J. Courbat

Universität Luzern, Luzern, Lucerne, Switzerland

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Publications (50)13.15 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: We have experimentally studied the variation in electrical resistance of flexible platinum lines patterned on polyimide foil when they are subjected to circular bending constraints. The lines were patterned by means of standard photolithography and sputtering deposition. Two different photolithography masks were used for comparative evaluation: an un-expensive transparency mask and a standard chromium mask. Measurements of the temperature coefficient of resistance (TCR) and time stability of the resistance have been acquired for lines bent down to 1.25 mm radius of curvature on a customized bending setup, showing good reliability results. The robustness of the lines has been also assessed by registering their change in resistance while bending at different radii of curvature. The lines showed reliability issues for radii of curvature below 1.25 mm, presenting a resistance variation of 19% for transparency mask-fabricated lines and 9% for chromium mask-fabricated lines. The worse reliability performances of transparency mask lines, compared to the chromium mask ones, was found to be due to their imperfect edges, which promoted the formation and propagation of cracks during bending. The results of the experiments in this work permitted to compare the performances of flexible conductive lines with different geometry and fabricated with two different masks, establishing quantitative and qualitative bending limits for their appropriate operation in flexible electronics systems.
    Microelectronics Reliability 01/2014; · 1.14 Impact Factor
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    ABSTRACT: The residual stress and buckling patterns of free-standing 8 mol.% yttria-stabilized-zirconia (8YSZ) membranes prepared by pulsed laser deposition and microfabrication techniques on silicon substrates are investigated by wafer curvature, light microscopy, white light interferometry, and nanoindentation. The 300 nm thin 8YSZ membranes (390 μm × 390 μm) deposited at 25 °C are almost flat after free-etching, whereas deposition at 700 °C yields strongly buckled membranes with a compressive stress of –1,100 ± 150 MPa and an out-of-plane-displacement of 6.5 μm. These latter membranes are mechanically stable during thermal cycling up to 500 °C. Numerical simulations of the buckling shape using the Rayleigh–Ritz-method and a Young's modulus of 200 GPa are in good agreement with the experimental data. The simulated buckling patterns are used to extract the local stress distribution within the free-standing membrane which consists of tensile and compressive stress regions that are below the failure stresses. This is important regarding the application in, e.g., microsolid oxide fuel cell membranes which must be thermomechanically stable during microfabrication and device operation. Keywords: Buckling; Free-standing Membrane; Micro-solid Oxide Fuel Cell; Pulsed Laser Deposition; Stress; Thin Film; Yttria-stabilized-zirconia
    Fuel Cells 08/2012; 12(4):614-623. · 2.36 Impact Factor
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    ABSTRACT: Due to their high specific energy and high energy density, miniaturized low-temperature (350-550°C) solid oxide fuel cells, hereafter abbreviated ―micro-SOFC‖, are believed to constitute one of the technologies that could help satisfy the continuously increasing electric energy demand for mobile devices such as laptops and camcorders. Using thin film and MEMS technologies, cathode-electrolyte-anode layer assemblies as thin as 1 μm are deposited on silicon substrates that are micromachined to form arrays of free-standing membranes (surface area: 390x390 μm2 at ETH Zurich). Proof of concept was already established by several groups and high power densities of several hundreds of mW/cm2 have been reported at temperatures as low as 350 °C. In Switzerland, the OneBat® consortium consisting of eight research groups is working on the development of the micro-SOFC technology covering various aspects such as membrane fabrication and characterization, reformer catalysis, thermal management and system development. After a brief presentation of the consortium activities as well as the state-of-the-art of the micro-SOFC research worldwide, this contribution will lay emphasis on the core of the micro-SOFC technology, namely the electrochemical cells, and address key-aspects for their further development: - fabrication and thermomechanical stability of free-standing membranes - development of cost-effective thin film deposition techniques - development of thermally stable electrodes
    10th European Fuel Cell Forum, Lucerne, Switzerland; 06/2012
  • 221st ECS Meeting221st ECS Meeting; 01/2012
  • ECS Transactions. 01/2012; 45:475.
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    ABSTRACT: We report on inkjet printing of silver nanoparticles on paper for the design of resistive temperature and capacitive humidity sensors. Temperature and humidity have shown to have an influence on the electrical and mechanical properties of the Ag printed structures on paper. The passivation of the paper substrate and the Ag structures with parylene was investigated to reduce these effects and improve the stability of the structures. The lines were printed with an average thickness of 0.8 μm and a resistivity of 30 μΩ·cm. The Ag thermometer coated with parylene showed a good linearity with a TCR of 0.0011°C<sup>-1</sup>, while the capacitive humidity sensor exhibited an exponential response. This study foresees the possibility of using paper as substrate with inkjet printing of silver for the design of low-cost environmental sensors.
    Solid-State Sensors, Actuators and Microsystems Conference (TRANSDUCERS), 2011 16th International; 07/2011
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    ABSTRACT: We report on the reliability of micro-heating elements made on a polyimide plastic foil. Tests on the maximum power the devices could withstand before failure and their aging when operating continuously at a constant temperature between 200 and 400°C were performed. They demonstrated that the hotplates can operate at continuous elevated temperatures at very low-power for more than a year. The deformation of the hotplate during operation and the failure mechanisms were studied. Such investigation is of interest for the design of robust metal-oxide gas sensors on foil to be integrated into smart sensing labels.
    Solid-State Sensors, Actuators and Microsystems Conference (TRANSDUCERS), 2011 16th International; 07/2011
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    ABSTRACT: 18th International Conference on Solid State Ionics. July 3 - 8, 2011. Warsaw, Poland. Due to their high specific energy and energy density, micro-solid oxide fuel cells1 (μ-SOFCs) are seen as one of the technologies that could help satisfying the continuously increasing demand for electric energy in portable electronic devices. The μ-SOFC is a less than 1 μm thin free-standing membrane. The membrane consists of ceramic and metallic thin film layers integrated on a micro structurable substrate based on MEMS technologies. In this study, Foturan® glass ceramic and silicon μ-SOFCs substrates are compared in terms of etching behaviour, mechanical and thermo-mechanical properties.
  • Procedia Engineering 01/2011; 25:1329-1332.
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    ABSTRACT: The design of ultra-low power micro-hotplates on a polyimide (PI) substrate supported by thermal simulations and characterization is presented. By establishing a method for the thermal simulation of very small scale heating elements, the goal of this study was to decrease the power consumption of PI micro-hotplates to a few milliwatts to make them suitable for very low power applications. To this end, the mean heat transfer coefficients in air of the devices were extracted by finite element analysis combined with very precise thermographic measurements. A simulation model was implemented for these hotplates to investigate both the influence of their downscaling and the bulk micromachining of the polyimide substrate to lower their power consumptions. Simulations were in very good agreement with the experimental results. The main parameters influencing significantly the power consumption at such dimensions were identified and guidelines were defined allowing the design of very small (15 × 15 µm) and ultra-low power heating elements (6 mW at 300 °C). These very low power heating structures enable the realization of flexible sensors, such as gas, flow or wind sensors, for applications in autonomous wireless sensors networks or RFID applications and make them compatible with large-scale production on foil such as roll-to-roll or printing processes.
    Journal of Micromechanics and Microengineering 01/2011; · 1.79 Impact Factor
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    ABSTRACT: The design of low-cost and low-power optical transducers on plastic foil for colorimetric gas sensors is proposed. The transducer was fabricated from PET or PEN foil on which polymeric micro-mirrors and colorimetric film were patterned using additive techniques. It consisted of a planar optical waveguide that was covered with an inkjet printed ammonia sensitive film for its evaluation. A parametric study was performed on the waveguide configuration to reduce the light loss and improve the gas sensing characteristics. The use of polymeric substrate made the device more cost effective and compatible with large scale fabrication, such as roll-to-roll processes. Combined with a low-power interface circuitry operating in pulsed mode, the limit of detection was defined as a function of the power consumption. Sub-ppm concentrations of NH3 were measured at a consumption of 868μW. Such potentially low-cost and low-power sensors foresee applications in the field of wireless systems, for environmental and safety monitoring.
    Sensors and Actuators B-chemical - SENSOR ACTUATOR B-CHEM. 01/2011;
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    ABSTRACT: With the emergence of the printed electronics industry, the development of sensing technologies on non conventional substrates such as plastic foils is on-going. In this article, we review the work performed and the trends in the development of environmental sensors on plastic and flexible foils. Our main focus is on the integration of temperature, humidity, and gas sensors on plastic substrates targeting low-power operation for wireless applications. Some perspectives in this dynamic field are also provided showing the potential for the realization of several types of transducers on substrates of different natures and their combination with other components to realize smart systems.
    Materials Today 01/2011; 14(9):416-423. · 6.07 Impact Factor
  • Jérôme Courbat, Danick Briand, Nico de Rooij
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    ABSTRACT: An all polymeric colorimetric gas sensor with its associated electronics for ammonia (NH3) detection targeting low-cost and low-power applications is presented. The gas sensitive layer was inkjet printed on a plastic foil. The use of the foil directly as optical waveguide simplified the fabrication, made the device more cost effective and compatible with large scale fabrication techniques, such as roll to roll processes. Concentrations of 500 ppb of NH3 in nitrogen with 50% of RH were measured with a power consumption of about 868 muW in an optical pulsed mode of operation. Such sensors foresee applications in the field of wireless systems, for environmental and safety monitoring. The fabrication of the planar sensor was based on low temperature processing. The waveguide was made of PEN or PET foil and covered with an ammonia sensitive layer deposited by inkjet printing, which offered a proper and localized deposition of the film. The influence of the substrate temperature and its surface pretreatment were investigated to achieve the optimum deposition parameters for the printed fluid. To improve the light coupling from the light source (LED) to the detectors (photodiodes), polymeric micro-mirrors were patterned in an epoxy resin. With the printing of the colorimetric film and additive patterning of polymeric micro-mirrors on plastic foil, a major step was achieved towards the implementation of full plastic selective gas sensors. The combination with printed OLED and PPD would further lead to an integrated all polymeric optical transducer on plastic foil fully compatible with printed electronics processes.
    Proc SPIE 08/2010;
  • J Courbat, D Briand, N F de Rooij
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    ABSTRACT: A generic method for the packaging of transducers at the foil level is proposed and was demonstrated on chemical gas sensors made on a plastic foil. The processing was based on the lamination of pre-patterned polymeric structures on the fabricated devices and covered by a gas permeable membrane. This polymeric packaging can be either applied on plastic foils or on conventional substrates such as silicon or glass. It can be used when standard packaging techniques might not be applied or when they can represent a significant cost. Using the lamination of a foil, the dry process presented here is compatible with large-scale fabrication techniques, such as roll-to-roll processing, and aims at reducing the global fabrication cost of sensing devices made on a plastic foil. It can further lead to the fabrication of all polymeric devices. This generic processing can be used for a wide range of applications in the field of microsystems, especially for which the foil level is required and where standard techniques at the wafer level are not applicable. The foil level packaging (FLP) was implemented here for the encapsulation of gas sensors on a plastic foil and validated through gas measurements.
    Journal of Micromechanics and Microengineering 04/2010; 20(5):055026. · 1.79 Impact Factor
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    ABSTRACT: A polymeric-based colorimetric gas sensor with its associated electronics targeting ammonia detection at low-cost and low-power is presented. The gas sensitive layer was inkjet printed on a plastic foil used as an optical waveguide. The planar configuration of the sensor makes it compatible with large scale fabrication techniques, such as roll-to-roll processes. Its power consumption and noise level were measured. The sensor exhibited a good sensitivity to ammonia with a theoretical limit of detection of 104 ppb in a constant operation mode. The power consumption was reduced to the sub-mW range when operating in pulsed mode. It foresees applications in the field of wireless systems, for environmental and safety monitoring.
    Micro Electro Mechanical Systems (MEMS), 2010 IEEE 23rd International Conference on; 02/2010
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    Jérôme Courbat, Danick Briand, Nico de Rooij
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    ABSTRACT: A generic method for the reverse processing of dry photoresist is proposed. The technique is based on the lamination of prepatterned polymeric structures on the pre-existing devices. The concept is illustrated with the encapsulation at the foil level of gas sensors made on plastic foil. This polymeric-based technique can be either applied on plastic foils but also on conventional substrates such as silicon or glass. It can be used when standard packaging techniques might not be suitable or when they can represent a significant cost. Using the lamination of a foil, the low-temperature and dry process presented here is compatible with large scale fabrication techniques, such as roll-to-roll processing, and aims at reducing the global fabrication cost of sensing devices made on plastic foil.
    01/2010;
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    01/2009;
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    ABSTRACT: Temperature, gas and humidity resistive/capacitive sensors on plastic substrates, suitable for mobile applications, like smart RFID tags, have been produced and investigated. The sensor concept is providing simple, versatile and low power solutions for temperature, humidity and gas detection. The device structure was devised together with the data evaluation strategies based on the latest generation ΣΔ analog (resistance and capacitance) to digital converters. The possibility of developing gas sensors on humidity sensitive substrates, having temperature corrected responses is demonstrated. The proposed sensor is aimed to evolve towards “flexible and full plastic” implementations.
    Sensors and Actuators B: Chemical. 01/2009;
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    ABSTRACT: We report on the realization of a low-cost polymeric optical waveguide made on a plastic foil and used for colorimetric gas detection. Low-temperature processes have been used for the realization of polymeric micro-mirrors and the depositions of the chemochromic reagent on PET foil. The planar waveguide configuration aims at improving the transducer sensitivity and simplifies its fabrication. Indeed, the device is currently produced by standard microfabrication techniques but its configuration and the materials involved make the sensor compatible with large scale and low-cost fabrication techniques. The operation of the optical transducer was applied to a colorimetric gas sensor and validated for the detection of ammonia.
    Procedia Chemistry. 01/2009;
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    ABSTRACT: We report on the design and fabrication of ultra-low power metal-oxide (MOX) gas sensors on plastic foils envisioning their fabrication at large scale and low cost. A complete sensor solution is presented including its packaging at the foil level and the driving/readout circuitry. The latter allowed the sensor to operate in pulsed temperature mode to reduce the power consumption in the sub-mW range. Gas measurements under CO, CH4 and NO2 have proven the proper operation of the sensor. These devices are being developed targeting wireless applications.
    01/2009;

Publication Stats

127 Citations
13.15 Total Impact Points

Institutions

  • 2012
    • Universität Luzern
      Luzern, Lucerne, Switzerland
  • 2009–2012
    • École Polytechnique Fédérale de Lausanne
      • • Institute of Microengineering
      • • Sensors, Actuators and Microsystems Laboratory
      Lausanne, Vaud, Switzerland
  • 2008
    • Université de Neuchâtel
      • Laboratoire Temps-Fréquence (LTF)
      Neuenburg, Neuchâtel, Switzerland
  • 2007
    • University of Tuebingen
      • Institute of Physical and Theoretical Chemistry
      Tübingen, Baden-Wuerttemberg, Germany
    • École Nationale Supérieure des Mines de Saint-Étienne
      Saint-Étienne, Rhône-Alpes, France