The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
In this paper, we experimentally verify the difference between the zero reflection condition and the power maximization approach for the optimal electric loads. First, we predict those optimal loads with the KLM model for a 1–3 composite transducer that we use as a receiver, and we then perform experiments in deionized water with different ohmic loads attached to it. The measurements confirm that...
In this paper, we compare the zero reflection and the power maximization conditions to calculate the optimal electric load for maximum US energy absorption by receivers with the KLM model. In experiments with a 1–3 composite transducer, the predictions agree with the measurements at the resonance frequency. Results at the anti-resonance deviate slightly from predictions due to a parasitic load and...
Spring-mass matching layers consisting of a thin polymer layer (“massless spring”) covered by a metal layer (“incompressible mass”) can be designed to achieve any desired acoustic impedance and act as an equivalent λ/4 matching layer. In this paper, we present a fabrication process of these matching-layers based on spin-coated PDMS as spring layer and stainless steel commercial foils as mass layer.
We report on a solid state adaptive lens based on an elastomer lens body and an active glass-piezo composite membrane. In contrast to existing lenses with integrated actuation, this allows for the control of the aspherical behavior and has a large aperture of 6.25 mm at 7.9 mm outer diameter (9 mm including packaging). Using a polymer instead of a fluid as a refractive medium gives a good robustness...
We hereby introduce the biomaterial shellac as a new player in the field of sustainable microfluidics. We demonstrate a fully “green” technological process for wafer-level fabrication of microstructures by means of shellac hot embossing. The process is labeled as “green” because it can be carried out completely outside the cleanroom, it is fast, cheap, energy saving, and uses natural and exclusively...
We present a novel approach for 3D microstructuring of amorphous soft magnetic alloys. Our unique process is MEMS-compatible and leaves the magnetic properties of the alloys intact. The applicability of the process has been demonstrated in the fabrication of closed-loop core microtransformers. The magnetic core is fabricated using Metglas 2714A, cobalt-based magnetic alloy. The microtransformers show...
We demonstrate a scannable optofluidic slit based on electrowetting on dielectrics. The device is operated in full-field or slit mode. Switching times for a 100 μm wide scanning slit are below 120 ms.
We report on a novel micro-fabricated probe for nuclear magnetic resonance (NMR), based on two 1.5 mm diameter copper micro-coils, which are arranged in a Helmholtz configuration. The probe features a U-shaped slit opening to accommodate a sample and to precisely align it with respect to the sensitive, homogenous magnetic volume of the Helmholtz-pair. For liquids and suspensions, custom fabricated,...
Vortex beams with an optical angular momentum (OAM) are of increasing interest for optical tweezers [1], materials processing [2] or quantum information [3]. For specific applications, ultrashort wavepackets with OAM are required. Recently, 2.3-cycle vortex pulses were generated with an optical parametric amplification system [4]. From a more compact setup with a self-compensated diffractive spiral...
We present the fabrication of 3D-microtransformers combining a new type of multilayered magnetic core and coil winding with an automatic wirebonder. For the magnetic cores we stapled up to 30 layers of 20 μm thick amorphous metal layers with an industrial laminator. Intermediate layers of 10 μm thick double-sided sticky tape provided adhesion and electrical insulation. Electrical discharge machining...
In this work we present a new manufacturing method for MEMS based multi-level microfluidic devices. The combination of spin-coating SU-8 (MicroChem) and lamination of PerMX dry-photoresist (DuPont) enables the fabrication of a complex 3-level microfluidic channel network with channel aspect ratios ranging from 0.3 up to 3. On 13 mm2 fluidic chip area we realized a complex 3D fluidic network by interconnecting...
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 µWavg at 1 ms−2 was generated. Our approach evidences that...
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...
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...
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...
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....
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...
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...
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...
We present high-performance MR imaging and spectroscopy results obtained with wire bonded solenoidal microcoils manufactured in a MEMS-integrated technology. We report MR testing of 400 μm inner diameter solenoidal microcoils for imaging of Eremosphaera Viridis algal cells with 10 μm isotropic resolution. NMR spectroscopy has been performed on a water sample obtaining a linewidth of 0.04 ppm. The...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.