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Bacterial lipopolysaccharides (endotoxins) show strong biological effects at very low concentrations in human beings and many animals when entering the blood stream. These include affecting structure and function of organs and cells, changing metabolic functions, raising body temperature, triggering the coagulation cascade, modifying hemodynamics and causing septic shock. Because of this toxicity, the removal of even minute amounts is essential for safe parenteral administration of drugs and also for septic shock patients' care. The absence of a general method for endotoxin removal from liquid interfaces urgently requires finding new methods and materials to overcome this gap. Nanostructured carbonized plant parts is a promising material that showed good adsorption properties due to its vast pore network and high surface area. The aim of this study was comparative measurement of endotoxin- and blood proteins-related adsorption rate and adsorption capacity for different carboneous materials produced at different temperatures and under different surface modifications. As a main surface modificator, positively cbarged polymer, polyethileneimine (PEl) was used. Activated carbon materials showed good adsorption properties for LPS and some proteins used in the experiments. During the batch experiments, several techniques (dust removal, autoclaving) were used and optimized for improving the material's adsorption behavior. Also, with the results obtained it was possible to differentiate the materials according to their adsorption capacity and kinetic characteristics. Modification of the surface apparently has not affected hemoglobin binding to the adsorbent's surface. Obtained adsorption isotherms can be used as a powerful tool for designing of future column-based setups for blood purification from LPS, which is especially important for septic shock treatment.
On the model of musculocutaneous wound in rats, the effect of applicative sorption by carbonized rise shell (CRS) on the healing of festering wound was studied. It has been shown, that cytological changes end with rapid scar formation. The use of CRS at the period of severe purulent wound contributes to its favorable course, prevents the development of complications of the animals from sepsis.
Objective
To investigate whether functional brain networks of epilepsy patients treated with antiepileptic medication differ from networks of healthy controls even during the seizure-free interval.
Methods
We applied different rules to construct binary and weighted networks from EEG and MEG data recorded under a resting-state eyes-open and eyes-closed condition from 21 epilepsy patients and 23 healthy controls. The average shortest path length and the clustering coefficient served as global statistical network characteristics.
Results
Independent on the behavioral condition, epileptic brains exhibited a more regular functional network structure. Similarly, the eyes-closed condition was characterized by a more regular functional network structure in both groups. The amount of network reorganization due to behavioral state changes was similar in both groups. Consistent findings could be achieved for networks derived from EEG but hardly from MEG recordings, and network construction rules had a rather strong impact on our findings.
Conclusions
Despite the locality of the investigated processes epileptic brain networks differ in their global characteristics from non-epileptic brain networks. Further methodological developments are necessary to improve the characterization of disturbed and normal functional networks.
Significance
An increased regularity and a diminished modulation capability appear characteristic of epileptic brain networks.
Epilepsy
(2010)
We consider recent reports on small-world topologies of interaction networks derived from the dynamics of spatially extended systems that are investigated in diverse scientific fields such as neurosciences, geophysics, or meteorology. With numerical simulations that mimic typical experimental situations, we have identified an important constraint when characterizing such networks: indications of a small-world topology can be expected solely due to the spatial sampling of the system along with the commonly used time series analysis based approaches to network characterization.
Recently, we introduced and mathematically analysed a new method for grid deformation (Grajewski et al., 2009) [15] we call basic deformation method (BDM) here. It generalises the method proposed by Liao et al. (Bochev et al., 1996; Cai et al., 2004; Liao and Anderson, 1992) [4], [6], [20]. In this article, we employ the BDM as core of a new multilevel deformation method (MDM) which leads to vast improvements regarding robustness, accuracy and speed. We achieve this by splitting up the deformation process in a sequence of easier subproblems and by exploiting grid hierarchy. Being of optimal asymptotic complexity, we experience speed-ups up to a factor of 15 in our test cases compared to the BDM. This gives our MDM the potential for tackling large grids and time-dependent problems, where possibly the grid must be dynamically deformed once per time step according to the user's needs. Moreover, we elaborate on implementational aspects, in particular efficient grid searching, which is a key ingredient of the BDM.
Self metathesis of oleochemicals offers a variety of bifunctional compounds, that can be used as monomer for polymer production. Many precursors are in huge scales available, like oleic acid ester (biodiesel), oleyl alcohol (tensides), oleyl amines (tensides, lubricants). We show several ways to produce and separate and purify C18-α,ω-bifunctional compounds, using Grubbs 2nd Generation catalysts, starting from technical grade educts.
Metathese von Ölsäure und Derivaten ist ein interessanter Weg für die Synthese bifunktioneller Verbindungen aus nachwachsenden Rohstoffen. Verwendet wurden Ru-Katalysatoren der zweiten Generation, welche eine hohe Toleranz gegenüber funktionellen Gruppen und Verunreinigungen aufweisen. Trotz des Einsatzes technischer Edukte waren Umsetzungen mit niedrigen Katalysatormengen (0.001 – 0.01 mol-%) möglich, mit Ausbeuten entsprechend der Literatur. Kreuzmetathesen ermöglichten variable Kettenlängen und Funktionalitäten der Monomere, die Produktgewinnung ist jedoch aufwändig. Selbstmetathese lieferte C18-bifunktionelle Verbindungen, welche einfach durch Destillation oder Kristallisation isoliert werden können. Neben der katalystischen Umsetzung wurde auch die Produktgewinnung untersucht und für ausgewählte Produkte auch im größeren Maßstab durchgeführt.
Autonomous robotic systems for penetrating thick ice shells with simultaneous collecting of scientific data are very promising devices in both terrestrial (glacier, climate research) and extra-terrestrial applications. Technical challenges in development of such systems are numerous and include 3D-navigation, an appropriate energy source, motion control, etc. Not less important is the problem of forward contamination of the pristine glacial environments with microorganisms and biomolecules from the surface of the probe. This study was devoted to establishing a laboratory model for microbial contamination of a newly constructed ice-melting probe called IceMole and to analyse the viability and amount of the contaminating microorganisms as a function of distance. The used bacterial strains were Bacillus subtilis (ATCC 6051) and Escherichia coli (ATCC 11775). The main objective was development of an efficient and reliable in-situ decontamination method of the melting probe. Therefore, several chemical substances were tested in respect of their efficacy to eliminate bacteria on the surface of the melting probe at low temperature (0 - 5 °C) and at continuous dilution by melted water. Our study has shown that at least 99.9% decontamination of the IceMole can be successfully achieved by the injection of 30% (v/v) hydrogen peroxide and 3% (v/v) sodium hypochlorite into the drilling site. We were able to reproduce this result in both time-dependent and depth-dependent experiments. The sufficient amount of 30% (v/v) H₂O₂ or 3% (v/v) NaClO has been found to be approximately 18 L per cm² of the probe’s surface.
The chemical imaging sensor is a semiconductor-based chemical sensor that can visualize the two-dimensional distribution of specific ions or molecules in the solution. In this study, we developed a miniaturized chemical imaging sensor system with an OLED display panel as a light source that scans the sensor plate. In the proposed configuration, the display panel is placed directly below the sensor plate and illuminates the back surface. The measured area defined by illumination can be arbitrarily customized to fit the size and the shape of the sample to be measured. The waveform of the generated photocurrent, the currentvoltage characteristics and the pH sensitivity were investigated and pH imaging with this miniaturized system was demonstrated.
Es wurde ein automatisiertes, computerunterstütztes Testsystem für die Funktionsprüfung und Charakterisierung von (bio-)chemischen Sensoren auf Waferebene entwickelt und in einen konventionellen Spitzenmessplatz integriert. Das System ermöglicht die Charakterisierung und Identifizierung „funktionstauglicher“ Sensoren bereits auf Waferebene zwischen den einzelnen Herstellungsschritten, wodurch weitere, bisher übliche Verarbeitungsschritte wie das Fixieren, Bonden und Verkapseln für die defekten oder nicht funktionstauglichen Sensorstrukturen entfällt. Außerdem bietet eine speziell entworfene miniaturisierte Durchflussmesszelle die Möglichkeit, bereits auf Waferlevel die Sensitivität, Drift, Hysterese und Ansprechzeit der (bio-)chemischen Sensoren zu charakterisieren. Das System wurde exemplarisch mit kapazitiven, pH-sensitiven EIS- (Elektrolyt-Isolator-Silizium) Strukturen und ISFET- (ionensensitiver Feldeffekttransistor) Strukturen mit verschiedenen Geometrien und Gate-Layouts getestet.
Realization of a calorimetric gas sensor on polyimide foil for applications in aseptic food industry
(2010)
A calorimetric gas sensor is presented for the monitoring of gas-phase H2O2 at elevated temperature during sterilization processes in aseptic food industry. The sensor consists of two temperature-sensitive thin-film resistances built up on a polyimide foil with a thickness of 25 μm, which are passivated with a layer of SU-8 photo resist and catalytically activated with manganese(IV) oxide. Instead of an active heating structure, the calorimetric sensor utilizes the elevated temperature of an evaporated H2O2 aerosol. In an experimental set-up, the sensor has shown a sensitivity of 4.78 °C/(%v/v) in a H2O2 concentration range of 0 to 10% v/v at an evaporation temperature of 240 ∘C. Furthermore, the sensor possesses the same, unchanged sensor signal even at varied evaporation temperatures of the gas stream. The sensor characterization demonstrates the suitability of the calorimetric gas sensor for monitoring the efficiency of sterilization processes.
In this contribution, we focus on the detection of toxic gases with living eukaryotic cells. A cell-based gas sensor system, able to measure the effects of direct exposure of gases to cells in real-time, was set up. Impedance data as well as oxygen consumption of Chinese hamster lung fibroblast cells (V79) were analysed upon exposure to carbon monoxide (CO). The CO (diluted in wet synthetic air) affects the cell respiration as indicated by an attenuated respiration signal after the CO exposure as well as an instant increase of the capacitive part of the impedance signal during the gas exposure.
In aseptischen Abfüllsystemen wird Wasserstoffperoxid in der Gasphase aufgrund der stark oxidativen Wirkung zur Packstoffentkeimung eingesetzt. Dabei wird die Effizienz der Entkeimung im Wesentlichen von der vorliegenden H2O2-Konzentration im Packstoff bestimmt. Zur Inline-Überwachung der H2O2-Konzentration wurde ein kalorimetrischer Gassensor auf Basis einer flexiblen Polyimidfolie aus temperatursensitiven Dünnschicht-Widerständen und Mangan(IV)-oxid als katalytische Transducerschicht realisiert. Der Sensor weist ein lineares Ansprechverhalten mit einer Sensitivität von 7,15 °C/Vol.-% in einem H2O2-Konzentrationsbereich von 0 bis 8 Vol.-% auf. Weiterhin wurde zur Auslesung des Sensorsignals eine RFID-Elektronik, bestehend aus einem Sensor-Tag und einer Sende-/Empfangseinheit ausgelegt, sowie eine Abfolge des Messzyklus aufgestellt. Im weiteren Verlauf soll der kalorimetrische Gassensor mit der RFID-Elektronik gekoppelt und in eine Testverpackung zur Inline-Überwachung der H2O2-Konzentration in aseptischen Abfüllsystemen implementiert werden.
Chalcogenide glass materials as membranes for potentiometric sensors for chemical analysis in solutions have been studied since more than 20 years. In this work, an electrolyte–insulator–semiconductor structure was combined with chalcogenide glass membranes prepared by means of the pulsed laser deposition technique. Depending on the membrane composition a selectivity to different ions (Cd2+ and Pb2+) is achieved. The different sensor membranes have been physically characterised using microscopy, ellipsometry, profilometry, atomic force microscopy (AFM), scanning electron microscopy (SEM) and Rutherford backscattering spectrometry (RBS). The electrochemical behaviour has been investigated via capacitance/voltage (C/V) and constant capacitance (ConCap) measurements and results in a Cd2+ sensitivity of 23.1 ± 0.6 mV per decade in a linear range from 7 × 10−6 to 10−2 mol/l and 24.4 ± 0.5 mV per decade in a linear range from 5 × 10−6 to 10−2 mol/l for Pb2+, respectively.
Ein lichtadressierbarer potentiometrischer Sensor (LAPS) kann die Konzentration eines oder mehrerer Analyten ortsaufgelöst auf der Sensoroberfläche nachweisen. Dazu wird mit einer modulierten Lichtquelle die Halbleiterstruktur des zu untersuchenden Bereiches angeregt und ein entsprechender Photostrom ausgelesen. Durch gleichzeitige Anregung mehrere Bereiche durch Lichtquellen mit unterschiedlichen Modulationsfrequenzen können diese auch zeitgleich ausgelesen werden. Mit der neuen, hier vorgestellten Ansteuerungselektronik integriert in einem "Field Programmable Gate Array" (FPGA) ist es möglich, mehrere Leuchtquellen gleichzeitig mit unterschiedlichen, während der Laufzeit festlegbaren Frequenzen, Phasen und Lichtintensitäten zu betreiben. Somit kann das Frequenzverhalten des Sensors untersucht und die Konzentration des Analyten über das Oberflächenpotential mit Hilfe von Strom/Spannungs-Kurven und Phase/Spannungs-Kurven bestimmt werden.
In diesem Beitrag werden Ergebnisse der Entwicklung eines modularen festkörperbasierten Sensorsystems für die Überwachung von Zellkulturfermentationen präsentiert. Zur Messung der Elektrolytleitfähigkeit wurde das Layout von Interdigitalelektroden angepasst, um in vergleichsweise gut leitenden Elektrolyten zu messen. Durch Quervernetzung von Glucose-Oxidase mit Glutaraldehyd und Immobilisierung auf einer Platinelektrode wurde ein amperometrischer Glucosesensor mit einem linearen Messbereich von bis zu 2 mM und einer Sensitivität von 168 nA/mM realisiert.
The importance of validating and reproducing the outcome of computational processes is fundamental to many application domains. Assuring the provenance of workflows will likely become even more important with respect to the incorporation of human tasks to standard workflows by emerging standards such as WS-HumanTask. This paper addresses this trend by an actor-based workflow approach that actively support provenance. It proposes a framework to track and store provenance information automatically that applies for various workflow management systems. In particular, the introduced provenance framework supports the documentation of workflows in a legally binding way. The authors therefore use the concept of layered XML documents, i.e. history-tracing XML. Furthermore, the proposed provenance framework enables the executors (actors) of a particular workflow task to attest their operations and the associated results by integrating digital XML signatures.
Chemical imaging systems allow the visualisation of the distribution of chemical species on the sensor surface. This work represents a new flexible approach of read out in a light-addressable potentiometric sensor (LAPS) with the help of a digital light processing (DLP) set-up. The DLP, known well for video projectors, consists of a mirror-array MEMS device which allows fast and flexible generation of light patterns. With the help of these light patterns the sensor surface of the LAPS device can be read out sequentially in a raster like scheme (scanning LAPS). The DLP approach has several advantages compared to conventional scanning LAPS set-ups, e.g., the spot size, the shape and the intensity of the light pointer can be changed easily and no mechanical movement is necessary, which reduces the size of the set-up and increases the stability and speed of measurement.
A new approach for a label-free electrical detection of DNA hybridization and denaturation using an array of individually addressable field-effect nanoplate SOI (silicon-on-insulator) capacitors functionalized with gold nanoparticles is presented. By using a constant-capacitance measuring setup in a differential mode, signal changes of ∼110 mV and ∼70 mV have been registered after the DNA hybridization and denaturation events, respectively.
Currently, most workflow management systems in Grid environments provide push-oriented job distribution strategies, where jobs are explicitly delegated to resources. In those scenarios the dedicated resources execute submitted jobs according to the request of a workflow engine or Grid wide scheduler. This approach has various limitations, particularly if human interactions should be integrated in workflow execution. To support human interactions with the benefit of enabling inter organizational computation and community approaches, this poster paper proposes the idea of a pull-based task distribution strategy. Here, heterogeneous resources, including human interaction, should actively select tasks for execution from a central repository. This leads to special demands regarding security issues like access control. In the established push-based job execution the resources are responsible for granting access to workflows and job initiators. In general this is done by access control lists, where users are explicitly mapped to local accounts according to their policies. In the pull-based approach the resources actively apply for job executions by sending requests to a central task repository. This means that every resource has to be able to authenticate against the repository to be authorized for task execution. In other words the authorization is relocated from the resources to the repository. The poster paper introduces current work regarding to the mentioned security aspects in the pull-based approach within the scope of the project “HiX4AGWS”.
The development of new interfaces for (bio-)chemical sensors requires comprehensive analyses and testing. The light-addressable potentiometric sensor (LAPS) can be used as a platform to investigate the sensitivity of a newly developed interface towards (bio-)chemical agents. LAPS measurements are spatially resolved by utilisation of focused light beams to define individual measurement spots. In this work, a new digitally modulated LAPS set-up based on an FPGA design will be introduced to increase the number of measurement spots, to shorten the measurement time and to improve the measurement accuracy.
A novel scheme for precise diagnostics and effective stabilization of currents in a fuel cell stack
(2010)
A novel scheme for detecting inhomogeneous internal currents in a fuel cell stack is presented. In this paper the scheme is investigated for the case that the flow field plates consist of graphite. Then plates of high conductivity, e.g. aluminium between the flow field plates together with small slits in these plates have three effects: (a) Whenever a local inhomogeneity of the electric current occurs at a particular cell in the stack, this will induce a surface current close to that cell perpendicular to the averaged current. This current can be detected. (b) The plates of high conductivity completely prevent the inhomogeneities from spreading to neighbouring cells. (c) Even at the particular cell the inhomogeneity is suppressed as far as possible. Thus this scheme leads to much better diagnostic possibilities and at the same time reduces electric instabilities to an extent, where they probably become harmless. This scheme will first be explained for a simple model to clarify the idea. However, very precise three dimensional computations using realistic parameters are presented, corroborating the results of the simple model.
A novel tomographic scheme for analysing the state of any single membrane electrode assembly (MEA) in a stack is suggested. Plates of very high conductivity placed between every fuel cell and slitted in an appropriate manner cause surface currents at well-defined locations of the stack. We show that knowing these surface currents, information about anomalies of the currents in a MEA can be obtained using the methods of tomography. The results are mathematically not unique. However, when assuming plausible defect structures, one can exclude improbable deficiencies by applying a special form of simulated annealing. We present numerical calculations of typical examples demonstrating that the essential defects of the MEA in any single cell of the stack can be detected and their extent can be determined.
Biomechanics studies biological soft tissue materials (growth, remodeling) in vivo. For this objective, the detailed information of material properties must be well defined to construct reliable constitutive models. In the paper, the bulge test is carried out with elastomers in order to develop a test method. Then, application of the test for soft tissue materials is straightforward due to the similarities between elastomers with soft tissue materials as proved in Holzapfel 2005, Ogden 2009. It means, after the preliminary experiments and parameter identification with rubber materials has been setup, experiments on soft tissue materials can be similarly carried out. Elastomers have a complex behavior which strongly depends on the largest previous load cycle. For simplicity we consider only the first loading.
Capacitive field-effect electrolyte-diamond-insulator-semiconductor (EDIS) structures with O-terminated nanocrystalline diamond (NCD) as sensitive gate material have been realized and investigated for the detection of pH, penicillin concentration, and layer-by-layer adsorption of polyelectrolytes. The surface oxidizing procedure of NCD thin films as well as the seeding and NCD growth process on a Si-SiO2 substrate have been improved to provide high pH-sensitive, non-porous thin films without damage of the underlying SiO2 layer and with a high coverage of O-terminated sites. The NCD surface topography, roughness, and coverage of the surface groups have been characterized by SEM, AFM and XPS methods. The EDIS sensors with O-terminated NCD film treated in oxidizing boiling mixture for 45 min show a pH sensitivity of about 50 mV/pH. The pH-sensitive properties of the NCD have been used to develop an EDIS-based penicillin biosensor with high sensitivity (65-70 mV/decade in the concentration range of 0.25-2.5 mM penicillin G) and low detection limit (5 μM). The results of label-free electrical detection of layer-by-layer adsorption of charged polyelectrolytes are presented, too.
Shakedown analysis of two dimensional structures by an edge-based smoothed finite element method
(2010)
Urinary stone formation has been evolved to a widespread disease during the last years. The reason for the formation of urinary stones are little crystals, mostly composed of calcium oxalate, which are formed in human kidneys. The early diagnosis of the risk for urinary stone formation of patients can be determined by the “Bonn-Risk-Index” method based on the potentiometric detection of the Ca2+-ion concentration and an optical determination of the triggered crystallisation of calcium oxalate in unprocessed urine. In this work, miniaturised capacitive field-effect EMIS (electrolyte-membrane-insulator-semiconductor) sensors have been developed for the determination of the Ca2+-ion concentration in human native urine. The Ca2+-sensitive EMIS sensors have been systematically characterised by impedance spectroscopy, capacitance–voltage and constant–capacitance method in terms of sensitivity, signal stability and response time in both CaCl2 solutions and in native urine. The obtained results demonstrate the suitability of EMIS sensors for the measurement of the Ca2+-ion concentration in native urine of patients.
A handheld sensor system for the online measurement of hydrogen peroxide (H2O2) in aseptic sterilisation processes has been developed. It is based on a calorimetric-type gas sensor that consists of a differential set-up of two temperature sensors, of which one is catalytically activated and the second one is passivated and used as reference. The sensor principle relies in detecting a rise in temperature on the active sensor due to the exothermic reaction of H2O2 on the catalytic surface. To characterise the sensor system towards H2O2 sensitivity and other influencing factors, measurements have been carried out both at an experimental set-up and a manufacturer's sterilisation machine. Physical sensor characterisation was done by means of the optical microscopy.
The chemical imaging sensor is a semiconductor-based chemical sensor that can visualize the spatial distribution of chemical species. For the practical application of this sensor, artifacts in the chemical images due to defects of the semiconductor substrate and contamination of the sensing surface etc. have been a major problem. An image correction method was developed to eliminate the influence of nonuniformity of individual sensor plate.
A novel strategy for enhanced field-effect biosensing using capacitive electrolyte–insulator–semiconductor (EIS) structures functionalised with pH-responsive weak polyelectrolyte/enzyme or dendrimer/enzyme multilayers is presented. The feasibility of the proposed approach is exemplarily demonstrated by realising a penicillin biosensor based on a capacitive p-Si–SiO2 EIS structure functionalised with a poly(allylamine hydrochloride) (PAH)/penicillinase and a poly(amidoamine) dendrimer/penicillinase multilayer. The developed sensors response to changes in both the local pH value near the gate surface and the charge of macromolecules induced via enzymatic reaction, resulting in a higher sensitivity. For comparison, an EIS penicillin biosensor with adsorptively immobilised penicillinase has been also studied. The highest penicillin sensitivity of 100 mV/dec has been observed for the EIS sensor functionalised with the PAH/penicillinase multilayer. The lower and upper detection limit was around 20 µM and 10 mM, respectively. In addition, an incorporation of enzymes in a multilayer prepared by layer-by-layer technique provides a larger amount of immobilised enzymes per sensor area, reduces enzyme leaching effects and thus, enhances the biosensor lifetime (the loss of penicillin sensitivity after 2 months was 10–12%).
Gas sensor investigation based on a catalytically activated thin-film thermopile for H2O2 detection
(2010)
In aseptic filling systems, hydrogen peroxide vapour is commonly used for the reduction of microbial contaminations in carton packages. In this process, the germicidal efficiency of the vapour depends especially on the H₂O₂ concentration. To monitor the H₂O₂ concentration, a calorimetric H₂O₂ gas sensor based on a catalytically activated thin-film thermopile is investigated. Two different sensor layouts, namely a circular and a linear form, as well as two various material pairs such as tungsten/nickel and gold/nickel, have been examined for the realization of a thin-film thermopile. Additionally, manganese oxide and palladium particles have been compared as responsive catalysts towards H₂O₂. The thin-film sensors have been investigated at various H₂O₂ concentrations, gas temperatures and flow rates.
pH-sensitive properties of barium strontium titanate (BST) high-k thin films as alternative gate material for field-effect capacitive (bio-)chemical sensors based on an electrolyte-insulator-semiconductor system have been investigated. The BST films of different compositions (Ba0.31Sr0.69TiO3, Ba0.25Sr0.75TiO3 and Mg-doped Ba0.8Sr0.2Mg0.1Ti0.9O3) were deposited by pulsed laser deposition technique from targets fabricated by self-propagating high-temperature synthesis. The realised sensors have been electrochemically characterised by means of impedance-spectroscopy, capacitance–voltage and constant-capacitance method. The sensors possess a Nernstian-like pH sensitivity in the concentration range between pH 3 and 11 with a response time of 5–10 s. An equivalent circuit model for the BST-based capacitive field-effect sensor is discussed.
Simultaneous detection of cyanide and heavy metals for environmental analysis by means of µISEs
(2010)
In environmental analysis, cyanide and heavy metals play an important role, because these substances are highly toxic for biological systems. They can lead to chronic and acute diseases. Due to the chemical properties of cyanide it is frequently used for industrial processes such as extraction of silver and gold. Heavy metals can be found as trace elements in nature and are often applied in industries e.g., galvanization processes. Up to now, cyanide and heavy metals can be detected by several sensors separately and their detection is often limited to laboratory investigations. In this publication, with regard to an in situ analysis, a new miniaturized silicon-based sensor system for the simultaneous detection of cyanide and heavy metals in aqueous solutions is presented that is based on chalcogenide glass-based micro ion-selective electrodes (µISEs). The µISEs are incorporated into a specially designed measuring system for the simultaneous detection of heavy metals and cyanide in solutions and validated by simultaneous measurements of Cu2+- and CN−-ions, Cd2+- and CN−- ions and Pb2+- and CN−-ions. The particular sensor system has shown good sensor properties in the µ-molar ion-concentration range. For simultaneous measurements in complex heavy metal and cyanide solutions an intelligent software using fuzzy logic is discussed.
The control of molecular architecture provided by the layer-by-layer (LbL) technique has led to enhanced biosensors, in which advantageous features of distinct materials can be combined. Full optimization of biosensing performance, however, is only reached if the film morphology is suitable for the principle of detection of a specific biosensor. In this paper, we report a detailed morphology analysis of LbL films made with alternating layers of single-walled carbon nanotubes (SWNTs) and polyamidoamine (PAMAM) dendrimers, which were then covered with a layer of penicillinase (PEN). An optimized performance to detect penicillin G was obtained with 6-bilayer SWNT/PAMAM LbL films deposited on p-Si-SiO2-Ta2O5 chips, used in biosensors based on a capacitive electrolyte-insulator-semiconductor (EIS) and a light-addressable potentiometric sensor (LAPS) structure, respectively. Field-emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) images indicated that the LbL films were porous, with a large surface area due to interconnection of SWNT into PAMAM layers. This morphology was instrumental for the adsorption of a larger quantity of PEN, with the resulting LbL film being highly stable. The experiments to detect penicillin were performed with constant-capacitance (ConCap) and constant-current (CC) measurements for EIS and LAPS sensors, respectively, which revealed an enhanced detection signal and sensitivity of ca. 100 mV/decade for the field-effect sensors modified with the PAMAM/SWNT LbL film. It is concluded that controlling film morphology is essential for an enhanced performance of biosensors, not only in terms of sensitivity but also stability and response time.