Ce travail de these concerne l'etude des proprietes electrochimiques des fibres de nanotubes ... more Ce travail de these concerne l'etude des proprietes electrochimiques des fibres de nanotubes de carbone (NTC). D'une part, nous nous sommes interesses a leurs caracteristiques en tant que nouveau capteur analytique. Pour cela, une procedure de fabrication de microelectrodes au comportement stable et reproductible a ete mise en place. Puis leur comportement analytique intrinseque fut caracterise avant de proceder a des modifications de surface pour les rendre plus selectives. D'autres part, nous nous sommes interesses aux proprietes electromecaniques des fibres de NTC, soit leur comportement en tant qu'actionneur electrochimique capable de generer une deformation mecanique en reponse a une injection de charge electrique. Nous avons caracterise leurs performances en terme de contrainte et deformation mecanique generee. Des voies d'optimisation ont ete investies. Enfin, nous montrons l'influence que peut avoir l'alignement des NTC au sein de la fibre sur leu...
Circumventing poor current densities and mass transport limitation are key challenges in the engi... more Circumventing poor current densities and mass transport limitation are key challenges in the engineering of new electrochemical systems and electrodes, especially in physiological solutions where concentrations (< 0.5 mM) and diffusion coefficients of substrates are very low (< 5u10 -5 cm -2 s -1 ). Carbon in various aromatic or glassy forms is well suited for electrode materials because of
During the penetration into the soil, plant roots experience mechanical impedance changes and com... more During the penetration into the soil, plant roots experience mechanical impedance changes and come into contact with obstacles which they avoid and circumnavigate during their growth. In this work, we present an experimental analysis of a sensorized artificial tip able to detect obstacles and discriminate between different mechanical impedances in artificial and real soils. The conical shaped tip is equipped with a soft capacitive tactile sensor consisting of different elastomeric and conductive layers. Experimental results show that the sensor is robust yet sensitive enough to mechanical impedance changes in the experimented soils.
Octopus show great adhesion capabilities thanks to their suckers covering their ventral side of t... more Octopus show great adhesion capabilities thanks to their suckers covering their ventral side of their arms. Starting from biological investigation, we identified preliminary specifications for the design of innovative artificial suction cups, which could be used in the field of soft robotics. The main features of the biological sucker are maintained as leading criteria for the choice of the actuation technology and mechanism. In this preliminary work, we focused on the imitation of the functionality of the specific muscle bundles which generate suction to obtain adhesion. Dielectric Elastomers Actuators (DEA) were identified as a suitable solution. A study on materials and manufacturing techniques was made. Different possible solutions in the use of DEA are also described.
The detection of dopamine is a scientific challenge of great importance for the understanding of ... more The detection of dopamine is a scientific challenge of great importance for the understanding of neurobiological dysfunctions. However the presence of ascorbic acid at concentrations several times higher than that of dopamine and its oxidation at a very similar potential make a selective electrochemical detection difficult. Here we report the original and intrinsic selectivity of carbon nanotube (CNT) fiber microelectrodes (CNTFM) towards dopamine oxidation without significant interaction from ascorbic acid.
Poor electron transfer and slow mass transport of substrates are signifi cant rate-limiting steps... more Poor electron transfer and slow mass transport of substrates are signifi cant rate-limiting steps in electrochemical systems. It is especially true in biological media, in which the concentrations and diffusion coeffi cients of substrates are low, hindering the development of power systems for miniaturized biomedical devices. In this study, we show that the newly engineered porous microwires comprised of assembled and oriented carbon nanotubes (CNTs) overcome the limitations of small dimensions and large specifi c surface area. Their improved performances are shown by comparing the electroreduction of oxygen to water in saline buffer on carbon and CNT fi bres. Under air, and after several hours of operation, we show that CNT microwires exhibit more than tenfold higher performances than conventional carbon fi bres. Consequently, under physiological conditions, the maximum power density of a miniature membraneless glucose / oxygen CNT biofuel cell exceeds by far the power density obtained for the current state of art carbon fi bre biofuel cells. Electrolyte H 2 O O 2 ee -GOx BOD Glucose Redox polymer I Redox polymer II 500 nm CNT anode CNT cathode 500 nm Figure 1 | Schematic of the biofuel cell and scanning electron micrographs of CNT fi bres. ( a ) Biofuel cell. At the anode, electrons are transferred from glucose to glucose oxidase (GOx) and from GOx to redox polymer (I) and from (I) to the CNT fi bre. At the cathode, electrons are transferred from the CNT fi bre to the redox polymer (II), from (II) to BOD and from BOD to oxygen. ( b ) CNT fi bres before and ( c ) after removing PVA.
We report on the preparation and interesting electrochemical behavior of carbon nanotube fiber mi... more We report on the preparation and interesting electrochemical behavior of carbon nanotube fiber microelectrodes (CNTFM). By combining the advantages of carbon nanotubes (CNT) with those of fiber electrodes, this type of microelectrode differs from CNT modified or CNT containing composite electrodes, because it's made of only CNT without any other components like additives or binders. The active CNT surface is easily regenerated. The performance of CNTFMs has been characterized, among others, by surface modification with phosphomolybdic acid. It is shown that adsorption behavior of these catalyst molecules is highly improved with a controlled orientation of CNT. A better CNT alignment inside the fiber can be achieved by a hot stretching procedure.
ABSTRACT Carbon nanotubes are light, stiff and electroactive materials particularly promising in ... more ABSTRACT Carbon nanotubes are light, stiff and electroactive materials particularly promising in the field of actuating materials. Indeed, carbon nanotubes can expand and contract upon charge injection and be used for the development of electromechanical actuators. Carbon nanotubes can also be included in polymers to improve their properties and bring specific functionalities. When added to shape memorypolymers, carbon nanotubes yield an improved stiffness and the possibility to heat the material through Joule’s heating. Nevertheless, spatial ordering of the nanotubes is a critical issue in all these classes of actively moving materials. It is shown in this article that assembling nanotubes under the form of pure or composite fibers is an effective approach to orient carbon nanotubes on a large scale along a well defined direction. Nanotube alignment achieved via fiber drawing allows the optimization of properties of shape memorypolymer fibers and electrochemical actuators. In particular, the mechanical response of pure nanotube fibers to electrical stimulations is investigated in liquid electrolytes. It is observed that the fibers can generate a stress one order of magnitude greater than that achieved with unaligned assemblies of nanotubes. We also present the properties of shape memorypolymer fibers loaded with carbon nanotubes. These fibers generate a very large stress when they recover their shape after they have been stretched and cooled under tensile load. Composite nanotubepolymer fibers also exhibit a temperature memory behavior, which is still raising fundamental questions regarding its microscopic origin.
The preparation and interesting electrochemical properties of carbon nanotube (CNT) fiber microel... more The preparation and interesting electrochemical properties of carbon nanotube (CNT) fiber microelectrodes are reported. By combining the advantages of CNT with those of fiber electrodes, this type of microelectrode differs from CNT-modified or CNT-containing composite electrodes, because they are made solely of CNT without other components, for example additives or binders. The performance of these electrodes has been characterized with regard to, among others, the electrocatalytic oxidation of analytes via dehydrogenase-mediated reactions. In this context the reversible regeneration of the coenzyme NAD + using a mediator is a key step in the development of new amperometric sensor devices and we have successfully immobilized mediator molecules that are very efficient for this purpose on the surface of the CNT fiber electrode. The microelectrodes thus obtained have been compared with classic carbon microelectrodes and have promising behavior in biosensing applications, especially after specific pretreatments such as CNT alignment inside the fiber or expansion of the specific surface by chemically induced swelling.
using liquid capacitors to address deformability. Here we show the fast and easy fabrication of a... more using liquid capacitors to address deformability. Here we show the fast and easy fabrication of a fully fl exible capacitive threeaxial force sensor made with conductive fabric electrodes and an elastomeric material. This unique sensor presented a high compliance, robustness and stability under manipulation and very appealing performances in terms of sensitivity (less than 10 mg and 8 µm, minimal detectable weight and displacement, respectively) and detection range (measured up to 190 kPa, and estimated up to 400 kPa) against the existing state-of-the-art sensors. This work intersects with the recent and exciting direction taken by the research fi eld towards smart, integrated, and fl exible electronic devices using an ancestral composite material: textile. [28][29] From less than a decade ago, an increasing number of research efforts have focused on the exploitation of the mechanical properties of textile as a substrate for the absorption or coating of organic and inorganic compounds. Whereas conductive fabrics are today already embraced by fashion and architectural designs, [ 33 ] the textile platform also opens an original means to develop future electronic and sensing devices. Importantly, this research approach holds promise for the design of soft, small sensing elements, wherever high functional integration and low cost are key elements. We used conductive fabrics to develop and validate an original concept of a small and three-dimensional robust sensor. In this work, we demonstrate that the structuring of the dielectric multilayer and the original combination of materials used gives our sensor the potential to outperform state-ofthe-art sensors by employing a fast and accessible yet robust and low-cost fabrication technology. The capacitive sensor is made of two textile electrode levels (i.e., top and bottom) of a non-stretchable copper/tin coated textile (Zelt, Mindset Ltd) separated by a fl oating fl uorosilicone (DowCorning730, 70 µm thickness) fi lm as the dielectric layer ). Its appealing intrinsic dielectric constant and mechanical properties make fl uorosilicone a suitable material for this application. In particular, because of its low adhesion features, an air gap of around 150 µm is naturally formed during fabrication in between the two copper/tin coated textile electrodes. This air gap adds a second dielectric layer to our sensor and triggers very high performances at very low pressures (ca. 0-2 kPa). The woven fabric used in this work presents two main perpendicular sets of conductive yarns (i.e. warp and weft) where the warp yarn is interlaced up and down of the weft yarn creating an opening called shed (see S1, Supporting Information). The volume of air created by the shed contributes to the formation of a third dielectric layer which plays an important role at higher pressures (>2 kPa). This unique composite structure is embedded in between two polydimethylsiloxane (PDMS) packaging layers to form a mechanically fl exible and robust capacitive sensor ). The sensor design has four square The emulation of natural touch requires tactile sensors that mechanically comply with the environment -in order to gain relevant information from physical interactions -and that, at the same time, are able to perform when smoothly adapted to host three-dimensional structures. For this purpose, successive solutions have been attempted. However, to shape deformable materials while developing high precision, yet robust, systems is complex, and it reveals interesting scientifi c questions in addition to technological challenges. As a result, fl exible tactile sensors can present a very high pressure sensitivity, but the low saturation level (less than 50 kPa), intrinsically imposed by their architecture and/or manufacturing technology, limits their applications. Moreover, one fundamental function is still being overlooked, and that is the detection of contact force not only in the normal direction to the sensor/object interface, but also in the tangential direction. This would raise the level of encoded information by an artifi cial touch system closer to natural touch, for instance, slippage and texture detection. However, in comparison to pressure sensitive devices, or combined pressure and strain sensors, only a small number of skin-like sensors that can sense normal and tangential forces has been presented in the literature. In this context, stateof-the-art developments expose two main challenges: on the one hand, highly sensitive and fl exible devices able to detect forces in three dimensions over a large force range are pursued; whereas on the other hand, which is more economically related, their fabrication on large areas is requested. Original alternative sensor designs, using soft materials and processes have been shown to skirt those aspects and/or simplify fabrication processes. Among these, capacitive-based sensors show good potential towards deformable tactile sensors. In particular, Surapaneni et al. have demonstrated very high force range detection (up 320 kPa) and minimum detectable displacement of 60 µm using gold fl oating electrodes in comb-like structures, whereas other groups, in particular, Noda et al. have introduced original approaches for three-axis force detection [+] These authors contributed equally to this work. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
In drug therapy, most therapeutic drugs are of low molecular weight and could freely diffuse in t... more In drug therapy, most therapeutic drugs are of low molecular weight and could freely diffuse in the biological milieu depending on the administration route applied. The main reason for the development of polymeric drug carriers is to obtain desired effects such as sustained therapy, local and controlled release, prolonged activity and reduction of side effects. Alternatively, polymeric carriers can be made bioerodible in order to be eliminated by natural ways after a certain time of therapy. Core-shell fibres from coaxial spinneret or emulsion electrospinning are good candidates for the development of such devices; however difficulties remain especially in controlling the release over a sustained period. Here, we present a novel technique combining coaxial and emulsion electrospinning to produce microstructured core-shell fibres. The design of drug microreservoirs of variable size within the bulk of the fibre combined with a tailored diffusive barrier allows modulating the release kinetics of these novel carriers. A nearly constant and linear release of the model drug Levetiracetam (M w z 170 g mol À1 ) from PLGA emulsion-coaxial electrospun fibres is observed over 20 days. This device is aimed to be implanted into the brain for the treatment of epilepsy and is an example of the new capabilities and the promising potential that emulsion-coaxial electrospinning can provide towards the development of future drug carriers.
Ce travail de these concerne l'etude des proprietes electrochimiques des fibres de nanotubes ... more Ce travail de these concerne l'etude des proprietes electrochimiques des fibres de nanotubes de carbone (NTC). D'une part, nous nous sommes interesses a leurs caracteristiques en tant que nouveau capteur analytique. Pour cela, une procedure de fabrication de microelectrodes au comportement stable et reproductible a ete mise en place. Puis leur comportement analytique intrinseque fut caracterise avant de proceder a des modifications de surface pour les rendre plus selectives. D'autres part, nous nous sommes interesses aux proprietes electromecaniques des fibres de NTC, soit leur comportement en tant qu'actionneur electrochimique capable de generer une deformation mecanique en reponse a une injection de charge electrique. Nous avons caracterise leurs performances en terme de contrainte et deformation mecanique generee. Des voies d'optimisation ont ete investies. Enfin, nous montrons l'influence que peut avoir l'alignement des NTC au sein de la fibre sur leu...
Circumventing poor current densities and mass transport limitation are key challenges in the engi... more Circumventing poor current densities and mass transport limitation are key challenges in the engineering of new electrochemical systems and electrodes, especially in physiological solutions where concentrations (< 0.5 mM) and diffusion coefficients of substrates are very low (< 5u10 -5 cm -2 s -1 ). Carbon in various aromatic or glassy forms is well suited for electrode materials because of
During the penetration into the soil, plant roots experience mechanical impedance changes and com... more During the penetration into the soil, plant roots experience mechanical impedance changes and come into contact with obstacles which they avoid and circumnavigate during their growth. In this work, we present an experimental analysis of a sensorized artificial tip able to detect obstacles and discriminate between different mechanical impedances in artificial and real soils. The conical shaped tip is equipped with a soft capacitive tactile sensor consisting of different elastomeric and conductive layers. Experimental results show that the sensor is robust yet sensitive enough to mechanical impedance changes in the experimented soils.
Octopus show great adhesion capabilities thanks to their suckers covering their ventral side of t... more Octopus show great adhesion capabilities thanks to their suckers covering their ventral side of their arms. Starting from biological investigation, we identified preliminary specifications for the design of innovative artificial suction cups, which could be used in the field of soft robotics. The main features of the biological sucker are maintained as leading criteria for the choice of the actuation technology and mechanism. In this preliminary work, we focused on the imitation of the functionality of the specific muscle bundles which generate suction to obtain adhesion. Dielectric Elastomers Actuators (DEA) were identified as a suitable solution. A study on materials and manufacturing techniques was made. Different possible solutions in the use of DEA are also described.
The detection of dopamine is a scientific challenge of great importance for the understanding of ... more The detection of dopamine is a scientific challenge of great importance for the understanding of neurobiological dysfunctions. However the presence of ascorbic acid at concentrations several times higher than that of dopamine and its oxidation at a very similar potential make a selective electrochemical detection difficult. Here we report the original and intrinsic selectivity of carbon nanotube (CNT) fiber microelectrodes (CNTFM) towards dopamine oxidation without significant interaction from ascorbic acid.
Poor electron transfer and slow mass transport of substrates are signifi cant rate-limiting steps... more Poor electron transfer and slow mass transport of substrates are signifi cant rate-limiting steps in electrochemical systems. It is especially true in biological media, in which the concentrations and diffusion coeffi cients of substrates are low, hindering the development of power systems for miniaturized biomedical devices. In this study, we show that the newly engineered porous microwires comprised of assembled and oriented carbon nanotubes (CNTs) overcome the limitations of small dimensions and large specifi c surface area. Their improved performances are shown by comparing the electroreduction of oxygen to water in saline buffer on carbon and CNT fi bres. Under air, and after several hours of operation, we show that CNT microwires exhibit more than tenfold higher performances than conventional carbon fi bres. Consequently, under physiological conditions, the maximum power density of a miniature membraneless glucose / oxygen CNT biofuel cell exceeds by far the power density obtained for the current state of art carbon fi bre biofuel cells. Electrolyte H 2 O O 2 ee -GOx BOD Glucose Redox polymer I Redox polymer II 500 nm CNT anode CNT cathode 500 nm Figure 1 | Schematic of the biofuel cell and scanning electron micrographs of CNT fi bres. ( a ) Biofuel cell. At the anode, electrons are transferred from glucose to glucose oxidase (GOx) and from GOx to redox polymer (I) and from (I) to the CNT fi bre. At the cathode, electrons are transferred from the CNT fi bre to the redox polymer (II), from (II) to BOD and from BOD to oxygen. ( b ) CNT fi bres before and ( c ) after removing PVA.
We report on the preparation and interesting electrochemical behavior of carbon nanotube fiber mi... more We report on the preparation and interesting electrochemical behavior of carbon nanotube fiber microelectrodes (CNTFM). By combining the advantages of carbon nanotubes (CNT) with those of fiber electrodes, this type of microelectrode differs from CNT modified or CNT containing composite electrodes, because it's made of only CNT without any other components like additives or binders. The active CNT surface is easily regenerated. The performance of CNTFMs has been characterized, among others, by surface modification with phosphomolybdic acid. It is shown that adsorption behavior of these catalyst molecules is highly improved with a controlled orientation of CNT. A better CNT alignment inside the fiber can be achieved by a hot stretching procedure.
ABSTRACT Carbon nanotubes are light, stiff and electroactive materials particularly promising in ... more ABSTRACT Carbon nanotubes are light, stiff and electroactive materials particularly promising in the field of actuating materials. Indeed, carbon nanotubes can expand and contract upon charge injection and be used for the development of electromechanical actuators. Carbon nanotubes can also be included in polymers to improve their properties and bring specific functionalities. When added to shape memorypolymers, carbon nanotubes yield an improved stiffness and the possibility to heat the material through Joule’s heating. Nevertheless, spatial ordering of the nanotubes is a critical issue in all these classes of actively moving materials. It is shown in this article that assembling nanotubes under the form of pure or composite fibers is an effective approach to orient carbon nanotubes on a large scale along a well defined direction. Nanotube alignment achieved via fiber drawing allows the optimization of properties of shape memorypolymer fibers and electrochemical actuators. In particular, the mechanical response of pure nanotube fibers to electrical stimulations is investigated in liquid electrolytes. It is observed that the fibers can generate a stress one order of magnitude greater than that achieved with unaligned assemblies of nanotubes. We also present the properties of shape memorypolymer fibers loaded with carbon nanotubes. These fibers generate a very large stress when they recover their shape after they have been stretched and cooled under tensile load. Composite nanotubepolymer fibers also exhibit a temperature memory behavior, which is still raising fundamental questions regarding its microscopic origin.
The preparation and interesting electrochemical properties of carbon nanotube (CNT) fiber microel... more The preparation and interesting electrochemical properties of carbon nanotube (CNT) fiber microelectrodes are reported. By combining the advantages of CNT with those of fiber electrodes, this type of microelectrode differs from CNT-modified or CNT-containing composite electrodes, because they are made solely of CNT without other components, for example additives or binders. The performance of these electrodes has been characterized with regard to, among others, the electrocatalytic oxidation of analytes via dehydrogenase-mediated reactions. In this context the reversible regeneration of the coenzyme NAD + using a mediator is a key step in the development of new amperometric sensor devices and we have successfully immobilized mediator molecules that are very efficient for this purpose on the surface of the CNT fiber electrode. The microelectrodes thus obtained have been compared with classic carbon microelectrodes and have promising behavior in biosensing applications, especially after specific pretreatments such as CNT alignment inside the fiber or expansion of the specific surface by chemically induced swelling.
using liquid capacitors to address deformability. Here we show the fast and easy fabrication of a... more using liquid capacitors to address deformability. Here we show the fast and easy fabrication of a fully fl exible capacitive threeaxial force sensor made with conductive fabric electrodes and an elastomeric material. This unique sensor presented a high compliance, robustness and stability under manipulation and very appealing performances in terms of sensitivity (less than 10 mg and 8 µm, minimal detectable weight and displacement, respectively) and detection range (measured up to 190 kPa, and estimated up to 400 kPa) against the existing state-of-the-art sensors. This work intersects with the recent and exciting direction taken by the research fi eld towards smart, integrated, and fl exible electronic devices using an ancestral composite material: textile. [28][29] From less than a decade ago, an increasing number of research efforts have focused on the exploitation of the mechanical properties of textile as a substrate for the absorption or coating of organic and inorganic compounds. Whereas conductive fabrics are today already embraced by fashion and architectural designs, [ 33 ] the textile platform also opens an original means to develop future electronic and sensing devices. Importantly, this research approach holds promise for the design of soft, small sensing elements, wherever high functional integration and low cost are key elements. We used conductive fabrics to develop and validate an original concept of a small and three-dimensional robust sensor. In this work, we demonstrate that the structuring of the dielectric multilayer and the original combination of materials used gives our sensor the potential to outperform state-ofthe-art sensors by employing a fast and accessible yet robust and low-cost fabrication technology. The capacitive sensor is made of two textile electrode levels (i.e., top and bottom) of a non-stretchable copper/tin coated textile (Zelt, Mindset Ltd) separated by a fl oating fl uorosilicone (DowCorning730, 70 µm thickness) fi lm as the dielectric layer ). Its appealing intrinsic dielectric constant and mechanical properties make fl uorosilicone a suitable material for this application. In particular, because of its low adhesion features, an air gap of around 150 µm is naturally formed during fabrication in between the two copper/tin coated textile electrodes. This air gap adds a second dielectric layer to our sensor and triggers very high performances at very low pressures (ca. 0-2 kPa). The woven fabric used in this work presents two main perpendicular sets of conductive yarns (i.e. warp and weft) where the warp yarn is interlaced up and down of the weft yarn creating an opening called shed (see S1, Supporting Information). The volume of air created by the shed contributes to the formation of a third dielectric layer which plays an important role at higher pressures (>2 kPa). This unique composite structure is embedded in between two polydimethylsiloxane (PDMS) packaging layers to form a mechanically fl exible and robust capacitive sensor ). The sensor design has four square The emulation of natural touch requires tactile sensors that mechanically comply with the environment -in order to gain relevant information from physical interactions -and that, at the same time, are able to perform when smoothly adapted to host three-dimensional structures. For this purpose, successive solutions have been attempted. However, to shape deformable materials while developing high precision, yet robust, systems is complex, and it reveals interesting scientifi c questions in addition to technological challenges. As a result, fl exible tactile sensors can present a very high pressure sensitivity, but the low saturation level (less than 50 kPa), intrinsically imposed by their architecture and/or manufacturing technology, limits their applications. Moreover, one fundamental function is still being overlooked, and that is the detection of contact force not only in the normal direction to the sensor/object interface, but also in the tangential direction. This would raise the level of encoded information by an artifi cial touch system closer to natural touch, for instance, slippage and texture detection. However, in comparison to pressure sensitive devices, or combined pressure and strain sensors, only a small number of skin-like sensors that can sense normal and tangential forces has been presented in the literature. In this context, stateof-the-art developments expose two main challenges: on the one hand, highly sensitive and fl exible devices able to detect forces in three dimensions over a large force range are pursued; whereas on the other hand, which is more economically related, their fabrication on large areas is requested. Original alternative sensor designs, using soft materials and processes have been shown to skirt those aspects and/or simplify fabrication processes. Among these, capacitive-based sensors show good potential towards deformable tactile sensors. In particular, Surapaneni et al. have demonstrated very high force range detection (up 320 kPa) and minimum detectable displacement of 60 µm using gold fl oating electrodes in comb-like structures, whereas other groups, in particular, Noda et al. have introduced original approaches for three-axis force detection [+] These authors contributed equally to this work. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
In drug therapy, most therapeutic drugs are of low molecular weight and could freely diffuse in t... more In drug therapy, most therapeutic drugs are of low molecular weight and could freely diffuse in the biological milieu depending on the administration route applied. The main reason for the development of polymeric drug carriers is to obtain desired effects such as sustained therapy, local and controlled release, prolonged activity and reduction of side effects. Alternatively, polymeric carriers can be made bioerodible in order to be eliminated by natural ways after a certain time of therapy. Core-shell fibres from coaxial spinneret or emulsion electrospinning are good candidates for the development of such devices; however difficulties remain especially in controlling the release over a sustained period. Here, we present a novel technique combining coaxial and emulsion electrospinning to produce microstructured core-shell fibres. The design of drug microreservoirs of variable size within the bulk of the fibre combined with a tailored diffusive barrier allows modulating the release kinetics of these novel carriers. A nearly constant and linear release of the model drug Levetiracetam (M w z 170 g mol À1 ) from PLGA emulsion-coaxial electrospun fibres is observed over 20 days. This device is aimed to be implanted into the brain for the treatment of epilepsy and is an example of the new capabilities and the promising potential that emulsion-coaxial electrospinning can provide towards the development of future drug carriers.
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Papers by Lucie Viry