Martin Adamek

Nanopatterned Working Electrode with Carbon Nanotubes Improving Electrochemical Sensors

This paper deals with problem of mercury drop electrodes replacement in classical polarography by more ecological solid electrodes. The screen-printed thick-film amperometric sensor was prepared for modification by nanostructures. Carbon nanotubes were grown on a working electrode. The process of nanotubes growing was improved to create homogenous and high density carbon nanotubes layer. The modified electrode is very perspective in heavy metal detection using electrochemical methods because of improvement detection properties. We were able to determine units of mumol/L of cadmium.

Nutritional Potential of Selected Insect Species Reared on the Island of Sumatra

Inhabitants of the Indonesian island of Sumatra are faced with the problem of insufficient food supplies and the consequent risk of undernourishment and health issues. Edible insects as a traditional and readily available food source could be part of the solution. The nutritional value of insects depends on many factors, e.g., species, developmental stage, sex, diet, and climatic conditions. However, edible insects bred in Sumatra for human consumption have never before been assessed with regard to their nutritional value. Our study involved analyses of crude protein, chitin, fat and selected fatty acid contents of giant mealworm larvae (Zophobas morio), larvae of the common mealworm (Tenebrio molitor) and nymphs of the field cricket (Gryllus assimilis). Crude protein content in the samples ranged from 46% to 56%. Highest (35%) and lowest (31%) amounts of fat were recorded in giant mealworm larvae and larvae of the common mealworm, respectively. Chitin amounts ranged from 6% to 13%. Based on these values, which are comparable to those known from other food insects reared in different regions of the world, the edible species bred in Sumatra could become food sources with a potential to help stave off hunger and undernourishment.

Development of new thick film sensor for heavy metals detection

The aim of this work is to find a perspective and ecological way for heavy metals detection. For this purpose we designed a new type of an amperometric sensor substrate, which joins a topology of ring disc electrode with an existing type of amperometric sensor produced by BVT Technologies Company. The sensor is fabricated using thick film technology. The intention was to prepare a base substrate for study of properties of materials used for working electrodes fabrication. In this work, the main emphasis was on sensor design and on materials of working and reference electrodes to ensure reproducible and reliable detection of heavy metals with sufficient limit of detection. In this work, various graphite materials for sensors working electrodes were prepared, screen-printed, measured and compared with a classical graphite electrode.

Effect of nitrogen atmosphere on the soldering process for different types of lead-free solders

An important part of the microelectronics manufacturing is the reflow process. Even though that the soldering have a long history, the process is still not completely described. Particular still discussed the introduction of the WEEE Directive 2003/108/EC standards and RoHS Directive 2002/95/EC got the soldering received into new areas. There is a space for new material compositions which do not contain lead. Furthermore, a new procedure process, adjusting of equipment and began to make greater use of nitrogen as protective gas. The aim is to compare the already proven commercial solder alloys on different carrier and evaluate more exactly the benefits of nitrogen atmosphere. The evaluation was performed for solder SAC, Sn100C and SnPb solder paste was used as reference. Type of substrates was printed circuit board FR-4 and ceramic substrate. Soldering conducted in atmosphere with different residual oxygen. Results of this paper may serve to increase the quality of soldering classical package as well as BGA and CSP package.

Reference electrodes for thick-film sensors

Paper deals with a problematic of thick-film electrochemical sensors for trace analysis of species or elements in aqueous solutions. A problem of replacement of classical Ag/AgCl reference electrodes by planar thick-film electrodes is discussed here. In this paper there were compared several thick-film reference electrodes with classical ones using the same electrochemical arrangement. Special commercial thick-film pastes and electrochemically fabricated Ag/AgCl layers were used for reference electrodes of thick-film electrochemical sensors and characterized in standard electrochemical solution of potassium ferro-ferricyanide. First results show big difference between tested materials, mainly in shifts of half weave potentials. Moreover with use of screen-printed reference electrodes, there was shown a high output current dependence on the change of electrodes distances.

The Topology Optimisation of Thick-Film Electrochemical Sensor

An electrode topology design is one of the important parts of thick-film electrochemical sensors design. The rules for optimization of electrode systems in classical electrochemistry exist, but the thick-film electrodes topology design is limited (substrate dimensions, resolution, paste parameters, etc.). Therefore rules for classical electrode systems cannot be used fully in this case. The aim of this work is cognition and description of some knowledge about the topology optimisation of thick-film electrochemical sensors.

Impact of solder paste drying on the solderability

This paper deals with the influence of the dried no-clean SAC305 solder paste on the spreading factor. Drying was defined by time between stencil printing and reflow soldering. Main investigated parameter was spreading, which is percentage difference between diameter of circle of solder paste after printing and diameter of circle after soldering.

Committing of electronic modules by ball pins and their reliability

The article states first results of reliability measurement of committing of electronic modules with printed circuit board by lead-free solder balls (SAC 305). In order to obtain experimental data, the test boards are periodically exposed to thermal load from −20°C to +100°C with 20 minutes dwell time on the maximum and minimum temperatures. Test samples are produced on alumina ceramics and/or four-layer LTCC ceramics. Test samples are soldered on to boards with various surface finishes: galvanic gold and HAL. The goal of the experiment is to determine the lifetime of ball solder joints in relation to varying thermal conductivity coefficient of base materials.

Testing of graphite paste properties for thick film sensors

The miniature electrochemical sensors can be produced by thick film technology. The optimal properties of thick film electrode materials are main problems of sensors design. The optimization of graphite paste for TFT chemical sensor properties is discussed. The commercial TFT graphite pastes, which are used for common application, are cheap and easily producible, but they are not efficient for electrochemical measurement. These pastes have insufficient sensitivity and they have other bad properties. Graphite pastes, which were designed for special chemical analysis, are technically known, but these pastes are not workable by screen-printing. The goal of this work is first step in rheologic properties addition to graphite electrochemical pastes. This ensures the pastes printability that will enable the reproducible mass production. The graphite powder mixed with paraffin is the basic component of common chemical graphite pastes. There were examined different properties of these pastes in dependence on graphite powder and binding material content in this work. The measurement was made in standard electrochemical couple of potassium ferrocyanide-ferricyanide.

The properties comparison of solder joints on ceramic and FR-4 substrates

Reliability of electro-technical products is still a highly actual and discussed topic. Every electro-technical product consists not only of the components, functional blocks and systems, but also substrate as printed circuit board (PCB) or ceramic substrates, which are interconnected by solder joints. This article is focuses on a comparison of some properties of solder joints on ceramic and PCB substrates. Standard aluminum oxide ceramics (corundum) with thickness t = 0.65 mm was used as the ceramic substrate. Standard FR-4 board with a thickness t = 1.5 mm was used as the PCB substrate. This paper compares the main strength of solder joint at various concentrations of O2, type solders (SnPb, SnAgCu, …), the size of components (0402, 0603, 2512, …) and material surfaces. Shear test equipment DAGE was used to compare the mechanical strength.