W.-J. Fischer

Fraunhofer Institute for Photonic Microsystems IPMS, Dresden, Saxony, Germany

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Publications (79)23.38 Total impact

  • S. Sauer, W.-J. Fischer
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    ABSTRACT: Passive RFID transponder applications that require integrated sensors can greatly benefit from unconventional sensing strategies especially in situations where there is a need to continuously monitor environmental properties without having access to an integrated source of electric energy or an omnipresent reader station within communication range. Since, in many cases, information about the violation of a threshold value is of interest, alternative sensing strategies exploiting irreversible phenomena not considered or even avoided before, have the potential to find successful use in low-cost (e.g., chip-based sensor RFIDs) or lowest cost (e.g., chipless sensor RFIDs-either with or without transistors) wireless sensor applications. In this paper, a stand-alone, simple, passive, wireless humidity threshold sensor concept, and its realization are presented. This exploits the deliquescence phenomenon of salts. Based on a double planar coil arrangement, for which an electric model is given and a transfer function has been deduced, an oscillating circuit is formed. Its resonance frequency changes irreversibly, if a threshold relative humidity is exceeded for a certain exposition time. The sensor principle is demonstrated by the example of sodium chloride. Various measurements demonstrate the feasibility of the presented sensor approach. Sensor solutions based on a threshold activated irreversible state change might be a promising approach in order to monitor environmental parameters without a permanent supply of electric energy.
    IEEE Sensors Journal 01/2014; 14(4):971-978. · 1.48 Impact Factor
  • Journal of The Electrochemical Society 11/2013; 161(1):D26-D30. · 2.59 Impact Factor
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    ABSTRACT: This paper describes new active composite structures based on thermoplastic matrices which contain material homogeneous embedded piezoceramic modules. Starting point is the development of novel thermoplastic compatible piezoceramic modules, so called TPMs. By the utilization of the same matrix material for the composite structure and for the TPM carrier films, these modules afford an opportunity to become directly embedded into the component during its manufacturing process. In this context, the manufacturing technology of the TPMs and of the active composite structure is presented. Furthermore, selected test samples are investigated concerning their modal behavior. Based on the determined characteristics a linear two-port model is used for the reproduction of the experimental results.
    ASME 2013 Conference on Smart Materials, Adaptive Structures and Intelligent Systems SMASIS2013, Snowbird, UT; USA; 09/2013
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    ABSTRACT: The determination of wine additives such as sulfur dioxide and ascorbic acid is motivated by limiting these substances because of their potential noxious effects. Cyclic voltammetry with inkjet printed electrodes on a PET foil was used to quantify free sulfur dioxide and ascorbic acid in a model wine solution. Two different kinds of electrodes were manufactured: Silver electrodes and silver electrodes modified with gold nanoparticles. Inkjet printed electrodes showed high sensitivity and selectivity towards ascorbic acid and sulfur dioxide and a linear relationship between concentration and peak current was observed. Modification of the inkjet printed silver electrode with gold nanoparticles increased the sensitivity. Additionally, more defined current peaks were obtained, that proved the excellent suitability of the silver electrodes modified with gold nanoparticles for precise determination of sulfur dioxide and ascorbic acid in wine.
    Sensors, 2013 IEEE; 01/2013
  • S. Sauer, A. Turke, A. Weder, W.-J. Fischer
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    ABSTRACT: Continuous monitoring of environmental parameters to determine threshold or dosage violations is of strong interest throughout the life cycle of goods. The task is challenging, when there is no continuous supply of electric energy available and lowest cost sensor solutions are required - two common application constraints in passive RFID applications which are also required to fulfill monitoring tasks. Presented is a humidity threshold violation sensor concept, in which the exceedance of a humidity threshold value leads to a permanent sensor resistance change. The principle is based upon the deliquescence of salts as a threshold detection mechanism, as well as chemical sintering of metal nanoparticles, used as irreversible state change mechanism. The introduced sensor arrangement is completely inkjet printed. Several experiments demonstrate the feasibility of the approach. Due to the strong resistance change, the sensor elements can serve as humidity triggered switches in electric circuits as demonstrated by the integration into a freely programmable RFID UHF transponder tag.
    Sensors, 2013 IEEE; 01/2013
  • Sensors & Transducers Journal. 01/2013; 18.
  • Proc. 11th Int. Conf. on Nanoimprint and Nanoprint Technology; 01/2012
  • R Kirchner, A Finn, A Chares, M Vogler, W -J Fischer
    Proc. 11th Int. Conf. on Nanoimprint and Nanoprint Technology; 01/2012
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    ABSTRACT: For wine industry, the quality of the produced wine is very important. Sulfur dioxide (SO2) is used as an antioxidant and preservative. But also ascorbic acid plays an important role in preventing oxidation. Therefore, there is a need for detecting these components in wines. Cyclic voltammetry was used to determine SO2 and ascorbic acid in a pH 3.3 model wine solution. In literature, modified electrodes showed advantages compared to bare electrodes. For this reason a gold electrode covered with poly(3,4-ethylenedioxythiophene) (PEDOT) was used. In the simultaneous presence, well defined separated current peaks for SO2 and ascorbic acid were detected, which proved the excellent suitability of the PEDOT covered gold electrode for precise determination. A linear relationship between concentration and peak current was observed.
    Sensors, 2012 IEEE; 01/2012
  • S. Sauer, W. Fischer
    [Show abstract] [Hide abstract]
    ABSTRACT: Passive RFID transponder applications, requiring integrated sensors, can greatly benefit from unconventional sensing strategies. Especially in situations where there is the need to continuously monitor environmental properties, but without having access to an energy source or an omnipresent reader station in communication range. Since in many cases the violation of a threshold value is of interest, alternative sensing strategies, exploiting irreversible phenomena not considered or even avoided before, have the potential of finding a successful use in low cost (e.g. chip-based sensor RFIDs) or lowest cost (e.g. chipless sensor RFIDs) wireless sensor applications. In this work, a stand-alone, simple, passive, wireless humidity threshold sensor is presented, which exploits the deliquescence behavior of salts. Based on a double planar coil arrangement, an oscillating circuit is formed. Its resonance frequency irreversibly changes, if a threshold relative humidity is exceeded for a certain exposition time.
    Sensors, 2012 IEEE; 01/2012
  • Journal of Photopolymer Science and Technology 01/2012; 25:197. · 0.98 Impact Factor
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    ABSTRACT: A method and a simplified analytical expression are presented for the calculation of the effective reluctance of a magnetic substrate underneath a planar coil as parameter in a simplified electromechanical network model. The investigated magnetic substrates have a toroid geometry with rectangular cross section, different thicknesses and permeabilities. The method is based on a combined simulation of the magnetic quantities where network parameters are determined by a Finite Element simulation. A network transformation allows the computation of partial inductances which are related to the reluctances. Depending on thickness and permeability the effective substrate reluctance differs from a geometrically based reluctance calculation, where an axisymmetric field distribution without axial component is assumed. From the almost linear relation between the reluctances a correction factor can be given. This factor allows the simplified calculation of the effective reluctance of a magnetic substrate underneath a planar coil.
    Sensors, 2012 IEEE; 01/2012
  • R Kirchner, L Nueske, A Finn, B Lu, W -J Fischer
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    ABSTRACT: Defects to due resist pre-exposure as well as the relevance of the initial film thickness during stamp-and-repeat UV-assisted nanoimprint lithography are reported. The demolding force was found to be an indirect measure for the development of the photoinitiator concentration and for the curing behavior of the resist. Multiple imprints into pre-exposed resist are possible due to oxygen cure inhibition. The first curing defects due to significantly reduced photoinitiator concentrations in UVCur21SF resist occurred at accumulated doses of about three times the imprint dose. Molds having only a small fraction of patterned area require very thin initial films with an thickness being optimized for the low mold cavity volume. Helium is essential for the complete mold filling from such thin spin coated films.
    Microelectronic Engineering 01/2012; 97:117-121. · 1.22 Impact Factor
  • Sebastian Sauer, W.-J. Fischer
    Procedia Engineering 01/2012; 47:750 - 753.
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    ABSTRACT: A fully ink jet printed humidity sensor on a thin PET foil is presented in this paper. Conductive silver electrodes were ink jet printed in the first step. Afterwards film forming polymer particles were printed on top as the humidity sensitive layer. Capacitance measurements were performed to investigate the sensor behavior at different humidity levels. By optimization of the electrode printing parameters the required sensor area was significantly reduced. Systematic investigations for the improvement of the humidity dependent layer led to a suitable polymer film, which combines good processability by inkjet printing with adequate humidity sensitivity and small hysteresis. The proposed sensor shows a high potential for low cost applications, which requires thin and flexible humidity sensors. For the correction of the nonlinear sensor transfer function a correction function with three calibration points is proposed.
    Sensors, 2012 IEEE; 01/2012
  • Source
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    ABSTRACT: The embedding of sensor networks into textile-reinforced thermoplastics enables the design of function-integrative lightweight components suitable for high volume production. In order to investigate the mechanical behaviour of such functionalised composites, two types of bus systems are selected as exemplary components of sensor networks. These elements are embedded into glass fibre–reinforced polypropylene (GF/PP) during the layup process of unconsolidated weft-knitted GF/PP-preforms. Two fibre orientations are considered and orthotropic composite plates are manufactured by hot pressing technology. Micrograph investigations and computer tomography analyses show different interface qualities between the thermoplastic composite and the two types of bus systems. Mechanical tests under tensile and flexural loading indicate a significant influence of the embedded bus system elements on the structural stiffness and strength.
    Materials and Design 12/2011; 32(10):4931-–4935. · 2.91 Impact Factor
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    ABSTRACT: This paper presents the development and use of novel concise mode diagrams as a fast and useful tool for designing planar optical waveguides. By usage of these mode diagrams, the waveguide geometry and materials can be conveniently chosen. The mode diagrams calculated with the so called Matrix-EIM are particularly useful for the design of straight planar waveguides manufactured by nanoimprinting to choose suitable combinations of polymers, geometries and substrates. The results correspond well to a commercial FEM solver and can be obtained faster. Some examples for UV-nanoimprinted polymers on oxidized standard silicon wafers are shown.
    IEEE Sensors 2011; 10/2011
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    ABSTRACT: Three dimensional (3D) spacer fabrics are constructed from two dimensional (2D) woven fabrics connected by 2D woven crosslink fabrics using thermoplastic high performance hybrid yarns. Spacer fabrics present great potential in the efficient production of fiber reinforced plastic composites with adjustable mechanical properties targeted for specific applications in Lightweight engineering. The structure of the weave and the stresses placed on the fibers during the weaving process impact the mechanical properties of the finished composite. This study shows that the mechanical properties can be significantly controlled and adjusted by pattern development of the individual 2D composite structures from the 3D spacer fabric preforms constructed of orthogonal multilayer weaves (non-crimped fiber arrangement and a gentle weaving process). Electrically conductive fibers are woven directly into various layers of the 2D woven fabrics and are therefore successfully integrated during production. This forms the basis for function integration in the composite. The weaving technology ensures a reliable contact of the conductive fibers allowing sensor networks to be integrated into the fabric for online monitoring of the fiber reinforced plastic composite component.
    Journal of Thermoplastic Composite Materials 09/2011; · 0.75 Impact Factor
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    ABSTRACT: The combination of Network Methods and Finite Element Methods on user level is a time-efficient method for the simulation of dynamic behavior of electromechanical systems. Combined simulation can be structured into five areas of application: determination of network structures with FE-simulations, determination of network parameters with FEsimulations, inclusion of network elements in FE-models, inclusion of equivalent network structures in FE-models and simulation of models incorporating different model levels. The capabilities of the combined simulation are demonstrated by sample applications. Combined Simulation is suited for a better system insight and fast simulation-based optimization.
    Proc SPIE 03/2011;
  • E. Starke, M. Krause, G. Pfeifer, W.-J. Fischer
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    ABSTRACT: To achieve an efficient simulation of the dynamic behavior of electromechanical devices it is often necessary to use more than one simulation method or program. The main reason for this is that electromechanical systems contain different physical domains and transduction principles. In many cases a smart solution is the combination of network methods with finite element methods on user level which is referred to as combined simulation. This paper deals with one area of application of the combined simulation, which is the use of network methods to improve finite element models. After the description of the method the procedure is illustrated by the example of the model of a hearing aid.
    Proc SPIE 03/2011;

Publication Stats

126 Citations
23.38 Total Impact Points

Institutions

  • 2007–2012
    • Fraunhofer Institute for Photonic Microsystems IPMS
      Dresden, Saxony, Germany
  • 1999–2011
    • Technische Universität Dresden
      • • Institute of Semiconductors and Microsystems
      • • Fakultät Mathematik und Naturwissenschaften
      Dresden, Saxony, Germany
  • 2003
    • RMIT University
      • School of Electrical and Computer Engineering
      Melbourne, Victoria, Australia
  • 1997
    • Fraunhofer Institute for Microelectronic Circuits and Systems IMS
      Duisburg-Hamborn, North Rhine-Westphalia, Germany