Collaboration at the PhD thesis of J. Director : B. Responsible for the in situ monitoring of trace metal speciation. Consultant for the Governmental Institutes Magistrato alle Acque and Consorzio Venezia Nuova of Venice-Italy for the analysis and speciation of the trace elements and the interpretation of the annual whole data bank. Project of the General Oceanic company and the SeaKeepers Society - Miami-USA : "Monitoring and protecting the health of the world's oceans by equipping yachts, vessels and platforms around the world with sophisticated ocean and weather monitoring modules".
Consultant for the development, tests and optimization of an on-line metal analyzer. EU Brite-EuRam program, Collaboration for a Canadian National Project - Prof. Tercier-Waeber M. Fabry, J. Fouletier Eds. Submersible voltammetric probes for in situ real-time trace element monitoring in natural aquatic systems, Ch. Taillefert, T. Rozan Eds. Buffle J. In situ voltammetry: concepts and practice for trace analysis and speciation, chap. Buffle, G. Hoarvai Eds. Integrated electrochemical microsensors and microsystems for direct reliable chemical analysis of compounds in complex aqueous solutions.
US Patent number : 5,,, Mobilization and complexation of Zn and Cd in the rhizosphere of Thlaspi caerulescens, Env. In situ monitoring of the diurnal cycling of the dynamic metal species in a stream under contrasting photobenthic biofilm activity and hydrological conditions. Braungardt C. Analysis of dissolved metal fractions in coastal waters : An intercomparison of five voltammetric in siotu profiling VIP systems.
Dallemagne P. Kooistra L. Metal solubility and speciation in the rhizosphere of Lupinus albus. Remote in situ voltammetric techniques to characterize the biogeochemical cycling of trace metals in aquatic systems. Invited review.
Electronics Engineering - ISTE
Journal of Environmental Monitoring, 10 Gel-integrated voltammetric microsensors and submersible probes as reliable tools for environmental trace metal analysis and speciation. Electroanalysis, 20 Highlights of analytical chemistry in Switzerland - analytical concepts and tools for speciation studies. Chimia 62 Speciation analysis of Cu, Pb, Cd and Zn in soil solutions by square wave anodic stripping voltammetric technique with gel integrated microelectrode arrays.
In: Luster, J. Handbook of methods used in rhizosphere research. Integrated micro-analytical system for simultaneous voltammetric measurements of free metal ion concentrations in natural waters. Electroanalysis, 18 Speciation analysis of Cu, Pb, Cd and Zn in soil solutions.
Handbook of methods used in rhizosphere research - Understanding and modelling plant-soil interections in the rhisosphere environment, in press. Unsworth E. W, Zhang H. Model predictions of metal speciation in freshwaters compared to measurements by in situ techniques.
Chemical and Biological Microsensors: Applications in Fluid Media
Sigg L. Comparison of analytical techniques for dynamic trace metal speciation in natural freshwaters. Multi Physical-Chemical Profiler for real-time in situ monitoring of trace metal speciation and master variables: development, validation and field application. Voltammetric environmental trace-metal analysis and speciation : from laboratory to in situ measurements. Trends in Analytical Chemistry, 24 IV France, Noel S. Pauwels H. Chemical characteristics of groundwaters at two massive sulphide deposits in an area of previous mining contamination, South Iberian Pyrite Belt, Spain.
Parthasarathy N. On-line coupling of flow through voltammetric microcell to hollow fiber permeation liquid membrane device for subnanomolar trace metal speciation measurements. For example, in the work of Gong et al. The AuNWs were coated on a soft tissue paper, leading to an assembly with rough, porous surfaces filled with interlocking AuNWs. The number of AuNW—electrode pairs contributing to the changes in the electrical parameters of the sensor varied according to the external pressure applied. More specifically, upon the application of an external force, the AuNW-coated tissue paper underwent a compressive deformation, which led to an increase in the amount of AuNWs bridging the finger electrodes, resulting in a higher number of conductive pathways and an increased sensor current.
Upon unloading, the reverse occurred. Owing to the recovery of the tissue paper to its original shape, the amount of AuNWs in contact with the electrodes decreased, reducing the sensor current. Deformation-based physical sensing mechanisms.
Schematic illustration depicting the pressure-induced deformation-based working mechanism of the sensor. Schematic illustration showing the circuit model describing the pressure-induced deformation-based sensing principle of the device and the finite element analysis illustrating the distribution of stress on the micropyramid-based electrode upon the application of external pressure. Schematic illustration showing the interfacial capacitive sensing principle of the IMA flexible tactile sensor. Schematic illustration showing the operating principle of the CNT fiber-based strain sensor under different strain regimes.
Schematic illustration showing the normal and shear force detection capability of the interlocked microdome arrays based on the distinct surface deformation of the microdomes upon the application of different forces. The same contact—noncontact pressure sensing mechanism was further explored in the latest work by Choong et al.
In that study, the group presented a highly stretchable resistive pressure sensor based on arrays of a micropyramid-patterned elastomer Figure 5b. The micropyramid elastomer with a spring-like compressible platform was first replicated from a silicon mold and subsequently grafted with the polymer-based stretchable electrode. This structural configuration served as a piezoresistive electrode in which the external pressure applied was a function of the electrical resistance change of the sensor.
The introduction of a counter electrode in contact with the piezoresistive electrode under external force completed the sensor assembly. By bridging the two electrode terminals, a voltage difference with respect to the piezoresistive electrode would induce the flow of electrical current.
In this arrangement, the eventual resistance around the pyramidal structure depended on the total resistances of the piezoresistive electrode, the counter electrode, and the contact interface. When a small pressure was exerted on the device, the counter electrode came into contact with the pyramidal peak.
This contact led to the formation of a highly resistive electrical path high R o owing to the small contact perimeter low W PEo and the thin composite polymer electrode coating low D PEo. As the contact pressure increased, the micropyramid deformed laterally, resulting in a wider electrode interface high W PE and thicker electrical current path high D PE. As such, the device displayed increased current conduction low R. Importantly, by exploiting the pressure-triggered geometrical change of the sensor and the very small shape factor of the micropyramids that is, the ratio of the compressed area the pyramidal tip to the total unloaded surface areas the triangular walls of the pyramid , the device was capable of low-pressure sensing with enhanced sensitivity.
Similarly to solid-state flexible sensing platforms, platforms utilizing liquids as the active sensing element may also acquire the desired physical data based on the force-induced variations in the electrical parameters of the sensors. For example, the IMA-sensing device developed by Nie et al. With the presented device configuration, an electrical double layer EDL with a high interfacial capacitance would be established upon direct ionic droplet-electrode contact.
This area expansion resulted in a corresponding increase in the EDL capacitance, which could be electronically detected. In addition to the pressure-induced physical sensing principle, the last several years have seen the development of highly flexible and elastic strain sensors in which variations in the electrical properties of these sensors are caused by strain force. Among the plethora of materials being considered, nanoscale carbon materials such as CNTs, with their unique capability of forming conductive networks, have been actively explored as individual strain sensing elements with high elasticity or as conductive fillers within soft polymers for detecting large strains.
Ryu et al. The magnitude of the applied strain force would be detected as a function of the resistance change of the entire device. Instead of the total electrical resistance of individual CNTs, the device resistance depended on the effective contact area between individual CNTs, as these CNTs possessed large contact resistance with each other.
In this work, the highly oriented arrays of CNT fibers were attached directly on an elastic silicone elastomer substrate. With this setup, when the device was subjected to a stretching force, a uniform stress would be distributed over the whole assembly, and the stress concentration would be simultaneously reduced. As the device was stretched further beyond its sliding limit, the CNT fibers might be disconnected. Furthermore, as the physical distance between the disconnected CNT fibers increased, the number of conductive paths decreased, whereas the number of CNT fibers forming conductive paths increased.
In addition to individual pressure- and stretch-driven electrical parameter variations, there have been increasing efforts to develop flexible sensing devices with simultaneous and multiple physical data-acquisition capabilities.
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For instance, Park et al. In fact, changes to the electrical properties of the piezoresistive device were dependent on various stretch, normal, and shear forces. Here the CNT-based composite elastomer films were first microstructured with arrays of hexagonal microdomes. Through the contact and engagement of two microdome-patterned sides, interlocked geometry was then achieved. In the interlocked microdome-based system, the surface deformation patterns of the microdomes upon the application of normal and shear forces were uniquely different owing to the different directions of the mechanical stresses.
These differences produced distinct changes in the contact resistance of the microdomes in response to the normal and shear forces. Consequently, the device was capable of detecting and differentiating the magnitude and direction of these two types of loads via their distinct sensory output patterns. Biological skin-based sensory receptors for example, mechano- and thermoreceptors gather and transmit rich streams of physical variables from the external environment 8.