Micropatterning is miniaturization of periodic structures on the surface. The application of micropatterning is rapidly increasing in engineering[sup]1,2, biomaterials engineering[sup]3, cellular biology[sup]4,5, biomedicine[sup]6, opto-electronics[sup]7 and other fields. Most traditional method for micropatterning and microstructuring is photolithography which is basis for today's computer microchip production. Similar is soft tithography which is a class of techniques using elastomeric materials, which is chipper for mass production and especially convenient for biomedical applications. In order to find cheaper faster and more accurate methods a number of techniques have been investigated like, direct-write laser (X-ray, ion beam, e-beam) lithography, nanoimprint lithography, drying/evaporative lithography, self-assembly methods, aerosols micropatterning and others. One of alternative methods is Laser Direct Imaging (LDI), a technique where a laser beam is used to image a pattern directly on photoresist-coated surface and thus avoids photomask fabrication. The most obvious difference from the traditional photolithography is the benefit of time and cost savings associated with the creation, use handling and storage of photo tools. Further, this method avoids problems related to mask related defects. The novel LPKF developed ProtoLaser LDI system has a superior 1 [mu]m laser spot size which allows for very small structure resolution. Implementation of acusto-optic deflector allows for extremely fast and accurate writing with positioning accuracy beloww 1 nm. We present several patterns on micron and sub-micron scale for antibiofouling and microfluidics applications created by this novel LPKF LDI system.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 966058The aim of the doctoral thesis was to examine the influence of material properties of stainless steel AISI 316 L and Ag and TiOx thin films deposited on the AISI 316L steel substrate, on the adhesion of model bacteria Escherichia coli (E. coli). Six different surfaces finish on AISI 316L stainless steel was prepared and compared to the samples with deposited Ag and TiOx thin films. The effect of surface roughness, topography, surface chemistry and surface energy on bacterial adhesion was studied using scanning electron microscope (SEM), atomic force microscope (AFM) as well as Auger Electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS). Surface characterization revealed that stainless steel (SS) surface finishes did not differ in surface chemistry and hydrophobicity only topography and roughness varied considerably. SS samples of different surface finishes with deposited Ag and TiOx thin films are more hydrophilic compared to basic SS and exhibited larger difference in hydrophobicity without any observable difference in surface chemistry. Addition of Ag and TiOx thin films did not alter the roughness and topography of basic SS samples however we observed additional nanotopography due to the sputtering process. E. coli adhere to all, basic SS and samples with deposited Ag and TiOx thin films and the adhesion on all surfaces/surface finishes was correlated with surface roughness. On basic SS samples minimal adhesion was observed on A800 surface finish (Ra 0.08 µm), whereas on samples with deposited Ag and TiOx thin films, minimal adhesion was observed on A1200 surface finish (Ra 0.04–0.05 µm). Adhesion to all basic and samples with Ag and TiOx thin films rougher (A100, AIZV, A320) and smoother (APOL) surfaces was higher. Surface topography on the other hand influenced the pattern of adhesion. E. coli cells tend to concentrate in and along surface morphological features (pits, crevices, scratches grooves and ridges) which are of similar size as the cells. The adhesion of bacteria was significant lower on the Ag deposited SS compared to basic and TiOx thin films SS, thus demonstrating the influence of surface chemistry on the adhesion.
F.02 Acquisition of new scientific knowledge
COBISS.SI-ID: 1089706Automation of the recognition process of Auger spectra has turned out to be quite a tedious task. Attempts by various researchers have been made. Two elements of the measured spectra which greatly interfere with the automatic recognition process are background and noise. Both interfere in quantitative evaluation of characteristic peaks of elements, whereas some of the spikes coming out as a result of noise, in the automatic recognition process will be falsely accounted for as peaks. Thus for further data preparation, finding proper methods for background removal and noise reduction is a must. Even though the idea is straight forward, this is not an easy task, because whenever the data is manipulated through background removal and noise reduction methods, the risk of altering the original data is always present and unfortunately unavoidable. Our team is studying methods to accomplish the data preparation for automatic recognition which will cause minimal or at least controllable loss of the original data.
F.02 Acquisition of new scientific knowledge
COBISS.SI-ID: 278279936Reliable, autonomous, internally self-powered microfluidic pumps are in critical demand for rapid point-of-care (POC) devices, integrated molecular-diagnostic platforms, and drug delivery systems. Here we report on a Self-powered Imbibing Microfluidic Pump by Liquid Encapsulation (SIMPLE), which is disposable, autonomous, easy to use and fabricate, robust, and cost efficient, as a solution for self-powered microfluidic POC devices. The imbibition pump introduces the working liquid which is sucked into a porous material (paper) upon activation. The suction of the working liquid creates a reduced pressure in the analytical channel and induces the sequential sample flow into the microfluidic circuits. It requires no external power or control and can be simply activated by a fingertip press. The flow rate can be programmed by defining the shape of utilized porous material: by using three different paper shapes with circular section angles 20°, 40° and 60°, three different volume flow rates of 0.07 micro L s-1, 0.12 micro L s-1 and 0.17 micro L s-1 are demonstrated at 200 micro m x 600 micro m channel cross-section. We established the SIMPLE pumping of 17 micro L of sample; however, the sample volume can be increased to several hundreds of micro L.
F.08 Development and manufacture of a prototype
COBISS.SI-ID: 1068714