Publications by Peter Ryser | EPFL Graph Search

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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

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

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

We consider the problem of electron transport in segregated conductor-insulator composites in which the conducting particles are connected to all others via tunneling conductances, thus forming a global tunneling-connected resistor network. Segregation is ...

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.

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.

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 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

The connectedness percolation threshold (eta(c)) and critical coordination number (Z(c)) of systems of penetrable spherocylinders characterized by a length polydispersity are studied by way of Monte Carlo simulations for several aspect ratio distributions. ...

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

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Firing, quenching and annealing studies on thick-film resistors

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

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

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

Tunneling and percolation transport regimes in segregated composites

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

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

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

Critical behaviour of the piezoresistive response in RuO2-glass composites

Quasiuniversal Connectedness Percolation of Polydisperse Rod Systems

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