Publications by Peter Ryser | EPFL Graph Search

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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,

The processing and application of graphite powder-based sacrificial layer for fabrication of microfluidic structures in LTCC is described. Such layers are produced as pastes, which are screen-printed in LTCC sheets to avoid sagging, by supporting closed, t ...

Thick-film resistors (TFRs) consist of a percolating network of conducting oxide nanoparticlesdispersed in an insulating glassy matrix, whose resistive properties are dominated by quantumtunneling across insulating layers separating adjacent conducting grains. Tunneling processes are at the origin of the high sensitivity of the TFRs resistances to applied strains. We have measuredtransport and piezoresistive response for different RuO2-based TFRs as a function of metallic concentration x and RuO 2 grain siz

We investigate the tunneling-percolation mechanism of DC transport nonuniversality for conducting particles of diameter Φ placed in series within the bonds of length Lof a regular lattice model. When L/Φ→∞ the resulting bond conductance distribution functi ...

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. The resistive paste is first screen-printed onto a printed circuit board (PCB) substrate, and then coated with expandable polydimethylsiloxane (PDMS), a composite based on an elastomeric matrix and expandable microspheres, resulting into one-shot thermal actuators allowing pumping and sealing in microfluidic devices. The resistive paste must t

Force and pressure sensors based on the piezoresistive properties of thickfilm resistors are widely used due to their reliability, simplicity and lowcost. Recently, the introduction of low-temperature co-fired ceramic(LTCC) substrates has allowed further increases in miniaturisation and integration, while new high-strength ceramic substrates such as zirconia- toughened alumina (ZTA) has enabled better sensor response.However, the materials' properties are still insufficiently characterised for sensor applic

We propose a model of transport in thick-film resistors which naturally explains the observed nonuniversal values of the conductance exponent t extracted in the vicinity of the percolation transition. Essential ingredients of the model are the segregated microstructure typical of thick-film resistors and tunneling between the conducting grains. Nonuniversality sets in as a consequence of wide distribution of interparticle tunneling distances. © 2003 American Institute of Physics.

An active implantable chemico-rheological sensor including control electronics, a Digital Signal Processor (DSP) and an RF transceiver has been demonstrated. The ultra-low power system architecture achieves an energy per viscosity measurement of only 16.6mJ of which 56% are dedicated to the micro-rheometer, 40% to the transceiver, and 4% to the DSP. Four coins batteries with a capacity of 150J each (Energizer 376) enabled a life time of 28’500 cycles at 37°C. The System in Package (SiP) fits in a 8.4mm in d

LTCC (low temperature co-fired ceramic) technology has recently gained a remarkable application potential in sensors field. This can be ascribed to many advantages it offers: the ease of LTCC tape handling providing a great freedom in design and fabrication, feasible processing conditions bringing down the costs, excellent thermal and chemical resistance, and combination of electrical and mechanical functions in a reliable hermetic system. In scope of this, fabrication of an LTCC-based millinewton force sen

Ceramic technologies such as thick-film and LTCC (Low Temperature Cofired Ceramic) are excellent platforms for the fabrication of mesoscale devices such as sensors, actuators, microreactors and MEMS packaging. This work presents two alternative screen-prin ...

In this work, a novel sensor for measuring the viscosity of a gas, based on the combination of a heating cavity, a pressure sensor and a meander with a high resistance to flow, all integrated in low-temperature co-fired ceramic (LTCC) technology, is presented. This paper reports the design, thermal characterisation and modelling of the heater module in quasi-stationary operation. The performance of the heater is satisfactory, and good agreement between experimental and calculated thermal properties is found

The proof of concept of a continuously sensing affinity device based on the glucose-dependent viscosity of a sensitive solution containing dextran and Concanavalin A has been successfully demonstrated. The biosensor incorporates a piezoelectric diaphragm a ...

We show that the formation of a gel by conducting colloidal particles leads to a dramatic enhancement in bulk conductivity, due to interparticle electron tunneling, combining predictions from molecular-dynamics simulations with structural measurements in an experimental colloid system. Our results show how colloidal gelation can be used as a general route to huge enhancements of conductivity, and suggest a feasible way for developing cheap materials with novel properties and low metal content.

In this work, a low-temperature thick-film dielectric consisting of a high-lead low-temperature glass with a reactive nanoscale filler is characterised to enable deposition of thick-film electronics onto substrates such as glass and metals (steel, aluminium, brass, titanium) which cannot be exposed to the standard high-temperature 850 C thick-film firing cycle. The dielectric is stabilised by reaction of the filler with the lead in the glass. For a TiO2 filler, we get : PbO (glass) + TiO2 (filler) -> PbTiO3

Peter Ryser

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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

Processing of Graphite-Based Sacrificial Layer for Microfabrication of Low Temperature Co-fired Ceramics (LTCC)

Transport nonuniversality and critical behavior of the piezoresistive response in thick-film resistors

Apparent nonuniversality in finite segregated tunneling-percolaiton models

Formulation of composite resistive pastes for micro-heater manufacturing

Strength of ceramic substrates for piezoresistive thick-film sensor applications

A model of transport nonuniversality in thick-film resistors

Implantable ultra-low power DSP-based system for a miniature chemico-rheological biosensor

Fabrication and characterization of LTCC-based millinewton force sensor: influence of design and materials compatibility on device performance

Formulation and processing of screen-printing vehicles for sacrificial layers on thick-film and LTCC substrates

LTCC thermal gas viscometer – heater module

Novel chemico-mechanical approach towards long-term implantable glucose sensing

Enhanced tunneling conductivity induced by gelation of attractive colloids

Low-temperature thick-film dielectrics stabilised by reaction with a nanocrystalline powder