Publications de Thomas Maeder | EPFL Graph Search

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In this work, we study in detail the sensing characteristics of piezoresistive force sensors based on structured LTCC (Low Temperature Co-fired Ceramic) cantilevers carrying a thick-film piezoresistive bridge. These devices show much improved sensitivity compared to classical alumina-based devices, but may exhibit abnormally large signal and drift, which indicates the presence of structural defects originating from fabrication issues or deleterious interactions between materials. To eliminate these effects,

We examine, in this work, the integration and high-strain response of piezoresistive thick-film resistors on titanium and titanium alloy, as compared with ferritic stainless steel and the standard alumina substrates. In general, titanium and its alloys are relatively ill suited for use as a thick-film substrate using the standard 850 °C firing process, because of its low oxidation resistance and tendency to dissolve oxygen. This problem can be alleviated by applying suitable thick-film glassy protection lay

For micromechanical applications, piezoelectric PbZrTO3 (PZT) thin films have been deposited on metallised Si3N4/SiO2 layers on Si wafers. Films with compositions near the morphotropic phase boundary (x=0.53) were prepared at 600°C using a multitarget, in- ...

We have designed and fabricated a low-range (ca. 100 mN) thick-film piezoresistive force sensor with a cantilever beam fabricated in LTCC (Low Temperature Co-fired Ceramic). The beam was soldered onto a standard thick-film 25.4 x 12.7 mm signal conditioning base [1]. Switching from a classical Al2O3-based thick-film beam to LTCC allows design of a 3D structured beam with increased sensitivity of the piezoresistive bridge, yet largely conserved strength and stiffness. Another advantage of LTCC compared to al

In conductor-insulator composites in which the conducting particles are dispersed in an insulating continuous matrix the electrical connectedness is established by interparticle quantum tunneling. A recent formulation of the transport problem in these kind ...

Ligament balancing in total knee arthroplasty may have an important influence on joint stability and prosthesis lifetime. In order to provide quantitative information and assistance during ligament balancing, a device that intraoperatively measures knee jo ...

In this work, we aim to understand the firing behaviour of three representative thick-film resistor compositions used in force and pressure sensors. The dependence of the materials' microstructure and properties (sheet resistance and its temperature coefficient, gauge factor) is studied as a function of firing temperature and time, and cooling rate (furnace or quench). The stability of the properties is assessed by annealing at intermediate temperatures (100 and 250 °C). Microscopic and structural analysis

An innovative method for filling and sealing the reference cell for a Rubidium (Rb) integrated atomic clock is presented. We used a simple, low-temperature solder sealing technique for producing mini-cells of the size of 12 x 10 x 2 mm, suitable for Rb miniature atomic clocks. The cell is made by two glass slides acting as the top and bottom walls, joined by a solder ring acting as the sidewall. In the frame of this research, we also developed a safe and convenient method for easily handling Rb: the alkali

Ce document décrit l'ajustement passif de l'embase MilliNewton, version E, ainsi que les résultats obtenus sur 5 substrats, avant ajustement, après ajustement et après recuit ultérieur de stabilisation. La correction des défauts de l'embase D permet notamment la sérigraphie plus mince et avec des paramètres plus raisonnables de la composition résistive 100 kOhm ESL 3915. Le problème de sa grande variation en valeur subsiste, mais est maintenant sous contrôle. La diminution d'épaisseur de cette composition p

In this work a prototype of micro force sensor of range μN...mN is presented. Instead of the traditional piezoresistive strain sensing through thick-film resistors used for higher forces, a more effective principle is used: measurement of beam displacement ...

The goal of this project was to develop low-firing thick-film materials systems for the fabrication of piezoresistive sensors on special steels, for the fabrication of instrumented medical devices. To this end, a series of individual thick-film materials and complete systems, based on lead borosilicate glasses, were developed and extensively characterised. These studies allowed us to formulate an optimised system firing at 625°C and applicable to austenitic, ferritic and martensitic steels. The functionalit

In this work, the properties (sheet-resistance, temperature coefficient and piezoresistance / gauge factor) and stability of thick-film resistors with low firing temperatures (525...650°C) are studied. To this end, two low-melting lead borosilicate glass c ...

Drop-on-Demand Inkjet printing can be used as an effective technique to deposit the sensing layer in chemical sensors. However, formulation of inks containing functional materials remains challenging due to rheological constraints imposed by the inkjet printer. Here, we show a systematic process to formulate and print functional inks containing polymer and carbon black (CB) particles. The functional ink is used for sensing different analytes considering the polarity of the polymer1,2. We formulated inks con

This document concerns the deviation of the output of MilliNewton and CentoNewton force sensors from ideal ratiometric behaviour. These sensors nominally operate from a single +5 V supply voltage and, as they have no voltage regulator, their output response should be ideally "ratiometric", i.e. proportional to supply voltage, within the operating range of the used amplifier chip. However, due to the amplifier characteristics (nonlinear offset), a substantial deviation of the sensor offset (zero-load output)

We present a multisensor designed for industrial compressed air diagnostics and combining the measurement of pressure, flow, and temperature, integrated with the corresponding signal conditioning electronics in a single low-temperature co-fired ceramic (LTCC) package. The developed sensor may be soldered onto an integrated electro-fluidic platform by using standard surface mount device (SMD) technology, e.g., as a standard electronic component would be on a printed circuit board, obviating the need for both

Low-temperature cofired ceramic (LTCC) combines many advantageous features for low-range (force & pressure) piezoresistive sensors: ease of 3D structuration, availability of very thin sheets, low elastic modulus and yet reasonable mechanical strength. This ...

Ease of fabrication and design flexibility are two attractive features of low temperature co-fired ceramics (LTCC) technology for fabrication of complex micro-fluidic devices. Such structures are designed and processed using different shaping methods, the extent and complexity of which depends on the final device specifications (dimensions, mechanical and functional properties). In this work, we propose a sacrificial layer method based on carbon-black paste, which burns out during the LTCC firing stage. The

This work presents the continued development of an autonomous portable system for measuring the Wobbe number (calorific content) of gases for the purpose of determining the quality of natural gas. Past research has shown the Wobbe number can be determined if the dynamic viscosity is known. The sensor described here operates on this principle and is essentially a gas viscometer. The sensing components are integrated into single low temperature co-fired ceramic (LTCC) device making the sensor compact and low

In this work, we propose an SMD (surface mount device) pressure sensor in LTCC technology specially designed for standard industrial compressed air. It combines the measurement of pressure and temperature, with its integrated signal conditioning electronics for linearization, adjustment and temperature compensation. For the first time, 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.

Thomas Maeder

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Dispensing and Hermetic Sealing Rb in a Miniature Reference Cell for Integrated Atomic Clocks

Signal Stability of LTCC Cantilever Force Sensors

High-strain response of piezoresistive thick-film resistors on titanium alloy substrates

Pb(Zr,Ti)O3 thin films by in-situ reactive sputtering on micromachined membranes for micromechanical applications

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

Transport properties of nonhomogeneous segregated composites

Ligament balancing in TKA: Evaluation of a force-sensing device and the influence of patellar eversion and ligament release

Firing, quenching and annealing studies on thick-film resistors

Dispensing and hermetic sealing Rb in a miniature reference cell for integrated atomic clocks

MilliNewton – Ajustement passif de l'embase version E

Capacitive micro force sensors manufactured with mineral sacrificial layers

Load sensing surgical instruments - Development and characterisation of low firing thick-film materials systems for medical steels

Properties and stability of thick-film resistors with low processing temperatures - effect of composition and processing parameters

Drop-on-Demand Inkjet Printing of Functional Composites

T0003 / MilliNewton & CentoNewton force sensors / Deviation from ratiometric behaviour

Integrated LTCC pressure / flow / temperature multisensor for compressed air diagnostics

Design and processing of low-range piezoresistive LTCC force sensors

Fabrication of LTCC Micro-fluidic Devices Using Sacrificial Carbon Layers

Portable LTCC gas viscometer for determining Wobbe number

SMD pressure and flow sensors for industrial compressed air in LTCC technology