In this work the design aspects of a piezoelectric-based resonance ceramic pressure sensor made using low-temperature co-fired ceramic (LTCC) technology and designed for high-temperature applications is presented. The basic pressure-sensor structure consists of a circular, edge-clamped, deformable diaphragm that is bonded to a ring, which is part of the rigid ceramic structure. The resonance pressure sensor has an additional element – a piezoelectric actuator – for stimulating oscillation of the diaphragm in the resonance-frequency mode. The natural resonance frequency is dependent on the diaphragm construction (i.e., its materials and geometry) and on the actuator. This resonance frequency then changes due to the static deflection of the diaphragm caused by the applied pressure. The frequency shift is used as the output signal of the piezoelectric resonance pressure sensor and makes it possible to measure the static pressure. The characteristics of the pressure sensor also depend on the temperature, i.e., the temperature affects both the ceramic structure (its material and geometry) and the properties of the actuator. This work is focused on the ceramic structure, while the actuator will be investigated later.

VTT Technical Research Centre of Finland Ltd. has developed and utilized Low Temperature Co-fired Ceramic (LTCC) technology for about 25 years. This paper presents our activities related to photonics and millimetre-waves, including also a relevant literature survey. First a short summary of the technology is given. Especially, the unique features of LTCC technology are described in more details. In addition, several examples have been given to show the validity of LTCC technology in these high-performance fields.

The paper presents general information on LTCC materials, manufacturing processes and properties of fired modules. A Multichip Module package has been the main application of Low Temperature Cofired Ceramic (LTCC) technology. Recently, this technology is also used for production of sensors, actuators and microsystems. The research and development on the LTCC sensors and microsystems carried out in the Laboratory of Thick Film Microsystems at Wroclaw University of Technology are presented. LTCC microfluidic system is described in detail. Moreover, a short information is given on other LTCC applications .

The numerical investigation of the mixing process in complex geometry micromixers, as a function of various inlet conditions and various micromixer vibrations, was performed. The examined devices were two-dimensional (2D) and three-dimensional (3D) types of serpentine micromixers with two inlets. Entering fluids were perturbed with a wide range of the frequency (0 - 50 Hz) of pulsations. Additionally, mixing fluids also entered in the same or opposite phase of pulsations. The performed numerical calculations were 3D to capture the proximity of all the walls, which has a substantial influence on microchannel flow. The geometry of the 3D type serpentine micromixer corresponded to the physically existing device, characterised by excellent mixing properties but also a challenging production process (Malecha et al., 2009). It was shown that low-frequency perturbations could improve the average mixing efficiency of the 2D micromixer by only about 2% and additionally led to a disadvantageously non-uniform mixture quality in time. It was also shown that high-frequency mixing could level these fluctuations and more significantly improve the mixing quality. In the second part of the paper a faster and simplified method of evaluation of mixing quality was introduced. This method was based on calculating the length of the contact interface between mixing fluids. It was used to evaluate the 2D type serpentine micromixer performance under various types of vibrations and under a wide range of vibration frequencies.

In this paper a design of millimeter-wave six-port device for LTCC (Low Temperature Cofired Ceramic) technology is presented. Furthermore, problems with implementation of the project taking into account requirements of LTCC technology are discussed.

Millimeter-wave (mm-wave) transmitters are often fabricated using advanced technology and require a sophisticated manufacturing facility. Access to such technologies is often very limited and difficult to gain particularly at the initial stage of research. Therefore, to increase the accessibility of mm-wave transmitters, this study proposes a design that can be assembled in a standard microwave laboratory from commercially available or externally ordered components. The transmitter demonstrated in this paper operates above 100 GHz and is based on a lowtemperature co-fired ceramic board in which the antenna array, microstrip lines, and power-supply lines are fabricated in a single process. Different technologies are used to assemble the module, e.g., wire-bonding, soldering, and wax adhesion. Advantages and disadvantages of the proposed design are given based on experimental evaluation of the prototype. Although the performance of the developed transmitter is not as good as that of the similar modules available in the recent literature, the results confirm the feasibility of a mm-wave transmitter that is assembled without employing advanced technologies and superior machinery.

Investigations on integration of optoelectronic components with LTCC (low temperature co-fired ceramics) microfluidic module are presented. Design, fabrication and characterization of the ceramic structure for optical absorbance is described as well. The geometry of the microfluidic channels has been designed according to results of the CFD (computational fluid dynamics) analysis. A fabricated LTCC-based microfluidic module consists of an U-shaped microchannel, two optical fibers and integrated light source (light emitting diode) and photodetector (light-to-voltage converter). Properties of the fabricated microfluidic system have been investigated experimentally. Several concentrations of potassium permanganate (KMnO4) in water were used for absorbance/transmittance measurements. The test has shown a linear detection range for various concentrations of heavy metal ions in distilled water. The fabricated microfluidic structure is found to be a very useful system in chemical analysis.

This paper presents the concept and modern technological approach to the fabrication of discrete, integrated and integral micropassives. The role of these components in modern electronic circuits is discussed too. The material, technological and constructional solutions and their relation with electrical and stability properties are analyzed in details for linear and nonlinear microresistors made and characterized at the Faculty of Microsystem Technology, Wrocław University of Technology.