Publications by authors named "Leleux P"

Beehive health monitoring has gained interest in the study of bees in biology, ecology, and agriculture. As audio sensors are less intrusive, a number of audio datasets (mainly labeled with the presence of a queen in the hive) have appeared in the literature, and interest in their classification has been raised. All studies have exhibited good accuracy, and a few have questioned and revealed that classification cannot be generalized to unseen hives.

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Among legumes (Fabaceae) capable of nitrogen-fixing nodulation, several Aeschynomene spp. use a unique symbiotic process that is independent of Nod factors and infection threads. They are also distinctive in developing root and stem nodules with photosynthetic bradyrhizobia.

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Organic electrochemical transistors (OECTs) are receiving a great deal of attention as amplifying transducers for electrophysiology. A key limitation of this type of transistors, however, lies in the fact that their output is a current, while most electrophysiology equipment requires a voltage input. A simple circuit is built and modeled that uses a drain resistor to produce a voltage output.

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Koi herpesvirus disease (KHVD) is an emerging disease that causes mass mortality in koi and common carp, L. Its causative agent is Cyprinid herpesvirus 3 (CyHV-3), also known as koi herpesvirus (KHV). Although data on the pathogenesis of this deadly virus is relatively abundant in the literature, still little is known about its genomic diversity and about the molecular mechanisms that lead to such a high virulence.

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Aeschynomene evenia has emerged as a new model legume for the deciphering of the molecular mechanisms of an alternative symbiotic process that is independent of the Nod factors. Whereas most of the research on nitrogen-fixing symbiosis, legume genetics and genomics has so far focused on Galegoid and Phaseolid legumes, A. evenia falls in the more basal and understudied Dalbergioid clade along with peanut (Arachis hypogaea).

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Unlabelled: Despite recent interest in organic electrochemical transistors (OECTs), sparked by their straightforward fabrication and high performance, the fundamental mechanism behind their operation remains largely unexplored. OECTs use an electrolyte in direct contact with a polymer channel as part of their device structure. Hence, they offer facile integration with biological milieux and are currently used as amplifying transducers for bioelectronics.

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We report the fabrication of three dimensional (3D) macroporous scaffolds made from poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) via an ice-templating method. The scaffolds offer tunable pore size and morphology, and are electrochemically active. When a potential is applied to the scaffolds, reversible changes take place in their electrical doping state, which in turn enables precise control over the conformation of adsorbed proteins ( fibronectin).

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Electrical, label-free monitoring of cells is a non-invasive method for dynamically assessing the integrity of cells for diagnostic purposes. The organic electrochemical transistor (OECT) is a device that has been demonstrated to be advantageous for interfacing with biological systems and had previously been shown to be capable of monitoring electrically tight, resistant, barrier type tissue. Herein, the OECT is demonstrated not only for monitoring of barrier tissue cells such as MDCK I, but also for other, non-barrier tissue adherent cells including HeLa cells and HEK epithelial cells.

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Organic electrochemical transistors are integrated on depth probes to achieve localized electrical stimulation of neurons. The probes feature a mechanical delamination process which leaves only a 4 μm thick film with embedded transistors inside the brain. This considerably reduces probe invasiveness and correspondingly improves future brain-machine interfaces.

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Impedance sensing of biological systems allows for monitoring of cell and tissue properties, including cell-substrate attachment, layer confluence, and the "tightness" of an epithelial tissue. These properties are critical for electrical detection of tissue health and viability in applications such as toxicological screening. Organic transistors based on conducting polymers offer a promising route to efficiently transduce ionic currents to attain high quality impedance spectra, but collection of complete impedance spectra can be time consuming (minutes).

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The organic electrochemical transistor (OECT) is a unique device that shows great promise for sensing in biomedical applications such as monitoring of the integrity of epithelial tissue. It is a label-free sensor that is amenable to low-cost production by roll-to-roll or other printing technologies. Herein, the optimization of a planar OECT for the characterization of barrier tissue is presented.

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An organic electrochemical transistor operates in accumulation mode with high transconductance. The channel comprises a thiophene-based conjugated polyelectrolyte, which is p-type doped by anions injected from a liquid electrolyte upon the application of a gate voltage. The use of ethylene glycol as a co-solvent dramatically improves the transconductance and the temporal response of the transistors.

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The ability of organic electrochemical transistors is explored to record human electrophysiological signals of clinical relevance. An organic electrochemical transistor (OECT) that shows a high (>1 mS) transconductance at zero applied gate voltage is used, necessitating only one power supply to bias the drain, while the gate circuit is driven by cutaneous electrical potentials. The OECT is successful in recording cardiac rhythm, eye movement, and brain activity of a human volunteer.

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A planar, conducting-polymer-based transistor for combined optical and electronic monitoring of live cells provides a unique platform for monitoring the health of cells in vitro. Monitoring of MDCK-I epithelial cells over several days is shown, along with a demonstration of the device for toxicology studies, of use in future drug discovery or diagnostics applications.

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The integration of an ionic liquid gel on conformal electrodes is investigated for applications in long-term cutaneous recordings. Electrodes made of Au and the conducting polymer PEDOT:PSS coated with the gel show a low impedance in contact with the skin that maintains a steady value over several days, paving the way for non-invasive, long-term monitoring of human electrophysiological activity.

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Ion flow across polarized epithelia is a tightly regulated process. Measurement of the transepithelial resistance is a highly relevant parameter for assessing the function or health of the tissue. Dynamic, electrical measurements of transepithelial ion flow are preferred as they provide the most accurate snapshot of effects of external stimuli.

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By varying device geometry we have engineered organic electrochemical transistors that exhibit their maximum transconductance at zero gate bias. This enables the design of a simplified amplifying transducer, allowing for improved integration with biomedical systems where prolonged gate bias can be detrimental.

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Conducting polymer electrodes are developed on a flexible substrate for electroencephalography applications. These electrodes yield higher quality recordings than dry electrodes made from metal. Their performance is equivalent to commercial gel-assisted electrodes, paving the way for non-invasive, long-term monitoring of the human brain.

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The development of transistors with high gain is essential for applications ranging from switching elements and drivers to transducers for chemical and biological sensing. Organic transistors have become well-established based on their distinct advantages, including ease of fabrication, synthetic freedom for chemical functionalization, and the ability to take on unique form factors. These devices, however, are largely viewed as belonging to the low-end of the performance spectrum.

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Using planar junctions between the conducting polymer PEDOT:PSS and various electrolytes, it is possible to inject common ions and directly observe their transit through the film. The 1D geometry of the experiment allows a straightforward estimate of the ion drift mobilities.

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In vivo electrophysiological recordings of neuronal circuits are necessary for diagnostic purposes and for brain-machine interfaces. Organic electronic devices constitute a promising candidate because of their mechanical flexibility and biocompatibility. Here we demonstrate the engineering of an organic electrochemical transistor embedded in an ultrathin organic film designed to record electrophysiological signals on the surface of the brain.

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