Karol Malecha

A PDMS/LTCC bonding technique for microfluidic application

A novel bonding method of glass-covered low-temperature co-fired ceramics (LTCC) to transparent polydimethylsiloxane (PDMS) polymer is reported in this paper. The irreversible bonding between both materials was achieved by exposing their surfaces to an oxygen plasma. The influence of different plasma treatment process parameters (system power, time of surfaces activation) and glass/ceramics firing temperatures (Tmax = 700–875 °C, co-fired, post-fired) on the bonding process was investigated. Scanning electron microscopy (SEM) was used to study the glass surface quality after firing at various temperatures. Contact angle measurements, x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) and atomic force microscopy (AFM) were used to investigate properties of the PDMS and glass-covered LTCC surfaces before and after oxygen plasma treatment.

LTCC Enzymatic Microreactor

A novel three dimensional LTCC (Low Temperature Co-fired Ceramics) based microreactor with immobilized enzyme (urease) is presented in this paper. The microreactor consists of two chambers separated by a threshold. The shape of the chambers was optimized by the Finite Elements Method. The modeling has brought a better understanding of the microflow of chemically modified glass or polymeric beads through the microreactor. The modeling results are verified by the observation of the fluid movement inside the real structure via a top transparent polymer layer. Moreover, immobilization techniques of enzymes on polymeric beads are investigated. Finally, the properties of the LTCC microreactor are compared with the properties of a similar one made in silicon.

Three-dimensional structuration of zero-shrinkage LTCC ceramics for microfluidic applications.

In this paper, a simple and repeatable method for realization of microfluidic channels in zero-shrinkage LTCC Green TapeTM system (Heraeus® HL2000, Germany) is presented. This method is basing on two-step lamination process and use of sacrificial volume material (SVM). Three different fugitive materials are taken into account: high purity carbon paste, carbon tape (Thick Film Technologies, USA) and cetyl alcohol. The methods of analysis such as TGA (thermo-gravimetric analysis) and SEM (scanning electron microscope) are used to characterize this new fabrication process of microfluidic channels in zero-shrinkage LTCC ceramics.

Structuration of the low temperature co-fired ceramics (LTCC) using novel sacrificial graphite paste with PVA–propylene glycol–glycerol–water vehicle

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)–glycerol (G)–water mix, which is not aggressive to thin LTCC sheets. The presented sacrificial paste has been successfully applied for fabrication of thin (<50 μm) membranes and microchannels in low temperature co-fired ceramics (LTCC) substrate. The properties of the graphite-based paste have been examined using thermo-gravimetric analysis (TGA), differential thermo-gravimetric (DTG) and differential thermal analysis (DTA). The obtained membranes and microchannels have been investigated using scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and optical profile measurements gauge.

Argon plasma-assisted PDMS?LTCC bonding technique for microsystem applications

A method for transparent polymer (polydimethylosiloxane, PDMS) to glass-covered low-temperature co-fired ceramics (LTCC) using microwave argon plasma is reported in this paper. Changes in the composition of both materials before and after plasma treatment are investigated with x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy-attenuated total reflection and contact angle measurements. The results obtained for PDMS and glass-covered LTCC modified with argon plasma are compared with previously reported results received for oxygen plasma. Moreover, a comparison of adhesion between PDMS and glass-covered LTCC bonded together using Ar and O2 plasma is made using a material testing machine.

LTCC based microfluidic optical detector

A new fiber-based optical microfluidic detector was designed for low-volume sample measurement. Microdetector was fabricated by use of LTCC (low temperature co-fired ceramic) technology. The microdevice was made as separate module, which can be connected via tubing to any microanalytical system. The designed detector allowed to measure an optical absorbance (transmittance) in the analytical channel. Presented microfluidic detector can be also applied as a part of integrated muTAS (micro-total analysis system). The preliminary tests indicate linear absorbance detection in the range 9.5-28.5 mug/ml of cochineal red A and 10-20 mug/ml of sunset yellow in the test solutions

CFD simulations of LTCC based microsystems

This paper presents influence of fluidic inlet and outlet spacing on light transmission inside channel. To consider this issue three various LTCC (Low Temperature Co-fired Ceramics) based fluidic microsystems for light transmittance/absorbance measurements were designed and manufactured. The main distinction between these micro-devices was a way of fluidic inlet and outlet connection to the optical channel. Significant differences of output signal for each structure were noticed. To explain this phenomenon a CFD (Computational Fluid Dynamics) simulations were done.

Fabrication of cavities in low loss LTCC materials for microwave applications

A method of buried cavity fabrication in low loss DP951 and new DP9K7 LTCC (low-temperature co-fired ceramic) materials is described in this paper. Laser micromachining and method based on sacrificial volume material (SVM) are studied. Cavities are fabricated in LTCC materials using two different SVMs—cetyl alcohol and carbon tape. The influence of laser system parameters on cutting quality of the LTCC materials is studied. Moreover, thermal properties of the LTCCs and used SVMs are analyzed using combined thermo-gravimetric analysis, differential thermal analysis and differential thermo-gravimetry. Geometries of the LTCC test structures fabricated using different SVMs are analyzed using a scanning electron microscope and x-ray tomography. Energy dispersive spectroscopy and surface wettability measurements are used to analyze changes in LTCC materials atomic composition after co-firing with SVMs.

Three-dimensional fluidic microsystem fabricated in Low Temperature Cofired Ceramic Technology

A three-dimensional (3D) Low Temperature Cofired Ceramics (LTCC) fluidic microsystem integrated with an optical detection unit is presented in this article. The structure is applied to quantitative analysis of chemical compounds using colorimetric methods. The fabricated microfluidic system consists of a serpentine mixer, fluidic channels, heater, embedded temperature sensor and integrated optical fibers for detection of light transmission and/or fluorescence. A new inexpensive material for the embedded temperature sensor is described. The fluidic system is designed using computer CFD (Computational Fluid Dynamics) simulations. Fluid flow in the mixer is observed through a transparent polymer material bonded to the LTCC structure. The importance of positioning of optical fibers and their influence on the absorbance and fluorescence measurements is presented.

Optical coherence tomography : a potential tool for roughness assessment of free and embedded surfaces of laser-machined alumina ceramic

For an emerging market a mass and cost-effective production of non-silicon micro devices requires an in-process and accurate 3D monitoring to assure the quality. Optical coherence tomography (OCT) ...