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Current codes of practice, mainly devoted to new structures, do not include information and approaches relevant to old material and products. At the same time, old codes are not applicable since they are not reliability-based. The increasing need for assessment and renovation of existing constructions yields the necessity to develop new approaches for old materials and products that are consistent with the requirements of current codes. In this scenario, the aim of this article is to develop a new semi-empirical formulation for anchorage and lap strength of plain surface bars of R.C. structures that is also consistent with the reliability-based approach included in the forthcoming second generation of Eurocodes. To this aim, by using a reference test database, a novel step-by-step procedure is proposed for the statistical evaluation and optimization of the contribution of each parameter affecting anchorage and lap strength. Moreover, the probabilistic calibration of the proposed expressions is performed and equations for design anchorage and lap strength are proposed. These equations have the same format as that, for ribbed bars, included in the latest draft of the second-generation Eurocode 2. Finally, the proposed formulations are compared with those of previous studies and earlier codes.

A light-addressable potentiometric sensor (LAPS) is a chemical sensor with a field-effect structure based on semiconductor. Its response to the analyte concentration is read out in the form of a photocurrent generated by illuminating the semiconductor with a modulated light beam. As stated in its name, a LAPS is capable of spatially resolved measurement using a scanning light beam. Recently, it has been pointed out that a part of the signal current is lost by the return current due to capacitive coupling between the solution and the semiconductor, which may seriously affect the sensor performance such as the signal-to-noise ratio, the spatial resolution, and the sensitivity. In this study, a circuit model for the return current is proposed to study its dependence on various parameters such as the diameter of contact area, the modulation frequency, the specific conductivity of the solution, and the series resistance of the circuit. It is suggested that minimization of the series resistance of the circuit is of utmost importance in order to avoid the influence of the return current. The results of calculation based on this model are compared with experimental results, and its applicability and limitation are discussed.

To measure the ion activities of cells, an easy-access and fully-integrated system is necessary in culture room with high cleanness and easy maintenance. A new sensor structure integrated with readout system based on light-addressable potentiometric sensor (LAPS) to quantitatively monitor real-time cell activity with the advantages of label free and 2D image ability is proposed. The difference of cell number and acidification could be easily observed by 2D images by means of this proposed methodology.

To investigate the ion activities of cells based on light-addressable potentiometric sensor (LAPS) platform, various high-dielectric constant sensing membrane were investigated the visibility and potential issue. Three different kinds of well-proven materials in semiconductor industry, such as Si3N4, NbOx, and TiN, are the promising sensing membranes to directly culture C3A cells. TiN and NbOx could be the potential candidate. The photocurrent and flatband voltage difference generated by acidification reaction is verified to observe by LAPS is the future.

Micro particles and nanoparticles applied in microfluidics became a popular direction to improve biochip performance. Magnetic beads are the well-studied carriers including manipulation and surface modification, which could be easily to apply in biosensor development. A new methodology combined the actuators and sensor in the same chip all trigged by illumination is proposed in this study. A microfluidic chip with a-Si:H layer and ITO/glass with proper operation could be used to collect magnetic beads firstly and then following the optoelectrical measurement. In the meantime, 2D images for clusters of magnetic beads can be easily achieved with the addressable illumination. This proposed platform could own the high potential for a sensor array with better sensing performance.

A light-addressable potentiometric sensor (LAPS) is a semiconductor electrochemical sensor based on the field-effect which detects the variation of the Nernst potential on the sensor surface, and the measurement area is defined by illumination. Thanks to its light-addressability feature, an LAPS-based chemical imaging sensor system can be developed, which can visualize the two-dimensional distribution of chemical species on the sensor surface. This sensor system has been used for the analysis of reactions and diffusions in various biochemical samples. In this review, the LAPS system set-up, including the sensor construction, sensing and substrate materials, modulated light and various measurement modes of the sensor systems are described. The recently developed technologies and the affecting factors, especially regarding the spatial resolution and temporal resolution are discussed and summarized, and the advantages and limitations of these technologies are illustrated. Finally, the further applications of LAPS-based chemical imaging sensors are discussed, where the combination with microfluidic devices is promising.

A new high throughput screening method to characterise alloys used as gate metal of Metal/solid Electrolyte/Insulator/Semiconductor (MEIS) gas-sensors was developed. Samples with continuous gradients in alloy concentration for the system Pd 1-x-y Ni y Co y were analysed regarding H2 sensitivity. First results showed reduced poisoning effects of H2S for Ni concentrations between 4-11 at-% in Pd.

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 current–voltage characteristics and the pH sensitivity were investigated and pH imaging with this miniaturized system was demonstrated.

An analytical system for multicomponent analysis of liquids based on a light addressable potentiometric sensor (LAPS) with an array of ion-sensitive polymer membranes is presented. A developed LAPS device is based on a BESOI wafer which permits easy fabrication of a sensor with thin silicon membrane and enhanced spatial resolution. To generate the photocurrent the backside silicon was illuminated using a new technical approach based on a DLP (Digital Light Processing) chip used in video projectors. When a DLP chip is coordinated with a digital graphic signal, a light source, and a projection lens, its mirrors can reflect a digital image onto the LAPS surface. The developed system is shown to be able to produce light spots down to 50 μm in diameter and perform measurements at different points with programmable coordinates. To prove the functionality of the proposed method a LAPS sensor array with 60 ion-sensitive membranes of three different types was tested.

Microfabricated semiconductor devices are becoming increasingly relevant, also for the detection of biological and chemical quantities. Especially, the “marriage” of biomolecules and silicon technology often yields successful new sensor concepts. The fabrication techniques of such silicon-based chemical sensors and biosensors, respectively, will have a distinct impact in different fields of application such as medicine, food technology, environment, chemistry and biotechnology as well as information processing. Moreover, scientists and engineers are interested in the analytical benefits of miniaturised and microfabricated sensor devices. This paper gives a survey on different types of semiconductor-based field-effect structures that have been recently developed in our laboratory.

A time-of-flight-type flow-velocity sensor employing the in-situ electrochemically generation of ion-tracers is developed. The sensor consists of an ion generator and two downstream-placed pH-sensitive Ta2O5-gate ISFETs (ion-sensitive field-effect transistor) that detect generated H+- or OH--ions. The results of the developed flow-velocity sensor under different modes of ion generation are presented and discussed. By applying this ISFET-array, the time of flight, and consequently, the flow velocity can be accurately evaluated using the shift of the response curve of the respective ISFETs in the array along the time scale. A good linearity between the measured flow velocity with the ISFET-array and the delivered flow rate of the pump is observed. In addition, a possibility of flow-velocity measurements by means of a LAPS (light-addressable potentiometric sensor) is firstly demonstrated.

The EFSA’s Panel on Animal Health and Welfare (AHAW Panel) was asked to deliver a scientific opinion on the use of a low atmosphere pressure system (LAPS) for stunning poultry. Four documents were provided by the European Commission (EC) as the basis for an assessment of the extent to which the LAPS is able to provide a level of animal welfare at least equivalent to that ensured by the current allowed methods for stunning poultry. The LAPS is described as rendering poultry unconscious by gradually reducing oxygen tension in the atmosphere leading to progressive hypoxia in the birds. In order to be allowed in the EU, new stunning methods must ensure 1) absence of pain, distress and suffering until the onset of unconsciousness, and 2) that the animal remains unconscious until death. The submitted studies were peer-reviewed by the AHAW Panel as outlined in its “Guidance on the assessment criteria for studies evaluating the effectiveness of stunning intervention regarding animal protection at the time of killing”. It is unclear from the submitted documents whether the rate of decompression used in LAPS induces unconsciousness and death without causing avoidable pain and suffering in poultry. The assessed studies did not pass the eligibility assessment and, therefore, no further assessment was undertaken.

Myhre syndrome is characterized by short stature, brachydactyly, facial features, pseudomuscular hypertrophy, joint limitation and hearing loss. We identified SMAD4 mutations as the cause of Myhre syndrome. SMAD4 mutations have also been identified in laryngotracheal stenosis, arthropathy, prognathism and short stature syndrome (LAPS). This study aimed to review the features of Myhre and LAPS patients to define the clinical spectrum of SMAD4 mutations. We included 17 females and 15 males ranging in age from 8 to 48 years. Thirty were diagnosed with Myhre syndrome and two with LAPS. SMAD4 coding sequence was analyzed by Sanger sequencing. Clinical and radiological features were collected from a questionnaire completed by the referring physicians. All patients displayed a typical facial gestalt, thickened skin, joint limitation and muscular pseudohypertrophy. Growth retardation was common (68.7%) and was variable in severity (from -5.5 to -2 SD), as was mild-to-moderate intellectual deficiency (87.5%) with additional behavioral problems in 56.2% of the patients. Significant health concerns like obesity, arterial hypertension, bronchopulmonary insufficiency, laryngotracheal stenosis, pericarditis and early death occurred in four. Twenty-nine patients had a de novo heterozygous SMAD4 mutation, including both patients with LAPS. In 27 cases mutation affected Ile500 and in two cases Arg496. The three patients without SMAD4 mutations had typical findings of Myhre syndrome. Myhre-LAPS syndrome is a clinically homogenous condition with life threatening complications in the course of the disease. Our identification of SMAD4 mutations in 29/32 cases confirms that SMAD4 is the major gene responsible for Myhre syndrome.

Submitted by Fátima Piedade (piedade.fatima@gmail.com) on 2011-11-24T18:17:02Z No. of bitstreams: 1 Field Effect and Light-Assisted a-Si - H Sensors for Detection of Ions in Solution_rep.pdf: 52993 bytes, checksum: accd7a6d586e5c27f860ae174e223a38 (MD5) Made available in DSpace on 2011-11-24T18:17:02Z (GMT). No. of bitstreams: 1 Field Effect and Light-Assisted a-Si - H Sensors for Detection of Ions in Solution_rep.pdf: 52993 bytes, checksum: accd7a6d586e5c27f860ae174e223a38 (MD5) Previous issue date: 2010-06

To improve the spatial resolution of the light-addressable potentiometric sensor (LAPS), it is necessary to reduce the thickness of the semiconductor layer, which, however, causes a problem of the mechanical strength of the sensor plate. In this study, a thin-film LAPS was fabricated with amorphous silicon (a-Si) deposited on a transparent glass substrate. The current-voltage characteristics and pH sensitivity of the fabricated a-Si LAPS were investigated.

The integration of sensors in microfluidic systems is of special interest to build up lab-on-chip devices or micro-total-analysis-systems (μTAS). Those systems allow quick and cost-effective analysis with a minimum need of sample volumes. One drawback of present systems is the rigid sensor layout which has to be defined early during the design and the manufacturing of a new lab-on-chip system. This work will present the utilization of a light-addressable potentiometric sensor (LAPS) in combination with a microfluidic set-up, for the flexible adjustment of the size, the shape and the location of sensor spots at operation time.

The light-addressable potentiometric sensor (LAPS) has the unique feature to address different regions of a sensor surface without the need of complex structures. Measurements at different locations on the sensor surface can be performed in a common analyte solution, which distinctly simplifies the fluidic set-up. However, the measurement in a single analyte chamber prevents the application of different drugs or different concentrations of a drug to each measurement spot at the same time as in the case of multi-reservoir-based set-ups. In this work, the authors designed a LAPS-based set-up for cell culture screening that utilises magnetic beads loaded with the endotoxin (lipopolysaccharides, LPS), to generate a spatially distributed gradient of analyte concentration. Different external magnetic fields can be adjusted to move the magnetic beads loaded with a specific drug within the measurement cell. By recording the metabolic activities of a cell layer cultured on top of the LAPS surface, this work shows the possibility to apply different concentrations of a sample along the LAPS measurement spots within a common analyte solution. Keywords: LAPS, Macrophages, Lipopolysaccharides (LPS), Magnetic beads, Field-effect, Biosensor

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.

In this paper, a numerical simulation technique suitable for device-level analysis of ion-sensitive devices (ion-sensitive field-effect-transistor (ISFET) and light-addressable potentiometric sensor (LAPS)) is presented. Models of the charge layers which develop at the electrolyte–insulator interface of an electrolyte insulator-semiconductor (EIS) system are incorporated into the device equations, thus providing a self-consistent picture of charge and field distribution within the semiconductor domain. To accomplish the simulation of LAPS devices, an AC-modulated optical generation rate has been introduced as well. A TCAD tool, based on the proposed approach, has been developed, which allows for the electrical characterization and for the extraction of circuit-simulation parameters of ion-sensitive devices. Validation of the device-analysis technique comes from the comparison between predicted electrical responses and actual device measurements.