In this study, the combination of activated carbon with task specific ionic liquids has resulted in a unique new generation paste in which the traditional components have been replaced with alternate materials. In this study, palm shell activated carbon modified with trioctylmethylammonium salicylate was used as a novel electrode component for the potentiometric determination of cadmium ions in water samples. The proposed potentiometric sensor has good operating characteristics when used to determine Cd(II), including a relatively high selectivity; a Nernstian response in a working concentration range of 1.0×10-9 to 1.0×10-2 M, with a detection limit of 1×10-10 M and a slope of 30.90 ± 1.0 mV/decade; and a fast response time (~ 10 s). The proposed sensor can also be used for at least two months without considerable changes in its response characteristics. No significant changes in the electrode potential were observed when the pH was varied over the range of 4-9. Additionally, the proposed electrodes have been successfully used for the determination of the cadmium contents of real samples without a significant interaction from other cationic or anionic species.

MEMS parallel plate beam actuators can be comprehended within pull-in with the existence of an intermediate dielectric layer, which has a major outcome of the performance of such actuators. In this research, MEMS parallel plate actuator with an intermediate dielectric layer was simulated to study the relationship between pull-in voltage and thickness of the dielectric layer. Higher dielectric thickness gives more regular and predictable behavior, thus variable dielectric thickness was tested with a view to obtaining desired characteristic beyond pull-in. Many MEMS devices operate beyond pull-in, e.g., capacitive switches, zipper varactors, and coplanar waveguide (CPW) resonators. The actuator designed consists of two parallel plate electrodes with a dielectric layer in between, and dielectric layer with varying thickness were simulated using Intellsuite in order to observe pull-in voltage beyond 1µm displacement required

Today conventional gel electrodes are widely used for biopotential measurements (EEG, ECG,..) despite their important drawbacks, such as signal degradation due to gel drying, skin irritation and the time-consuming set-up. Dry electrodes overcome most of these problems, however, the rigidity of the existing metal and Ag/AgCl dry electrodes causes discomfort and pain. In this paper, flexible polymer-based dry electrodes with high user comfort are presented. They are fabricated from EPDM rubber with various additives for optimization of conductivity, flexibility and fabrication yield. The impedance of these electrodes is measured for various signal frequencies on phantoms to test reproducibility, and on human skin to evaluate the electrode-skin impedance variation between subjects. All the subjects reported that our polymer electrodes were not causing discomfort. The polymer electrodes with optimum composition show ~10 times larger normalized impedance than gel electrodes. Tests showed that skin-electrode impedance reduced significantly by skin hydration, but this effect is only temporally. The 10-fold higher impedance of our polymer electrodes allows for an easy recording of strong biopotential signals such as ECG. For weaker signals, like EEG, the electrodes need to be coupled with an active circuit to compensate for their higher impedance. EEG recordings using active dry electrodes combined with a clinical EEG recording system are promising: visual interpretation of the signals revealed clear alpha-waves when subjects close their eyes, and correlation and coherence analyses reveal high similarity between dry and gel electrode signals. Based on the obtained results, the polymer-based dry electrodes are promising alternatives for the rigid dry electrodes in development and the conventional gel electrodes.

Sensor networks, and more specifically wireless sensor networks (WSN), are generally used to collect information from the environment. The gathered data are mainly delivered to sinks or gateways that become the endpoints where applications can retrieve and use such data. But applications would also expect from a WSN an event-driven operational model, so that they can be notified whenever occur some specific environmental changes instead of analyzing continuously the data provided periodically.In either operational model, wireless sensor networks represent a collection of objects interconnected, in a similar way that is outlined by the Internet of Things vision. In following years sensors will become more capable and resourceful. But in the meantime, they lie into the definition of constrained devices. In addition, to fulfill the vision of the Internet of Things, they must have a virtual representation that allows indirect access to their resources, a model that should also include the virtualization of event sources in a WSN.Thus, in this paper we propose a model for a virtual representation of event sources in a WSN. The event sources are modeled as internet resources that are accessible by any internet application, following an Internet of Things approach. The model has been tested in a real implementation where a wireless sensor network has been deployed in an open neighborhood environment. Different event sources have been identified in the proposed scenario, and they have been represented following the proposed model.

The ability to optically, electrically and magnetically detect the state of biological systems and species is continually being researched. Even though optical & magnetic procedures continue to grow and evolve, electrical detection methods, by-far, continue to remain the most desirable. Nanowires (NW) have emerged as powerful platforms for creating robust, sensitive and selective electrical sensor for biological detection. These NW have been custom created & modified to be used for electrochemical biosensing, owing to their miniaturizing properties and effective recognition abilities. Moreover their 1-Dimensional morphology offers significant improvements in sensitivity & specificity.This paper specifically deals with the study of common and technologically relevant semiconductor materials, such as those of Silicon (Si) & Zinc Oxide (ZnO), which have currently become the face of interdisciplinary bio-electrochemical research. The effect of thermal annealing as well as surface defect passivation on various electrical transport properties for highly selective pathogen sensing have been discussed. Surface functionalization & fluid exchange characteristics of SiNW and ZnO based sensing channels have been observed to offer promising prospects in the discipline of Complimentary Metal-Oxide Semiconductor (CMOS) compatible Field-Effect Transistor (FET) biosensing. Operations such as DNA sensing, drug discovery and pathogen detection by the usage of semiconductor NW devices have been reviewed. Further, the paper also addresses the advantages and disadvantages of building-up such NW based electronic devices.

MEMS-based, surface mounted structural health monitoring systems were recently proposed to locate possible damage events in lightweight composite structures. To track the structural dynamics induced by the external actions, and identify in real-time the inception of drifts from the virgin, or undamaged state, recursive Bayesian filters are here adopted. As the main drawback of any on-line identification method might be linked to an excessive computing time, two solutions are jointly enforced: an order-reduction of the numerical model used to track the structural behavior, through the Proper Orthogonal Decomposition (POD) in its snapshot-based version; an improved particle filtering strategy, which features an extended Kalman updating of each evolving particle before the resampling stage. While the former method alone can reduce the number of effective degrees-of-freedom of the structure to a few only (depending on the kind of loading), the latter allows to track the evolution of damage and also locate it thanks to an intricate formulation.To assess the proposed procedure, the case of a thin plate subject to bending is investigated. It is shown that, when the procedure is fed by measurements gathered by a network of inertial MEMS sensors appropriately deployed over the plate, damage is efficiently and accurately estimated and located.

BDS regional system has been officially announced to provide positioning services over the Asia-pacific region at present. We investigate the performance of ambiguity resolution with combined GPS/BDS observations under this condition. Using observation data of the different-length short baselines and PANDA software analyze the success rate of ambiguity-fixing of GPS single system, BDS single system and GPS/BDS combined system, we find that the ambiguity of GPS/BDS combined system relative to each single system can be quickly fixed even if with L1 observation. Combine the theory of ambiguity resolution to analyze experimental results, and interpret the experimental conclusions in theory. The impact of system bias on ambiguity resolution of GPS/BDS combined system has been discussed. According to the experiment, we find the difference among fractional parts of the between-receiver SD-ambiguities is very small in the each single system, but the fractional parts of DD-ambiguities between GPS and BDS are big, however, which are stable. This provide a possibility to form DD-ambiguities by mixing SD-ambiguities of GPS and BDS by calibrating the system bias, which is highly beneficial for positioning under severe environment.

Multi-agent systems (MAS) can be used for a decentralized and self-organizing approach of data processing in a distributed system like a sensor network, enabling information extraction, for example, based on pattern recognition, decomposing complex tasks in simpler cooperative agents. MAS-based data processing approaches can aid the Material-integration of Structural-Health-Monitoring applications, with agent processing platforms scaled to microchip level which offer material-integrated real-time sensor processing.The behaviour model of mobile agents suitable for sensor network operations bases on an activity-transition graph (ATG) and is implemented with stack-based program code holding the control and data state of an agent, which can be modified by the agent itself using code morphing techniques, and which is capable to migrate in the network between nodes. The program code is a self contained unit (a container) and embeds the agent data, the initialization instructions, and the ATG. The agent processing platform used for the execution of the agent code is a pipelined multi-stack virtual machine with a zero-operand instruction format, leading to small sized agent program code, low system complexity, and high system performance. Agents processed on one particular network node can interact by using a tuple-space database provided by each sensor node. Remote interaction is provided by propagating signals carrying data. This approach provides a high degree of computational independency from the underlying platform and other agents, and enhanced robustness of the entire heterogeneous environment in the presence of node, sensor, link, data processing, and communication failures. Support for heterogeneous networks considering hardware (System-on-Chip designs) and software (microprocessor) platforms is covered by one design and high-level synthesis flow including functional behavioural simulation.An even-based sensor data processing MAS is used as a test case for the proposed agent processing platform and a microchip level implementation. The sensor data pre-processing MAS delivers sensor data event-based if a change of the sensors was detected (based on pattern recognition), reducing network activity and energy consumption significantly.

Comb-drive micromirrors are becoming of interest for a broad range of light manipulation applications. For some of these applications a vacuum packaging, which is able to guarantee higher quality factors, turns out to be not favorable for technical and functional reasons. Furthermore, micromirrors for picoprojectors application are required to function at high frequencies in order to achieve high resolution images. Accordingly, a study of the energy dissipated due to the interaction between the moving parts of the micromirror and the surrounding air, leading to fluid damping, is an important issue. Even if air damping has been thoroughly studied, an extension to large air domain distortion linked to large tilting angles of torsional micromirrors, is still partially missing. In such situations, the flow formation turns out to be far more complex than that assumed in analytical models. This task is here pursued by adopting three-dimensional computational fluid dynamics models; specifically, two models, holding at different length scales, are adopted to attack the problem through an automated dynamic remeshing method. The time evolution of the torque required to compensate for the fluid damping term is computed for a specific micromirror geometry. The relative contributions due to drag, shear and squeeze film terms are calculated as well. These results are shown to compare well with the available experimental data in terms of the overall sensor quality factor.

In this study, a new simple and low-cost plastic optical fiber sensor for the measurements of low concentration HF vapors is described. The sensitivity to the HF vapors obtained by deposing a thin glass-like layer onto the PMMA core fiber after removing the fluorinated polymer cladding via dipping the fiber into ethyl acetate for a short period, not more than 40 second. Moreover, in order to enhance the fiber sensitivity, low pressure plasma treatments have been carried out in O2 and Ar gas mixtures, on polymeric optical core fibers in order to increase the core surface area without damaging the PMMA core fiber. The reaction of glass-like layer with the HF vapor alters the fiber light transmission and is detected by means of a wide-band photodiode. The sensor used in this research has several advantages; mainly the ability to evaluate directly the cumulative exposure and the transducer is based on a plastic optical fiber. The POF sensors are designed to monitor low concentration of gaseous pollutants in the RPC (Resistive Plate Chamber) muon detector of the Compact Muon Solenoid (CMS) experiment at the CERN in Geneva and also can be used both in civil and industrial field. Several prototypes of fiber sensors have been fabricated and characterized in the reaction chamber. The obtained results demonstrating the capability to detect low concentration of HF vapors with high sensitivity.