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Zarnik M.S.,HYB D.o.o. | Zarnik M.S.,Hipot Rr | Zarnik M.S.,Jozef Stefan Institute | Belavic D.,Hipot Rr | Belavic D.,Jozef Stefan Institute
Sensors and Actuators, A: Physical | Year: 2014

Glass-containing ceramics can be susceptible to stress corrosion in the presence of humidity. Furthermore, static loading in such conditions may adversely affect their flexural strength. Such degradation can critically affect the reliability of functional ceramic systems operating under mechanical loads. This experimental study examines the operation of pressure sensors made from low temperature cofired ceramics (LTCC). The sensors were subjected to a cyclic pressure loading in deionized water. The effect of this accelerated ageing was evaluated by comparing the changes in the offset voltage and the burst pressure to the characteristics of the sensors aged/loaded under normal ambient conditions. The results showed a satisfactory long-term stability of the sensors after one million full-scale (FS) pressure cycles as well as the sensors subjected to 10,000 overload pressure cycles (5× FS). As expected, the presence of water slightly reduces the burst pressure, but does not critically degrade the performance of the sensors or their reliability. © 2014 Elsevier B.V. All rights reserved.

Santo Zarnik M.,Hipot Rr | Belavic D.,Hipot Rr
Radioengineering | Year: 2012

The effect of the humidity of the surrounding atmosphere on the characteristics of capacitive structuresis a known problem for capacitive gas-pressure sensors. However, the use of a differential mode of operation can provide a good solution-only the manufacturing of the ceramic structures with the appropriate pairs of capacitive sensing elements remains a major challenge. In order to find a compromise solution, the effect of the humid atmosphere and the moisture on the exterior of an LTCC-based capacitive pressure sensor was inspected closely through experimental and numerical analyses of various situations.

Zarnik M.S.,Hipot Rr | Zarnik M.S.,Jozef Stefan Institute | Belavic D.,Hipot Rr | Macek S.,Jozef Stefan Institute
Sensors and Actuators, A: Physical | Year: 2010

Ceramic pressure sensors were investigated as candidates for applications in the low-pressure range. The use of low-temperature co-fired ceramic (LTCC) materials and technology combines many advantageous features for pressure sensors: the relative ease of producing three-dimensional structures, the availability of relatively thin sheets, and the relatively low Young's moduli together with a still reasonable mechanical strength. This makes it possible to achieve a higher resolution in comparison to the most commonly used Al2O3-based ceramic pressure sensors and an appropriate miniaturisation. However, special precautions are needed when designing a sensor for applications at very low pressures, starting from the selection of the materials and the processing parameters to the realization of the package. In this paper we present a few details of a case study of an LTCC-based piezoresistive sensor designed for the measurement of air or liquid pressures lower than 3 kPa. A series of test sensors was manufactured and characterised. Among the experimental tests the numerical analyses were included to show the trends and help reveal the impact of some of the design parameters. The essential sensor characteristics, i.e., the sensitivity, the warm-up drift and the offset voltage stability are discussed. The numerical and experimental results showed that the characteristics are favourable for applications in the pressure range below 10 kPa. © 2010 Elsevier B.V. All rights reserved.

Zarnik M.S.,Hipot Rr | Zarnik M.S.,Jozef Stefan Institute | Belavic D.,Hipot Rr | Belavic D.,Jozef Stefan Institute
Metrology and Measurement Systems | Year: 2012

LTCC-based pressure sensors are promising candidates for wet-wet applications in which the effect of the surrounding media on the sensor's characteristics is of key importance. The effect of humidity on the sensor's stability can be a problem, particularly in the case of capacitive sensors. A differential mode of operation can be a good solution, but manufacturing the appropriate sensing capacitors remains a major challenge. In the case of piezoresistive sensors the influence of humidity is less critical, but it still should be considered as an important parameter when designing sensors for low-pressure ranges. In this paper we discuss the stability of the sensors' offset characteristics, which was inspected closely using experimental and numerical analyses. © 2012 Polish Academy of Sciences. All rights reserved.

Pohar A.,Slovenian National Institute of Chemistry | Belavic D.,Hipot Rr | Dolanc G.,Jozef Stefan Institute | Hocevar S.,Slovenian National Institute of Chemistry
Journal of Power Sources | Year: 2014

Methanol decomposition on Pt/CeO2/ZrO2 catalyst is studied inside a packed bed microreactor in the temperature range of 300-380 C. The microreactor is fabricated using low-temperature co-fired ceramic (LTCC) technology, which is well suited for the production of relatively complex three-dimensional structures. It is packed with 2 wt% Pt-CeO2 catalyst, which is deposited onto ZrO2 spherical particles. A 1D mathematical model, which incorporates diffusion, convection and mass transfer through the boundary layer to the catalyst particles, as well as a 3D computational fluid dynamics model, are developed to describe the methanol decomposition process inside the packed bed. The microreactor exhibits reliable operation and no catalyst deactivation was observed during three months of experimentation. A comparison between the 1D mathematical model and the 3D model, considering the full 3D geometry of the microreactor is made and the differences between the models are identified and evaluated. © 2014 Elsevier B.V. All rights reserved.

Zarnik M.S.,Hipot Rr | Mozek M.,University of Ljubljana | Macek S.,Jozef Stefan Institute | Belavic D.,Hipot Rr
Informacije MIDEM | Year: 2010

A capacitive pressure sensor, fabricated using low-tempeature cofired ceramic (LTCC) materials and technology was considered for an application in a wireless sensor system. LTCC technology is inherently efficient for 3D structuring and exhibits good dimensional definition and stability, appropriate material flexibility (higher than the commonly used alumina), good chemical resistance, and low moisture absorption, which makes it appropriate for a wide range of sensor applications, even in some extreme conditions and harsh environments. However, very often in such applications, remote control and operation in a low power-consumption mode are required. In order to meet such demands, electronics for signal processing and power managing, based on a capacitance-to-digital conversion, were realised by using an Analog Devices AD7746. A sensor characterization system with the corresponding software for an evaluation of the sensor's nonlinearity and temperature sensitivity is presented. The typical characteristics of the capacitive sensing elements were as follows: a sensitivity of 1.7 fF/mbar, a temperature dependence of 9 fF/°C and a temperature dependence of the sensitivity of less than 2 aF/mbar/°C. The digital temperature compensation was performed with a two-dimensional rational polynomial approximation, resulting in a less than 0.4% FS temperature error in the compensation range 10 °C to 75 °C.

Zarnik M.S.,Hipot Rr | Zarnik M.S.,Jozef Stefan Institute | Sedlakova V.,Brno University of Technology | Belavic D.,Hipot Rr | And 4 more authors.
Sensors and Actuators, A: Physical | Year: 2013

In this paper we present the results of an investigation of the long-term stability of piezoresistive LTCC-based pressure sensors with the main emphasis on the effects of accelerated ageing. Noise spectroscopy was considered as a possible method for predicting the stability of the sensors' characteristics. The experiments showed that the stability of the sensors' offset voltage clearly relates to the low-frequency noise of the output signal: a lower noise level corresponds to a better long-term stability. An additional important finding is that the accelerated ageing that was carried out through the pressure cycling does not cause any significant increase in the sensors' signal noise. This result suggests that the performed pressure loadings do not introduce some critical cracks in the thick-film sensing resistors, which may adversely influence the sensors' stability. Moreover, the experiments revealed that the poor stability of the sensors, which was manifested in noticeable changes in the offset voltage and the sensitivity of some sensors after the overload pressure cycles, comes from defects that are not detectable using typical characterisation measurements and long-term stability tests. Since the unstable sensors always have a higher low-frequency noise of the output voltage in comparison with the stable sensors, the noise measurements can be described as a successful pre-screening test for a relatively quick assessment of the sensors' long-term stability. © 2013 Elsevier B.V. All rights reserved.

Agency: Cordis | Branch: FP7 | Program: CP-FP | Phase: NMP.2011.1.2-3 | Award Amount: 4.85M | Year: 2012

The main objective of the CERAMPOL project is to achieve a new generation of smart and low-fouling nanostructured membranes based on ceramic and polymeric materials with enhanced affinity to heavy metals and drugs. CERAMPOL will contribute in solving issues related to waste water in metallurgic and pharmaceutical industries/hospital respectively. Moreover, by reducing the concentration of highly toxic contaminants in the water supplies, lakes, rivers, and streams, the new filtration technology developed in the CERAMPOL project will mitigate the risk to humans health and the environment such as bioaccumulation of heavy metals, the emergence of multidrug resistance organisms, chronic toxicity, and metal-related diseases. The new filters will be prepared by innovative processes such as electrospinning, sol-gel, coating processes for obtaining multi-layered membranes possessing several key properties such as: antifouling; self-cleaning; selective filtration of antibiotics and heavy metals. Specifically, the multi-layered membranes will composed of three functional parts CERAMPOL functional parts: an anti-fouling pre-filter based on polymeric nanofibers, a cleaning system based on piezoelectric materials, and a highly selective nanostructured ceramic membrane. The new filters will be scaled up at semi industrial level for in-situ water treatments in foundry, pharmaceutical and hospital effluents. The benefits of such technology will be fully characterized in terms of water filtration efficiency and economic and environmental impacts. Complete technological and economical viability assessments of the CERAMPOL technology will be carried out by the industrial partners. Environmental impact caused by the new filtration technology will be fully assessed in order to highlight benefits in terms of water preservation and recovering.

PubMed | Jozef Stefan Institute, Hipot Rr and Hyb d.o.o.
Type: Journal Article | Journal: Sensors (Basel, Switzerland) | Year: 2015

An exploratory study of the impact of housing on the characteristics of a low-temperature co-fired ceramic (LTCC) pressure sensor is presented. The ceramic sensor structure is sealed in a plastic housing. This may have non-negligible effect on the final characteristics and should be considered in the early design phase. The manufacturability issue mainly concerning the selection of available housing and the most appropriate materials was considered with respect to different requirements for low and high pressure ranges of operation. Numerical predictions showed the trends and helped reveal the critical design parameters. Proper selection of the adhesive material remains an essential issue. Curing of the epoxy adhesive may introduce non-negligible residual stresses, which considerably influence the sensors characteristics.

Marghescu C.,Polytechnic University of Bucharest | Ionescu C.,Polytechnic University of Bucharest | Svasta P.,Polytechnic University of Bucharest | Zarnik M.S.,Hipot Rr | Belavic D.,Hipot Rr
ISSE 2010 - 33rd International Spring Seminar on Electronics Technology: Polymer Electronics and Nanotechnologies: Towards System Integration - Conference Proceedings | Year: 2010

Although the pressure sensor market is dominated by silicon based sensors, in recent years ceramic based sensors have proved interesting and have been increasingly researched due to their material properties which qualify them for use in harsh environments. This paper describes the use of finite element analysis (FEA) to determine the functioning of a diaphragm-type ceramic capacitive pressure sensor starting from mechanical pressure and obtaining the output signal in form of an electrical capacitance. The capability of the software (Ansys/Multiphysics) to realize multi-field analysis will be used here in a very intensive way. Of major concern is the possibility to anticipate the influence of different liquid media on this category of pressure sensors developed using LTCC (Low Temperature Co-fired Ceramic). © 2010 IEEE.

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