A review of nanocomposite-modified electrochemical sensors for water quality monitoring

Electrochemical sensors play a significant role in detecting chemical ions, molecules, and pathogens in water and other applications. These sensors are sensitive, portable, fast, inexpensive, and suitable for online and in-situ measurements compared to other methods. They can provide the detection for any compound that can undergo certain transformations within a potential window. It enables applications in multiple ion detection, mainly since these sensors are primarily non-specific. In this paper, we provide a survey of electrochemical sensors for the detection of water contaminants, i.e., pesticides, nitrate, nitrite, phosphorus, water hardeners, disinfectant, and other emergent contaminants (phenol, estrogen, gallic acid etc.). We focus on the influence of surface modification of the working electrodes by carbon nanomaterials, metallic nanostructures, imprinted polymers and evaluate the corresponding sensing performance. Especially for pesticides, which are challenging and need special care, we highlight biosensors, such as enzymatic sensors, immunobiosensor, aptasensors, and biomimetic sensors. We discuss the sensors’ overall performance, especially concerning real-sample performance and the capability for actual field application

Optimized design and performance analysis of wearable antenna sensors for wireless body area network applications

ABSTRACTOver the past decade, the continuous development and the high level of maturity of wireless sensor networks resulted in new networks called wireless body area networks (WBANs), which are an emerging sector of biomedical technology. Moreover, this field has gained significant attention due to its applications which mainly are toward biomedical and healthcare applications. Nowadays, small sensors that can transfer data to other devices can now be implanted anywhere on the human body to record different physiological indicators and enable further actions to be conducted, such as processing, remote procedures and decision aided. Considering this recent hot subject, the intent of this work is to present a new approach of the optimized design and the performance analysis of WBAN specifically channel modelling between wearable wireless sensors. The behaviour of these sensors on the human body is theoretically and experimentally explored in detail along this paper. A good agreement is obtained between the theoretical and the experimental results, although the complexity of the physiological behaviour of human body

Running transactional business processes with blockchain's smart contracts

International audienceSmart Contracts (SC for short) are gaining momentum as a suitable technology for ensuring trusted execution of Business Processes (BP for short) in open environment. Nevertheless, the transactional semantics of SC which follow ACID transactions are not appropriate for BP characteristics. Indeed, it is admitted that ACID transactions are limited to cope with complex control structure and long running execution of BP. Transactional Business Processes (TBP for short) have emerged as an extension to ACID models to overcome these limits. A TBP ensures transactional reliability of advanced transactions having a control structure as complex as for BP. In this paper, we propose an approach that builds on SC and extends them to implement TBP. We extend Caterpillar, an existing BP execution engine developed on top of Ethereum, to implement our approach and support the execution of TBP

Blockchain's fame reaches the execution of personalized touristic itineraries

International audienceBlockchain trends cover more and more tech domains making it one of the most used technologies in the lastfew years. This is due to two essential aspects. First, it is a distributed peer-to-peer network where there is no need for third part to execute operations between peers. Second, blockchain implements mechanisms to make the most data sensitive operations executed in a trusted way. Regarding these attractive aspects, we intend in this work to use the blockchain technology for the implementation of touristic itineraries. We consider the latter as process choreographies involving different participants. We intend to model and execute the touristic itineraries generatedfrom a personalized trip planner called CART in raw XML format in a way that respects this collaborative aspect andresolves the problem of trust. We will propose a pattern and its transformation rules to reconstruct the itineraries presented in declarative annotations such as XML to smart contracts written in some smart contract-specific programming language called Solidity. Experimental results show promising perspectives of the deployment of the proposed solution to execute touristic plans

Trustworthy Cross-Organizational Collaborations with Hybrid On/Off-Chain Declarative Choreographies

International audienceBusiness Process Management communities increasingly adopt the blockchain technology to support trustworthy decentralized execution of processes. In this context, the interest in business process choreographies rises as they offer a distributed way to compose and control cross-organizational processes. In choreographies, the process view is distributed between participants to limit privacy leakages. Hence, the process observability (i.e., who knows what) is challenging. On one side, partners have no insight into each other’s orchestration and communicate peer-to-peer via the public view. On the other side, they have to maintain their internal orchestrations’ states consistent with the choreography’s global state. The need to ensure a privacy-preserving method to enforce a blockchain-based execution thus rises. In the present work, we propose a unified solution for the hybrid on/off-chain generation and execution of business process choreographies. The public view, shared understanding of the cross-organizational process, is triggered by the on-chain smart contract. Participants generate their private views off-chain using this on-chain public view. They execute afterward the private views in their off-chain process execution engine. Our prototypical implementation demonstrates the feasibility of the approach

Stability Enhancement of Laser-Scribed Reduced Graphene Oxide Electrodes Functionalized by Iron Oxide/Reduced Graphene Oxide Nanocomposites for Nitrite Sensors

An iron oxide/reduced graphene oxide (ION-RGO) nanocomposite has been fabricated to functionalize a low-cost electrochemical nitrite sensor realized by light-scribed reduced graphene oxide (LRGO) electrodes on a PET substrate. To enhance the stability and adhesion of the electrode, the PET substrate was modified by RF oxygen plasma, and a thin layer of the cationic poly (diallyl dimethyl ammonium chloride) was deposited. Raman spectroscopy and scanning electron microscopy coupled to energy-dispersive X-ray spectroscopy (SEM-EDX) reveal that the light-scribing process successfully reduces graphene oxide while forming a porous multilayered structure. As confirmed by cyclic voltammetry, the LRGO electrochemical response to ferri-ferrocyanide and nitrite is significantly improved after functionalization with the ION-RGO nanocomposite film. Under optimized differential pulse voltammetry conditions, the LRGO/ION-RGO electrode responds linearly (R2 = 0.97) to nitrite in the range of 10–400 µM, achieving a limit of detection of 7.2 μM and sensitivity of 0.14 µA/µM. A single LRGO/ION-RGO electrode stands for 11 consecutive runs. The novel fabrication process leads to highly stable and reproducible electrodes for electrochemical sensors and thus offers a low-cost option for the rapid and sensitive detection of nitrite

A trustworthy decentralized change propagation mechanism for declarative choreographies

International audienceBlockchain technologies have emerged to serve as a trust basis for the monitoring and execution of business processes, particularly business process choreographies. However, dealing with changes in smart contract-enabled business processes remains an open issue. For any required modification to an existing smart contract (SC), a new version of the SC with a new address is deployed on the blockchain and stored in a contract registry. Moreover, in a choreography, a change in a partner process might affect the processes of other partners. Thus, the change effect must be propagated to partners of the choreography affected by the change. In this paper, we propose a new approach overcoming the limitations of SCs and allowing for the change management of blockchain-enabled declarative business process choreographies modeled as DCR graphs. Our approach allows a partner in a running blockchain-based DCR choreography instance to change its private DCR process. A change impacting other partners is propagated to their affected processes using a SC. The change propagation mechanism ensures the compatibility checks between public DCR processes of the partners. We demonstrate the approach’s feasibility through an implemented prototype

Ultra-Sensitive and Fast Humidity Sensors Based on Direct Laser-Scribed Graphene Oxide/Carbon Nanotubes Composites

In this paper, the relative humidity sensor properties of graphene oxide (GO) and graphene oxide/multiwalled nanotubes (GO/MWNTs) composites have been investigated. Composite sensors were fabricated by direct laser scribing and characterized using UV-vis-NIR, Raman, Fourier transform infrared, and X-ray photoemission spectroscopies, electron scanning microscopy coupled with energy-dispersive X-ray analysis, and impedance spectroscopy (IS). These methods confirm the composite homogeneity and laser reduction of GO/MWNT with dominant GO characteristics, while ISresults analysis reveals the circuit model for rGO-GO-rGO structure and the effect of MWNT on the sensor properties. Although direct laser scribing of GO-based humidity sensor shows an outstanding response (|ΔZ|/|Z| up to 638,800%), a lack of stability and repeatability has been observed. GO/MWNT-based humidity sensors are more conductive than GO sensors and relatively less sensitive (|ΔZ|/|Z| = 163,000%). However, they are more stable in harsh humid conditions, repeatable, and reproducible even after several years of shelf-life. In addition, they have fast response/recovery times of 10.7 s and 9.3 s and an ultra-fast response time of 61 ms when abrupt humidification/dehumidification is applied by respiration. All carbon-based sensors’ overall properties confirm the advantage of introducing the GO/MWNT hybrid and laser direct writing to produce stable structures and sensors