Publications by Thomas Maeder | EPFL Graph Search

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The continuing trend in the automotive and aviation industries to reduce complexity of electronic systems by removing cooling results in a need for high temperature electronics and associated packaging technologies. To ensure reliability over long periods of time the degradation of the packaging materials should be characterised. Epoxies show great promise as a reliable die attach solution for high temperature electronics due to their high bond strength, resistance to fatigue and chemical stability at tempe

The resistivity dependence on temperature of composite resistors made of carbon fillers dispersed in an organic matrix are known to be strongly affected by the matrix thermal expansion. High positive temperature coefficient (PTC) effects, i.e. essentially switching from resistive to quasi-insulating behaviour, can be caused by phase changes in the matrix and the assorted volume expansion, a behaviour that has been previously shown with both simple organic waxes (low temperatures) and semicrystalline polymer

A new system combining a microreactor and a microcalorimetric chip was investigated. The small size of the microreactor channel permits maintaining isothermal conditions necessary for the kinetic characterization of highly exothermic reactions. These conditions are not easily obtained in classical calorimetric systems. The degree of mixing in the microchannel, which plays an important role for the characterization of fast reactions, was determined experimentally using an iodate–iodide system and confirmed b

An anisotropic magnetorheological composite formed by dispersions of silver-covered magnetite microparticles (Fe3O4@Ag) in polydimethylsiloxane (PDMS) displaying electrical conduction only in one preferred direction is presented. A set-up for applying and ...

Piezoelectric thin films of PbZrxTi1-xO3 (PZT) on membranes are the subject of keen interest for the fabrication of micro-sensors and actuators. Piezoelectric activity of the PZT on Si-based membranes has been shown, and a micromotor has been demonstrated. Standard substrates are based on Si due to the good barrier properties of SiO2 and Si3N4 layers, which protect the Si against further oxidation. For some applications, however, such structures are not appropriate. For instance, thin metallic sheets, which

With growing public interest in portable electronics such as micro fuel cells, micro gas total analysis systems, and portable medical devices, the need for miniaturized air pumps with minimal electrical power consumption is on the rise. Thus, the development and downsizing of next-generation thermal transpiration gas pumps has been investigated intensively during the last decades. Such a system relies on a mesoporous membrane that generates a thermomolecular pressure gradient under the action of an applied

Ceramic technologies such as LTCC (Low Temperature Co-fired Ceramic) and thick-film are used widely in electronic circuits exposed to harsh environments, for applications in fields such as aerospace, automotive and energy exploration, where, owing to their ...

LTCC technology is based on sintering of multi-layered thick-film sheets (50-250 µm) or so-called green tapes, which are screen-printed with thick-film pastes such as conductors, resistors, etc. The terms low temperature and co-fired originate from the rel ...

We demonstrate the application of inkjet-printed near room-temperature chemiresistors composed of polymer-carbon black (CB) composites for detecting and classifying volatile organic compounds (VOC). Our results demonstrate that the printed sensors can sele ...

The motivation of this study is the need for fundamental understanding of the effects of processing conditions on the electrical properties of low- temperature co-fired ceramic (LTCC) tapes, those screen printed with commercial thick-film pastes of electro ...

Micro‐solid oxide fuel cell (micro‐SOFC) systems are predicted to have a high energy density and specific energy and are potential power sources for portable electronic devices. A micro‐SOFC system is under development in the frame of the ONEBAT project [1‐3]. In this presentation, we report on the fabrication and characterization of a sub‐system assembly consisting of a startup heater and a micro‐reformer bonded to a Si chip with electrochemically‐active micro‐SOFC membranes. A functional carrier including

We noted that the tunneling-percolation framework is quite well understood at the extreme cases of percolation-like and hopping-like behaviors but that the intermediate regime has not been previously discussed, in spite of its relevance to the intensively ...

Thick film deposition of conductive, dielectric and resistive pastes on ceramic membranes is a cost effective technique to manufacture piezoresistive pressure sensors. Thick-film resistors consist of a percolating network of conductive oxide nanoparticles dispersed in an insulating glassy matrix, the electrical properties of which depend on firing conditions and composition. Ceramic membranes are appropriate to withstand the firing temperatures of thick-film materials, which are about 850°C. However brittle

We investigate in the present work the fabrication of polymer-based micro-fluidic and micro-mechanical devices using sacrificial, resistive/conductive pastes, through a screen-printing process. An organic sacrificial paste is first screen-printed onto a substrate, the future opening in the structure existing where the paste lies (channels, cavities...). Then, a resistive paste based on thermosetting polymer resin and graphite is deposited onto the previous layer. Finally, the sacrificial paste is removed at

Micro-scale solid oxide fuel cell is a promising power generation technology for portable devices such as laptop, medical devices and personal electronics. One of the key goals in design of μ-SOFC systems is to use common hydrocarbon fuels such as propane/ ...

In spite of many advantages it offers for micro-electronic packaging, the low temperature co-fired ceramic (LTCC) technology has yet certain issues to be solved. Physical and chemical reactions, for instance, within and between the passive electronic compo ...

Thick-film materials are very advantageous for piezoresistive pressure and force sensors because of ease of processing, reliability and low cost. However, their applications are restricted because standard thick-film materials require processing temperatures around 850°C, which essentially restricts them to ceramic substrates. In this work, we examine the processing and properties of thick-film dielectric and resistor compositions designed to sinter at lower temperatures, making them compatible with high-st

Force and pressure sensors based on the piezoresistive properties of thick- film resistors have recently found wide application due to their low cost, reliability, and relatively good precision. Achieving high elastic mechanical strains is important to maximise the sensor response, and better substrates than the standard 96% alumina such as yttrium-stabilised zirconia (YSZ) and zirconia-toughened alumina (ZTA) have therefore been investigated in this work. The substrate materials were characterised with res

In this work, we investigate the piezoresistive response of epoxy–graphite composites. A resistive thick-film Wheatstone bridge is deposited by screen-printing onto a beam, a weight is then applied on the tip of the beam and the resulting electrical signal ...

We investigate in this work the fabrication of polymer fluidic and mechanical devices based on evaporable compounds as sacrificial layers using the screen-printing process. The combination of thermosetting polymer resins with evaporable compounds as sacrificial layers allows straightforward fabrication of polymer microfluidic and micromechanical devices. Channel, cavities and spacings are first defined by sacrificial material layers. This is followed by polymer resin deposition and polymerization / solvent

Thomas Maeder

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Characterisation of test vehicle for in-situ measurement of die attach thermal conductivity

Tuneable PTC effect in polymer-wax-carbon composite resistors

A microreactor-based system for the study of fast exothermic reactions in liquid phase: characterization of the system

Superparamagnetic anisotropic elastomer connectors exhibiting reversible magneto-piezoresistivity

Buffer electrodes for deposition of lead zirconium titanate films on metallic substrates

Dimensional and structural control of silica aerogel membranes for miniaturized motionless gas pumps

3D structuration of LTCC and related technologies for thermal management and microfluidic structures

Low temperature co-fired ceramic (LTCC) technology: general processing aspects and fabrication of 3-D structures for micro-fluidic devices

Printed Polymer Composite Sensors for Low-Power, Near Room-Temperature Detection and Classification of VOCS

Influence of processing and conduction materials on properties of co-fired resistors in LTCC structures

Micro-solid oxide fuel cells running on reformed hydrocarbon fuels

Solution of the tunneling-percolation problem in the nanocomposite regime

Development of pressure sensors by powder technology

Fabrication of polymer-based micro devices: formulation and study of the paste

A micro heater platform with fluid channels for testing micro-solid oxide fuel cell components

Investigation of Interactions Between Co-fired LTCC Components

Development of low-temperature thick-film materials for piezoresistive sensors

High-strength ceramic substrates for thick-film sensor applications

Piezoresistive effect in epoxy–graphite composites

Screen-printed polymer-based microfluidic and micromechanical devices based on evaporable compounds