Publications by Thomas Maeder | EPFL Graph Search

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We propose an SMD (surface mount device) sensor in LTCC (low-temperature co-fired ceramic) technology specially designed for standard industrial compressed air. It combines the measurement of pressure, flow, and temperature, with its integrated signal conditioning electronics. Such a sensor can be mounted on an integrated electro-fluidic platform like a standard component using surface mount technology, obviating the need for both wires and tubes.

Low Temperature Co-fired Ceramics (LTCC) is one of the microelectronic techniques. This technology was initially developed as an alternative to Printed Circuit Boards (PCB) and classical thick-film technology, and it has found application in the fabricatio ...

In this work, we have modified a low-temperature thick-film system previously developed for aluminium and aluminium alloy substrates in order to adapt it to ferritic and austenitic stainless steel, and glass substrates, which, unlike the common alumina substrate material, cannot usually be exposed to the standard high-temperature 850 °C thick-film firing cycle. Such substrate materials are useful for several important applications: high-response piezoresistive thick-film sensors (steel), displays (glass), h

Piezoresistive pressure sensors using classical deformable structures such as membranes progressively run into difficulties at very high pressures (above 1 to 2 kbar), due to the decreasing ratio between the available sensing strain on the outer membrane surface and the maximal materials strain experienced on the pressurised side. Therefore, a novel "isostatic" pressure sensor concept, whereby the sensing element is immersed in the pressure fluid, has been developed. This method in principle allows the meas

We evaluate the percolation threshold values for a realistic model of continuum segregated systems, where random spherical inclusions forbid the percolating objects, modellized by hard-core spherical particles surrounded by penetrable shells, to occupy lar ...

LTCC technology continues to be an attractive option for fabrication of sensors, sensor packages and complex micro-systems. The objective of this work is to present LTCC sensors developed by CSEM Brasil with a focus on capacitive type wireless soil moisture sensor (SMS) for precision farming that is capable to measure soil moisture in real time and transmit the data to 80 m distance (line of sight). The sensor is constructed from 4 functional blocks: PCB base including the capacitive electrodes, LTCC block

We present a compact frequency-stabilized laser system locked to the Rubidium absorption line of a micro-fabricated reference cell. A printed circuit board (PCB) is used to carry all the components and part of the electronics, and low-temperature co-fired ...

We re-analyse earlier measurements of resistance R and piezoresistance K in RuO2-based thick-film resistors (TFRs). The percolating nature of transport in these systems is well accounted by values of the transport exponent t larger than its universal value t ≈ 2.0. Furthermore, we show that the RuO2 volume fraction dependence of the piezoresistance data fit well with a logarithmically divergence at the percolation threshold. We argue that the universality breakdown and diverging piezoresistive response coul

In situ reactively sputter deposited, 300-nm-thick Pb(Zrx,Ti1-x)O3 thin films were investigated as a function of composition, texture, and different electrodes (Pt,RuO2). X-ray diffraction analysis, ferroelectric, dielectric, and piezoelectric measurements were carried out. While for dielectric properties bulklike contributions from lattice as well as from domains are observed, domain wall contributions to piezoelectric properties are very much reduced in the morphotropic phase boundary (MPB) region. Permit

We investigate in this work the formulation of composite resistive pastes based on epoxy resins and graphite for micro-heater manufacturing via thick-film technology. These resistive pastes are designed for screen-printing onto a printed circuit board (PCB ...

In this work, we present and analyse the flow-sensing part of a recently-developed multisensor in LTCC (low- temperature co-fired ceramic) technology; this device integrates flow / pressure / temperature sensing and is designed for diagnostics monitoring o ...

A vast class of disordered conducting-insulating compounds close to the percolation threshold is characterized by nonuniversal values of transport critical exponent t, in disagreement with the standard theory of percolation which predicts t ...

A vast class of disordered conducting-insulating compounds close to the percolation threshold is characterized by nonuniversal values of transport critical exponents. The lack of universality implies that critical indexes may depend on material properties such as microstructure, composition etc., and that in principle they can be influenced by suitable applied perturbations leading to important informations about the origin of nonuniversality. Here we show that RuO2-glass compounds can have nonuniversal val

Thick-film and LTCC (Low Temperature Cofired Ceramic) technologies find increasing use in meso-scale sensors, actuators and related devices that feature excellent dimensional, thermal and chemical stability at moderate cost. While several materials and processes allow fabrication of structures such as channels, membranes and relatively short bridges, obtaining slender bridges and cantilevers with good shape control for applications such as microforce sensors has hitherto remained a challenging task. This wo

This work addresses the issue of attaching the force-centring part (a round ball) to the load cell of a force sensor, a piezoresistive thick-film Wheatstone bridge deposited onto a ceramic cantilever. As the current soldering process requires expensive met ...

Thick film resistors are prepared as pastes, which are screen-printed and fired on dielectric substrates such as alumina and widely used in hybrid circuits. The final resistor properties are mostly influenced by the firing conditions and the interactions between the elements in the substrate and the resistor. In this study, conductor – resistor (PTC thermistor) pairs of selected compositions of different chemical origin are post fired on low temperature co-fired ceramic (LTCC) and alumina substrates, the la

The purpose of this paper is to demonstrate sensors and structures fabricated using the LTCC technology, which has been addressed and employed increasingly as a smart packaging approach for several applications. The focus will be on inclination and cantile ...

A novel formulation for thick-film graphite sacrificial pastes is studied in this paper. It is composed of coarse graphite powder (grain size: 25 μm), dispersed in a vehicle consisting of polyvinyl alcohol (PVA) dissolved in a propylene glycol (PG)–glycero ...

Ceramic hotplates using classical thick-film technology or low-temperature cofired ceramic (LTCC) find a wide range of potential applications: infrared sources, fuel cell components and packaging, microreactors and sensors. This versatility is made possible by the relative ease of structuration and moderate cost achievable with these technologies. However, mass production of simple, low-cost sensors and disposable samples for materials characterisation requires very simple devices. In this work, we therefor

LTCC (Low-Temperature Cofired Ceramic) has attracted considerable interest as a material for sensors and microfluidic circuits, for which dimensional accuracy is essential. The irregular shrinkage behaviour of LTCC tapes must be taken into account when designing devices. Furthermore the shrinkage observed in practice can be different than that given by the manufacturers. This study analyses and models with Design of Experiments the shrinkage of DuPont GreenTapeTM 951AX LTCC foils. Unlike most past studies,

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SMD pressure and flow sensor for compressed air in LTCC technology with integrated electronics

Overview on low temperature co-fired ceramic sensors

Integrated thick-film hybrid microelectronics applied on different material substrates

LTCC ultra high isostatic pressure sensors

Optimal percolation of disordered segregated composites

Low-temperature co-fired ceramic (LTCC) technology for development of sensors for emerging applications

A miniature frequency-stabilized VCSEL system emitting at 795nm based on LTCC modules

Critical behaviour of the piezoresistive response in RuO2-glass composites

Domain and lattice contributions to dielectric and piezoelectric properties of Pb(Zr x , Ti 1− x )O 3 thin films as a function of composition

Formulation of composite resistive pastes for fabrication of micro-heaters

Integrated SMD pressure/flow/temperature multisensor for compressed air in LTCC technology: Thermal flow and temperature sensing

Tunneling-percolation origin of nonuniversality: Theory and experiments

Strain dependence of transport critical exponent in RuO2-glass systems

Structuration of thin bridge and cantilever structures in thick-film technology using mineral sacrificial materials

Optimisation of industrial production of low-force sensors – adhesive bonding of force-centring ball

Effects of firing conditions on thick-film PTC thermistor characteristics in LTCC technology

Structuration and Fabrication of Sensors Based on LTCC (Low Temperature Co-fired Ceramic) Technology

Structuration of the low temperature co-fired ceramics (LTCC) using novel sacrificial graphite paste with PVA–propylene glycol–glycerol–water vehicle

Ceramic cantilever hotplates for devices and testing platforms

Influence of lamination parameters on LTCC shrinkage under unconstrained sintering