Conducting polymer tattoo electrodes in clinical electro- and magneto-encephalography

Abstract Temporary tattoo electrodes are the most recent development in the field of cutaneous sensors. They have successfully demonstrated their performances in the monitoring of various electrophysiological signals on the skin. These epidermal electronic devices offer a conformal and imperceptible contact with the wearer while enabling good quality recordings over time. Evaluations of brain activity in clinical practice face multiple limitations, where such electrodes can provide realistic technological solutions and increase diagnostics efficiency. Here we present the performance of inkjet-printed conducting polymer tattoo electrodes in clinical electroencephalography and their compatibility with magnetoencephalography. The working mechanism of these dry sensors is investigated through the modeling of the skin/electrode impedance for better understanding of the biosignals transduction at this interface. Furthermore, a custom-made skin phantom platform demonstrates the feasibility of high-density recordings, which are essential in localizing neuropathological activities. These evaluations provide valuable input for the successful application of these ultrathin electronic tattoos sensors in multimodal brain monitoring and diagnosis

Procédés lithographiques pour les technologies des semi-conducteurs inférieures à 90 nm : de la synthèse à l'étude des mécanismes physicochimiques induisant la rugosité des motifs

L'augmentation de la performance des circuits intégrés est assurée aujourd hui par la diminution constante de leurs dimensions. En 2001 l'ITRS introduit la rugosité de ligne des motifs "Line Edge Roughness" liée à la miniaturisation des produits de nouvelNowadays, the increasing performance of the integrated circuits is produced by the constant reduction of their dimensions. The "International Technology Roadmap for Semiconductors" is introduced in 2001 the "Line Edge Roughness" parameter depending on th

Procédés lithographiques pour les technologies des semi-conducteurs inférieures à 90nm (De la synthèse à l étude des mécanismes physicochimiques induisant la rugosité des motifs)

L augmentation de la performance des circuits intégrés est assurée aujourd hui par la diminution constante de leurs dimensions. En 2001 l ITRS introduit la rugosité de ligne des motifs "Line Edge Roughness" liée à la miniaturisation des produits de nouvelle génération dans l industrie microélectronique. Cette rugosité des motifs des résines photosensibles apparait pendant le procédé microlithographique et sera transférée dans les transistors fabriqués en diminuant leur performance. L objet de ce travail est de comprendre les mécanismes physico-chimiques induisant à la rugosité des motifs et optimiser la synthèse ainsi que la formulation des résines photosensibles pour diminuer la valeur de ce nouveau facteur. Pour identifier et dévoiler les mécanismes physico-chimiques influençant le LER, nous avons étudié d une part les résines positives commerciales et d autre part, nous avons synthétisé de nouveaux polymères de différentes compositions chimiques, masses moléculaires, polymolécularités et architectures. Nous avons utilisé ces polymères pour la formulation des résines photosensibles modèles et déterminé les valeurs de LER de ces dernières. D après nos études nous avons montré l effet de la masse moléculaire et de l indice de polymolécularité sur la performance lithographique. Les polymères linaires modèles à faible masse moléculaire ou à polymolécularité intermédiaire montrent une rugosité des motifs similaire à celle des résines commerciales. Enfin, nous avons proposé une nouvelle approche qui doit permettre de diminuer la rugosité de motifs utilisant des architectures macromoléculaires branchées et photoclivables. Celles-ci présentent une sensibilité lithographique et la capacité d imprimer les motifs de 100nm.Nowadays, the increasing performance of the integrated circuits is produced by the constant reduction of their dimensions. The "International Technology Roadmap for Semiconductors" is introduced in 2001 the "Line Edge Roughness" parameter depending on the miniaturization of the next generations components in the microelectronic industry. This patterns roughness appeared in microlithographic processes using a photosensitive resist and subsequent by transferring to the manufacturing of the transistor, their performance is decreasing. The objective of this work is to study the physical chemical mechanisms, inducing the LER, and optimize the synthesis and formulation of the photosensitive resists in order to reach acceptable values for this new parameter. In order to identify and unveil the impact of the physical chemical mechanisms on the LER, we studied in parallel, commercial positive resists, and at the same time we synthesized new polymers, having various chemical compositions, molecular weights, polydispersity indexes and polymer architectures. We have used them to formulate model photosensitive resists and defined the values of LER. According to our work, we identified the impact of the polymer molecular weight and the polydispersity on the lithographic performances. The low molecular weight and intermediate polydispersity of linear polymers showed a similar LER compared to the commercial photoresists. Finally, we have proposed a new approach to reduce the roughness of the patterns by using hyperbranched and photocleavables macromolecular architectures showing a good lithographic sensitivity and capability to 100 nm patterning.STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF

Special Issue on \u201cElectronic Textiles\u201d

This special issue on electronic textiles was planned together with Wiley and the European Materials Research Society (E\u2010MRS) by the organizers of Symposium J \u201cElectronic textiles\u201d at the E\u2010MRS Spring 2017 meeting in Strasbourg, France. Advanced Materials Technologies is new to the Advanced Materials series at Wiley and focuses specifically on \u201cadvanced device design, fabrication and integration, as well as new technologies based on novel materials\u201d. We thus see the journal as an ideal venue for this special issue on this emerging field

Interdigitated Organic Sensor in Multimodal Facemask’s Barrier Integrity and Wearer’s Respiration Monitoring

Facemasks are used as a personal protective equipment in medical services. They became compulsory during the recent COVID-19 pandemic at large. Their barrier effectiveness during various daily activities over time has been the subject of much debate. We propose the fabrication of an organic sensor to monitor the integrity of surgical masks to ensure individuals’ health and safety during their use. Inkjet printing of an interdigitated conducting polymer-based sensor on the inner layer of the mask proved to be an efficient and direct fabrication process to rapidly reach the end user. The sensor’s integration happens without hampering the mask functionality and preserving its original air permeability. Its resistive response to humidity accumulation allows it to monitor the mask’s wetting in use, providing a quantified way to track its barrier integrity and assist in its management. Additionally, it detects the user’s respiration rate as a capacitive response to the exhaled humidity, essential in identifying breathing difficulties or a sign of an infection. Respiration evaluations during daily activities show outstanding performance in relation to unspecific motion artifacts and breathing resolution. This e-mask yields an integrated solution for home-based individual monitoring and an advanced protective equipment for healthcare professionals

Capacitive Coupling of Conducting Polymer Tattoo Electrodes with the Skin

International audienceTattoo electronics is one of the emerging technologies in skin compliant biosensing. The growing interest in their large application in health monitoring raises several interrogations on how these sensors interface with the skin. In this paper, the bioimpedance at the interface of the skin and ultra-conformable tattoo electrodes made of conducting polymers are focused on. The electrochemical characteristics of these electrodes differ from traditional gelled Ag/AgCl electrodes. The modeling of equivalent circuits in different skin-electrode configurations proposes the explanation of the biopotentials transduction mechanism. The strong agreement between the circuit model and experimental values reveals the capacitive coupling of conducting polymer tattoo electrodes where circuit's values reflect the electrodes’ and skin physical characteristics. Additional studies underline an enhanced signal stability in inter/intra-subject evaluations using dry tattoos beneficial for broad long-term recordings. This study provides a comprehensive explanation of the skin/tattoo electrode interface model. The understanding of this interface is essential when designing next generation wearable biomonitoring devices using imperceptible interfaces

Kinetics and Physicochemical Characteristics of Electrodeposited PEDOT:PSS Thin Film Growth

Abstract In bioelectronics, conducting polymer coatings allow the reduction of the impedance of metallic electrodes and facilitate the translation of bioelectrical signals at their interface. Such coatings can be made using thin film deposition from a solution or direct synthesis via electrodeposition. The electrical control over the deposition offers the possibility for a fine‐tuning of the film's thickness and structure. However, the mechanical stability of such coatings mainly suffer from their poor adhesion to the electrode surface and film cracking. Here, an extended study on the kinetics of poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) electropolymerization and the evolution of its physicochemical properties is provided. The impedance spectroscopy closely follows the electrochemical variations during the PEDOT:PSS's film growth, described by modeled equivalent circuits. The film's properties change during polymerization in relation to the supporting electrode size, its surface chemistry, and the deposition time. The film growth structures polymeric morphology in a confluent layer with a strong thickness increase before reaching its mechanical surface failure. Before this point, the film remains stable over a hundred cycles of applied potential strain in a defined redox window. These evaluations benchmark the PEDOT:PSS film properties during its electropolymerization toward electrochemically tunable transducers for bioelectronics

Mechanistic study of Atom Transfer Radical Polymerization in the Presence of an Inimer: Toward Highly Branched Controlled Macromolecular Architectures through One-Pot Reaction

Highly branched polymethacrylates have recently offered new perspectives in lithographic performance and drug delivery. The control of branching remains yet challenging and requires fundamental investigation to consider new applications. Therefore, an advanced study of the formation mechanism of branched polymers synthesized by self-condensing vinyl copolymerization (SCVCP) of a methacrylic AB* inimer, 2-(2-bromoisobutyryloxy)ethyl methacrylate (BIEM), with methyl methacrylate (MMA) via atom transfer radical polymerization (ATRP) has been performed. Evidence of branched structures was obtained with a conventional GPC apparatus equipped with a multiangle light scattering detector and detailed (1)H NMR analyses. A three-step reaction scheme is suggested according to the dependence of molecular weight with conversion. Controlled radical polymerization mainly occurs until moderate conversions, with the participation of inimer as chain initiator. Then the polymerization of small macromolecules, through consumption of polymerizable moiety, dramatically increases the molecular weight of polymer. Finally, a loss of control partially due to thermal decomposition of residual comonomers occurs at high conversion. This mechanistic methodology will allow, with adequate reaction process, the one-step preparation of controlled branched macromolecular architectures leading to functional materials

One-class autoencoder approach for optimal electrode set-up identification in wearable EEG event monitoring

International audienceA limiting factor towards the wide real-life use of wearables devices for continuous healthcare monitoring is their cumbersome and obtrusive nature. This is particularly true for electroencephalography (EEG) recordings, which require the placement of multiple electrodes in contact with the scalp. In this work we propose to identify the optimal wearable EEG electrode setup , in terms of minimal number of electrodes, comfortable location and performance, for EEG-based event detection and monitoring. By relying on the demonstrated power of autoencoder (AE) networks to learn latent representations from high-dimensional data, our proposed strategy trains an AE architecture in a one-class classification setup with different electrode setups as input data. The model performance is assessed using the F-score. Alpha waves detection is the use case, through which we demonstrate that the proposed method allows to detect an alpha state from an optimal setup. The socalled wearable configuration, consisting of electrodes in the forehead and behind the ear, is the chosen optimal setup , with an average F-score of 0.78. Our results suggest that a learning-based approach can be used to enable the design and implementation of optimized wearable devices for real-life event related healthcare monitoring

Cutaneous Recording and Stimulation of Muscles Using Organic Electronic Textiles

International audienceElectronic textiles are an emerging field providing novel and non-intrusive solutions for healthcare. Conducting polymer-coated textiles enable a new generation of fully organic surface electrodes for electrophysiological evaluations. Textile electrodes are able to assess high quality muscular monitoring and to perform transcutaneous electrical stimulation