltage.

In this work, we present the first mechanically tunable axicon mirror. The intended applications for such a device are nanomachining with high energy femtosecond lasers, microscopy and optical tweezers. The device consists of a piezodisc with structured electrodes, a reflective layer and a soft PDMS supporting ring that allows a rotational movement of the device around its outer perimeter. The performance of the device is optimized by an automated FEM-Simulation. A rapid prototyping fabrication process is presented as well as the mechanical and optical characterization of the system.

We report for the first time single-chip MEMS-integration of a resonant LC-circuit for wireless magic angle coil spinning (MACS) NMR. The chip consists of a wirebonded 3D microcoil, an interdigitated capacitor and a sample container. The LC-circuit resonates at 700MHz for 1H spectroscopy in 16.4T magnetic field. The microcoil is inductively coupled with the probe-coil of the spectrometer. We prove the high sensitivity of the setup by detecting the NMR signal from 0.3nl H 2 O in a mixture with deuterium oxide (0.1% H 2 O: 99.9% D 2 O) with an SNR=8.5 in one scan.

This paper reports a terahertz metamaterial consisting of 3-D microcoils fabricated with an automatic wire bonder in a fully MEMS-compatible manner. The response of the system to an incident electromagnetic wave was characterized by terahertz time-domain spectroscopy (TDS) and by numerical simulations. Depending on the light polarization relative to the structure, fundamental and higher order electric or magnetic resonances were excited in the coils.

For novel spatio-temporal pulse characterization techniques, adaptive materials processing [1], advanced microscopy, tweezers and other emerging applications, adaptive axicons capable to shape highly robust nondiffracting beams of variable parameters are of increasing interest. Conical phase profiles can be approximated by pixellated liquid crystal based spatial light modulators [2] which reach a high spatial resolution even at ultrashort pulses but suffer from limitations with respect to obtainable phase steps, switching speed, diffraction losses and damage resistance. One alternative approach is to combine the specific advantages of highly reflective analogue micro-electromechanical systems (MEMS) with the optical functionality of continuous conical axicon profiles [3]. This promises to work at minimum dispersion and minimum diffraction and, simultaneously, with extended undistorted propagation zones. Here we report on first experimental results obtained with a new type of tunable mechanical axicon mirror. Its design is based on a piezo-disk with 5 concentric circular electrodes (Ag) and a broadband reflecting aluminium layer on top (Figure 2). The local bending radii of the disk correspond to the voltages at the individual electrodes (≤ 60 V). The envelope phase function was approximated by automated FEM simulations (about 50 iterations). Beam propagation of shaped ultrashort pulses was simulated with VirtualLab (Light Trans). Supporting structures and the substrate for the mirror were fabricated from Si wafers coated with polydimethylsiloxane (PDMS) and aluminium, respectively. The surface quality was characterized interferometrically (Figure 1). A maximum initial bending of < 3 µm over 15 mm diameter was found. Voltage dependent shape variations were detected (a) for the stationary case by phase shift interferometry and with a laser profilometer, (b) by analyzing the far field intensity patterns of a cw source at 532 nm (Figures 2 c–e), and dynamically with a stroboscopic setup. It was shown that the device can be operated up to a frequency of 3 kHz. Variable Bessel-like zones (here indicated by narrow rings in the far field) were created by addressing variable combinations of electrodes (Figures 2 c–e). Femtosecond pulse transfer was studied with a Ti:sapphire oscillator (Venteon, pulse duration < 6 fs, spectral bandwidth > 200 nm, repetition rate 80 MHz) and an LX-SPIDER (APE) for detecting spectral phase changes. Scattering and slightly asymmetric angular profiles indicate small deviations from a perfect geometry which still have to be overcome. To conclude, adaptive MEMS axicon mirrors based on piezo-disks with multiple individually addressable electrodes were studied in proof-of-principle experiments. The capability to flexibly shape Bessel-like beams at ultrashort pulse durations was demonstrated. Improvements of quality and design, a further development of characterization techniques and applications in ultrashort-pulse physics are a subject of continuing experiments.

The goal of this paper is to provide a simple and effective optimization approach maximizing the output power of electromagnetic energy harvesters. The optimization is based on an equation enabling direct computation of the electromagnetic coupling. The output power is derived using only physical and geometrical parameters. Therefore, optimization can be applied earlier in the design process and the computation time can be reduced down to 50%. One first prototype evidences the effectiveness of this approach.

Recently, stacked dielectric polymer actuators have gained a lot of attention as MEMS actuators. In this paper we present a new kind of in-plane stack actuator. In contrast to its multilayer counterparts, it consists of only one active layer with inter-digitated microstructured soft electrodes which allow for a linear, radial or even asymmetric pulling motion in the working plane. The single layer design makes it in principle compatible with standard MEMS processes like deep reactive ion etching as well as silicone casting for optical components. Nevertheless, the wafer level fabrication process does not require any photolithography or clean room processes. The actuator consists of a microstructured layer of carbon black or nanotube filled PDMS which is suspended over a KOH etched trench on a (111) silicon wafer. The conductive PDMS electrodes are structured by laser ablation and subsequently embedded in a dielectric. The use of a (111) silicon wafer enables a mask less definition of the trench as the (111) layer is almost not attacked by the KOH etchant. The trench is defined by laser induced damage of the silicon wafer, so only exposed areas are etched. This allows for a true rapid prototyping of actuators with a fabrication time of less than one day.

We report on a thin zoom lens system using a compact design and an effective fabrication process for flat adaptive fluidic single chamber membrane lenses made of PDMS. The lenses consist of a ring shaped piezo bending actuator with a transparent silicone membrane in the center. A zoom ratio of Z = 1.42 is obtained using two lenses with a membrane diameter of 4 mm. The overall system thickness is only 4.4 mm.

We present high-performance MR imaging and spectroscopy results obtained with wirebonded solenoidal microcoils manufactured in a MEMS-integrated technology. We report MR testing of 400µm inner diameter solenoidal microcoils for imaging of Eremosphaera Viridis algal cells with 10µm isotropic resolution. NMR spectroscopy has been performed on a water sample obtaining a linewidth of 0.04ppm. The newly introduced MEMS technology naturally lends itself to the fabrication of microcoil arrays, thus enabling parallel high-throughput MR investigation. As a proof of concept we report flip-chip integration of a microcoil-array with a CMOS amplifier array. “Teflon grease” has been used as phantom and three spectra have been acquired simultaneously yielding a linewidth of 0.5 kHz and a spin sensitivity in the frequency domain of 1015 spins/Hz½.

In this work we introduce an extremely thin single chamber adaptive fluidic membrane lens with an integrated piezoelectric bending actuator. The height of the system is 1.76 mm and the membrane diameter 10 mm. The lens consists of a ring shaped piezo bending actuator with an optical clear silicone membrane in the center. A refractive power range of 11.3 dpt is achieved at a piezo voltage between ±40 V. The system shows a maximum resolution of 189 lp/mm measured at 50 % contrast and a focal length of 200 mm.

We present an adaptive membrane lens that is compatible with a magnetic resonance (MR) imaging system, as a part of an objective for in-bore optical motion tracking and correction. Compatibility tests with the high magnetic fields of a 3 T scanner and the shielding of the adaptive lens are discussed. For tracking of a marker an adaptive wide-angle objective has been designed and characterised. The measured mean distortions of the objective are between −2.05 and −2.6 %. The tracking system was verified in a MR scanner model.

We present the performance of a piezo-actuated compliant micromirror made of single crystal silicon, which is assembled with a compliant displacement amplification mechanism made of copper. Both of those two parts are purely based on the elasticity and deformation of thin beams. The measurement results reveal that our optical device achieves the specified function as a linear optical scanner, and that the kinetic motion and out-of-plane bending are under control.

We present for the first time a fully MEMS-integrated technology to manufacture 3D geometrically perfect solenoidal microcoils for microscale MRI applications. We report 25 microm isotropic resolution MR images of a copper sulfate aqueous phantom. These images are acquired using microcoils with 5 windings of insulated 25 microm diameter Au wire and with quality factors as high as 46 at the operating frequency (400 MHz).

We present a new 12° design rule to enhance the reliability of single crystal silicon (SCS) compliant mechanism with large deformation. This rule defines a suitable structure orientation on an SCS wafer and avoids failure of stress induced crystal slip on curved compliant beams. Our rule considers the crystalline directional properties, such as Young's Modulus and fracture strength, of SCS. We fabricated a rotational mirror as demonstrator which was displaced by a piezoelectric actuator. Obeying to the 12° design rule we achieved a 100% larger rotational angle at the mirror section than in case of arbitrary orientation.

Using the LIGA process combined with a sacrificial layer technique, microstructures with great structural heights and lateral dimensions in the micrometer range have been fabricated. These structures are used as microactuators. By using electrostatic linear actuators large displacements are achieved. A large torque is realized by a micromotor with a toothed rotor, friction being diminished by a rolling movement. Bimaterial elements based on PMMA and metal are designed to achieve a movement parallel to the substrate, to fabricate, for example, a gripper. Electromagnetic activation has been used to measure the fatigue behavior of LIGA micromechanical elements.

High-aspect-ratio 3D geometrically perfect solenoidal micro-coils are fabricated for the first time in a fully MEMS-integrated technology. Vertical micro-coils with up to 15 windings and diameters down to 100µm have been wound using an automatic wirebonder around SU8 and PMMA cylindrical posts. Using this method we also fabricate Helmholtz micro-coils capable to generate magnetic fields of 1mT, according to simulations. We demonstrate the potential to use large arrays of solenoidal micro-coils for energy harvesting applications by placing them in a sinusoidal magnetic field. The induced voltage is 1.4mV at 300kHz for a 7 windings micro-coil, in agreement with theoretical calculations.

We report on the increase of the sensitivity of variable reluctance inductive displacement sensors by the use of a novel comb configuration. In previous publications we showed that a comb configuration can be used to extend the traveling rage of electromagnetic actuators [1, 2]. This principle is now used for sensor applications. Experiments show an increase of sensitivity of 250 % for a configuration of 8 comb fingers compared to previously reported designs featuring only one finger [3]. Alternatively, very small air-gap widths can be avoided, rendering the sensors more robust and reliable to handle without sacrificing performance.

This work describes the fabrication and characterization of an electromagnetic micro generator array for energy harvesting purposes. The array consists of a magnetic polydimethylsiloxane (PDMS) membrane with 3x3 magnets which is aligned over a PCB with 3x3 coils. Different coil cores are tested and compared. The parameter for comparison is the voltage induced in the coil array by the vibrating membrane. The maximum measured voltage is 1.2 mV when exciting the converter array with an acceleration of 60 m/s2.

We present a synthesized sub-ps dual-wavelength laser source for digital holographic interferometry with a wide reconstruction range. The developed laser source generates two spectrally separated parts within one pulse. The sub-ps pulse duration desensitizes the holographic setup to environmental impacts. A center wavelength distance of only 12 nm with a high contrast was demonstrated by spectral shaping of the 50 nm broad seed spectrum of a CPA Ti:sapphire laser system centered at 800 nm. Time-resolved two-wavelength contouring requires the simultaneous and separable recording of two holograms. In general, a single CCD-camera is applied, and the spectral separation is realized by different reference wave tilts, which requires ambitious interferometric setups. Contrary to this, we introduce two CCD-cameras for digital holographic recording, thus essentially simplifying the interferometric setup by the need of only one propagation direction of the reference wave. To separate the holograms for the simultaneous recording process, a Mach-Zehnder interferometer was extended by a polarization encoding sequence. To study our approach of time-resolved digital holographic two-wavelength contouring, an adaptive fluidic PDMS-lens with integrated piezoelectric actuator served as test object. The PDMS-lens consists of an oil-filled lens chamber and a pump actuator. If a voltage is applied to the piezoelectric bending actuator the fluid is pumped into the lens chamber which causes a curvature change of the 60-μm thick lens membrane and thus a shift of the focal length. The dynamic behavior of the PDMS-lens, driven at a frequency of 1 Hz, was investigated at a frame rate of 410 frames per second. The measured temporal change of the lens focal length between 98 and 44 mm followed the modulation of the piezoelectric voltage with a 30 V peak-to-peak amplitude. Due to the performed time-resolved two wavelength contouring, we are able to extract the optical path length differences between center and perimeter of the lens. From the calculated phase difference maps we estimated large optical path differences of larger than 10 μm, corresponding to more than 15 times of the source wavelength.

We compare the performance and optical quality of two types of adaptive fluidic silicone-membrane lenses. The membranes feature either a homogeneous thickness, or it is shaped resulting in an inhomogeneous cross-section. The lens systems incorporate a piezo actuator which is operated in a regime of ±40 V. The shaped membrane lenses show lower wave front errors than the planar ones, down to 24 nm. However, the system with a planar membrane achieves a larger refractive power ranging from +19 to −14 dpt. It also shows a shorter full scale response time (t planar = 23.9 ms) compared to the shaped membrane (t shaped = 35.4 ms).

We present a new design procedure for a functional MEMS design and, simultaneously, for safe manufacturing. In order to verify our approach we chose a 2.5 D compliant rotational mirror as an example, which is fabricated in single crystal silicon. The design of this compliant mechanism is based on structural topology optimization [1] with subsequent modification by parameter optimization with a pseudo-rigid-body mode analysis [2]. The fabricated compliant mechanism has a linear input at the load point, which is pushed by a piezoelectric actuator, and a rotational output at the mirror section. This single crystal silicon mechanism achieves a rotational angle of 5° with a stationary rotational center at low frequency up to 50 Hz.

Introduction I. Technologies Innovative exposure techniques for 3-D microfabrication Large Surface Area Techniques PTFE photo-fabrication by SR (TIEGA process) Photomask Technologies Photomask Comparisons Galvanics and Molding Simulating New LIGA Processes Commercial Simulation Program Simulation Tools for Design Design for Assembly and Safe Manufacturing II. Applications Market Analysis and Commercialization of LIGA Optical MEMS and Polymer Optics Micromechanics RF Applications Evolution of the Spectrometer Microfluidics in Biotechnology MEMS (actuators) Microfluidics for Biochip Applications Ultrasonic Transducers Swiss Luxury Watches Using MEMS Components III. Outlook Extreme Nanostructuring Novel Resist Systems Hard Gold Interferential X-ray Lithography Table-top Synchrotrons for Future Light Sources and their Application in Microfabrication

We present the first adaptive microfluidic PDMS-lens system with an integrated piezoelectric pumping actuator. The system is fabricated in a highly streamlined fabrication process through casting via a hot embossing machine and subsequent oxygen bonding of the layers. With an optimized piezo actuator the achieved focal length ranges from 30 to 500 mm at a voltage from -9 to 44 V. We show that the lens resolution is crucially dependent on the thickness of the lens membrane. For an optimum thickness of 230 um at 5 mm diameter the lenses achieve a resolution of 120 linepairs/mm at a contrast of 50 %.

We present for the first time the development of 3-D solenoidal micro coils using an automatic wire bonder. By developing a stable and repeatable bond process with insulated wire, micro coils with sub-millimeter diameter have been manufactured. The winding process for a single coil takes about 200 ms, whereas the manufacture of a 100-coil-array takes less than a minute. Micro coils with 4 windings and a diameter of 690 mum exhibit an inductance of 12.7 nH and a resistance of 580 muOmega at 300 MHz. These values correspond to a quality factor of 41 and compare favorably lo state-of-the-art micro coil manufacturing technologies.

We present the first electromagnetic comb drive actuator which allows for large, linear actuator motion at large air gap widths of 25 mum and a structural height of 400 mum. Previously reported designs require very narrow air gaps of 3 mum at structural heights of up to 1 mm [1] which makes them sensitive to operate, and challenging to fabricate. The new design reduces the reluctance by a parallel connection of several pole shoes as is well known for electrostatic actuators, which reduces the current consumption and linearizes the current - displacement characteristic. Magnetic and mechanical material properties are measured for an accurate simulation of the system behavior. Experimental results verify the theoretical predictions.

A combination of an aspherical hybrid diffractive-refractive lens with a flexible fluidic membrane lens allows the implementation of a light sensitive and wide-aperture optical system with variable focus. This approach is comparable to the vertebrate eye in air, in which the cornea offers a strong optical power and the flexible crystalline lens is used for accommodation. Also following the natural model of the human eye, the decay of image quality with increasing field position is compensated, in the optical system presented here, by successively addressing different tilting angles which mimics saccadic eye-movements. The optical design and the instrumental implementation are presented and discussed, and the working principle is demonstrated.

The LIGA process[1] was first developed at the Forschungszentrum Karlsruhe GmbH. It is currently used worldwide by numerous other research institutes and by industry. LIGA allows for the manufacturing of microcomponents with almost arbitrary lateral geometry and resolution in the micron range, but with structure heights into the millimeter range. The typical materials used are polymers, metals, and ceramics, thus covering a wide range of “nonsilicon” candidates. The main process steps have given the technique its name, LIGA, a German acronym consisting of LI (Lithographie for lithography), G (Galvanik for electroplating), and A (Abformung for replication techniques, such as molding). In the classical understanding of LIGA, the lithography step is performed using the highly collimated and energetic X-rays of a synchrotron that can penetrate with little scattering into hundreds of microns of polymer resist and hence pattern it with extremely sharp, smooth, and vertical sidewalls. In addition, due to the short wavelengths of the X-rays, the spatial resolution of the process is very high, thus allowing for extremely high aspect ratios, i.e., the ratio of width over thickness of a structure. The overall process development requires establishing an entire process chain, e.g., a mask-making procedure, since X-ray masks need to be patterned with relatively high-aspect-ratio absorbing structures in a LIGA-like process, or an adopted sacrificial layer technique.

The need for low cost micro optical devices is increasing thru all application fields like tele- and data-communication, industrial automation, displays, automobile, sensor applications etc. Polymer technologies can follow this demand due to the possibility of mass fabrication by replication techniques. Various technologies have been developed in the past to fulfill the demanding requests given by the use of micro structures in optical applications. Part of them are already used in industrial manufacturing. Also demanding products are introduced into the market. In the paper we will give an overview of the relevant techniques and demonstrate their possibilities by a few product examples.

A process of UV-induced fabrication of single mode waveguides in a polymer microoptical bench has been realized that offers the unique feature of an inexpensive microstructure replication process for mass fabrication. Instead of using common mask techniques for the realization of the stripe waveguides, a "Self-masking" technique of the polymer by embossing a microoptical bench and a following UV-flood-exposure is used. The mould insert, which is necessary for the replication process was made by the LIGA-technique. The fabrication of the micooptical bench and the waveguides in the same process step assures very good alignment accuracy and guarantees a low cost passive fiber-chip coupling and assembly. The photoinduced chemical reactions of different homo- and copolymers of methylmethacrylate under different environmental condition have been investigated. It was shown that depending on the environmental conditions during photoinduced waveguide generation, the physical and chemical properties of the waveguides can be adjusted in a wide range. The process allows the realization of devices for application in telecommunication and sensor technology.

A novel design for a compact and robust micro optical distance sensor is presented. It is suitable for mass fabrication by micro molding known form the LIGA technique [1] and automatic assembly. Due to a modular design approach a distributed fabrication of the device modules is currently implemented. This allows a separate fabrication of the modules at several manufacturers each one being an expert for the special technology needed to fabricate the module. During the design phase not only the optical specification of the sensor system but also all requirements given by the manufacturers, such as easy manufacturability with high throughput as well as defined interfaces need to be considered.

The expansion of high capacity optical transmission techniques into price-sensitive areas such as datacom and access networks requires a major reduction in the cost of optical components. Polymer waveguides are attractive because they are very simple to process and are promising for low-cost devices. Deep UV-induced modification of the dielectric properties of polymers is a useful technique for low cost realization of integrated optical circuits for telecommunication und sensor applications. The technique presented here has several advantages with respect to common methods because only a single polymer layer is used, which serves as the substrate and waveguide as well and no further etching or development step is required. The integration of the waveguide circuits in a polymer microoptical bench offers the possibility of combining the devices with semiconductor based optical circuits and also achieve easy fiber-chip coupling. In this work, preliminary results of Y-junctions, directional couplers, multimode interference (MMI) couplers will be given.