Jan Macioszczyk

Microfluidical Microwave Reactor for Synthesis of Gold Nanoparticles

Microwave treatment can reduce the time of selected syntheses, for instance of gold nanoparticles (AuNPs), from several hours to a few minutes. We propose a microfluidic structure for enhancing the rate of chemical reactions using microwave energy. This reactor is designed to control microwave energy with much higher accuracy than in standard devices. Thanks to this, the influence of microwave irradiation on the rate of chemical reactions can be investigated. The reactor consists of a transmission line surrounded by ground metallization. In order to deliver microwave energy to the fluid under test efficiently, matching networks are used and optimized by means of numerical methods. The monolithic device is fabricated in the low temperature co-fired ceramics (LTCC) technology. This material exhibits excellent microwave performance and is resistant to many chemical substances as well as high temperatures. Fabrication of the devices is described in detail. Measurements of microwave parameters are performed and differences between simulation and experiment results are discussed. Finally, the usefulness of the proposed device is proved in exemplary synthesis.

A LTCC microwave-microfluidic reactor

This paper describes a prototype of a LTCC microwave-microfluidic reactor, which was built to test a possibility of accelerating chemical reactions. The authors put their focus on conditions that must be met to assure reliable assessment of power that is delivered to the reactor, and which is used to stimulate a chemical reaction.

Design and Fabrication of Ceramic Microsystem Utilizing Glow Discharge for Analysis of Liquid Mixtures

Abstract We present the results of our work on design and fabrication of Low Temperature Co-fired Ceramics (LTCC) Electrolyte as a Cathode Discharge (ELCAD) chip. It consists of plasma chamber filled with working gas (for instance helium). The fluidic channel with sample is placed below the chamber. Discharge ignites between anode and electrolyte cathode through aperture between microfluidic channel and plasma chamber. To avoid filling the chamber with fluid, channel and waste outlet should have proper geometry. We have checked our design and fabricated prototypes in DuPont system. External electrodes have been screen-printed using solderable PdAg paste. Inner electrodes, responsible for plasma creation, were made of platinum. To avoid sagging of structures we have used Sacrificial Volume Materials (SVM) and conducted multistep lamination with modified parameters. Finally, we tested if our device works properly. Firstly, we created discharge using high voltage alternating current source in air and observe...

Impact of processing parameters on the LTCC channels geometry

Abstract A great advantage of Low Temperature Co-fired Ceramics (LTCC) yields the possibility of channel and air cavity fabrication. Such empty spaces have numerous applications, for example, in microfluidics, microwave techniques and integrated packaging. However, improper geometry of these structures can degrade the performance of the final device. The processing parameters recommended by the LTCC tape supplier are relevant for the production of multilayer circuits but not surface embedded channels and/or cavities. Thus, it is important to examine which factors of the fabrication process are the most significant. In our study, special attention has been paid to the geometric performance of the channel structure resulting from the applied processing parameters. Laser cutting parameters were checked to obtain the structures with great fidelity. The impact of an isostatic lamination on the quality of the final structure was analyzed. The influence of pressure and temperature of the lamination process on the channel geometry and tape shrinkage were examined. The performed experiments showed that some improvements in channel/cavity geometry may be achieved by optimizing the processing procedures. The microscopic observations combined with the Analysis of Variance (ANOVA) showed which combinations of the processing parameters are the best for achieving a channel/cavity structure with the desired geometry.

Improvement of the frequency bandwidth of LTCC meander antenna

The paper describes the study of possibility to improve the bandwidth of the LTCC (Low Temperature Cofired Ceramics) antennas. It is well-known that bandwidth broadening of microstrip antennas can be achieved by substrate structurizing. In our paper we describe the influence of an air cavity beneath a radiating patch or strip on the LTCC antenna performance. Results of computer simulations using HFSS™ software are shown. Then, manufacturing process is described. Results of measurement of network parameters and radiaton patterns of the antenna model are presented. Finally, a comparison between measured parameters and computer simulations is discussed.

A comparison of two practical methods for measurement of the dielectric constant of LTCC substrates

This paper describes a comparison of two methods that are used in practice to determine the dielectric constant of RF and microwave substrates, namely the method of two microstrip lines (the microstrip differential phase method) and SPDR (split post dielectric resonator) method. We compare accuracy of these two methods that is subject mainly to geometry measurements. Our case study, based on an LTCC (low temperature co-fired ceramic) material with high relative permittivity (εr=16), shows that the method of two microstrip lines has potential to give almost identical results to those from the SPDR method. Our approach, however, requires several samples to be measured, and the obtained results exhibit quite large standard deviation. In addition to this the approach is very sensitive to the quality of samples under test.

The LTCC device for miniature plasma generators characterization

Purpose The purpose of this paper is a presentation of a miniature vertical dielectric barrier discharge (DBD) plasma generators. The presented devices, with sub- and superstrate, were made using low temperature co-fired ceramics (LTCC). Such construction allowed to measure discharge spectra and device temperature easily. Design/methodology/approach The generators were made in the Du Pont 951 system with silver vertical metallizations and PdAg contacts. The devices had electrodes with different width and height. Also, the distance between them could be established. They were placed on substrate with buried temperature sensor and covered with a ceramic lid. The lid had opening to measure emitted light. Different configurations of vertical DBD were tested. Findings Geometry of vertical metallizations influences on spectra, as well as distance between them. Signal-to-noise ratio had a maximum for certain generators and can be measured by the intensity of highest peak. Research limitations/implications Height of vertical metallizations is limited by the difference in shrinkage of LTCC tape and via paste. Parameters of temperature sensors vary between measurements, according to rapid changes of temperature and presence of strong electric field. Practical implications The generators can be used for creating discharge for optical emission spectrometry. It is a convenient method to determine the amount of selected gas compounds. Originality/value This paper shows fabrication and performance of the novel vertical DBD generators with ceramic additions for convenient spectra measurement and monitoring temperature of the device during work.