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Electrochemical impedance spectroscopy (EIS) is widely accepted as an effective and non-destructive method to assess cell health during cell-culture. However, there is a lack of compact devices compatible with microfluidic integration and microscopy that could provide the real-time and non-invasive monitoring of cell-cultures using EIS. In this paper, we reported the design and characterization of a modular EIS testing system based on a patented technology. This device was fabricated using easily processable methodologies including screen-printing of the impedance electrodes and molding or micromachining of the cell culture chamber with an easy assembly procedure. Accordingly, to obtain processable, biocompatible and sterilizable electrode materials that lower the impact of interfacial impedance on TEER (Transepithelial electrical resistance) measurements, and to enable concomitant microscopy observations, we optimized the formulation of the electrode inks and the design of the EIS electrodes, respectively. First, electrode materials were based on carbon biocompatible inks enriched with IrOx particles to obtain low interfacial impedance electrodes approaching the performances of classical non-biocompatible Ag/AgCl second-species electrodes. Secondly, we proposed three original electrode designs, which were compared to classical disk electrodes that were optically compatible with microscopy. We assessed the impact of the electrode design on the response of the impedance sensor using COMSOL Multiphysics. Finally, the performance of the impedance spectroscopy devices was assessed in vitro using human airway epithelial cell cultures.

We have developed paper-based screen-printed biofuel cells using MgO-templated carbon (MgOC) as an electrode material1) in which a mediator and an enzyme were immobilized by dropping the solutions on the MgOC surface. However, the immobilization scheme should be shortened for practical applications. In this study, we newly prepare an enzyme-modified carbon ink using chitosan, which has high bio-affinity as a binder. By preparing chitosan-based enzyme ink, it becomes possible to immobilize the enzyme on the electrode by a simple printing process. A paper-based glucose/O2 biofuel cell was fabricated by screen printing with the enzyme-modified carbon inks. In this abstract, we describe the results of the glucose anode. Firstly, a glucose oxidase (GOx) and 1,2-naphthoquinone (1,2-NQ) were physically adsorbed in the pores of the MgOC. Then a chitosan-based enzyme ink was prepared by mixing the GOD and 1,2-NQ immobilized MgOCwith chitosan, and then cross-linked with genipin. A commercially available carbon ink and the as-prepared chitosan-based enzyme ink were successively printed on a water-repellent Japanese paper and dried overnight in a refrigerator to prepare a bioanode. In this study, we used two kinds of carbon. One is an untreated MgOC (normal MgOC). Another is a “washed MgOC”, which were washed with 0.25M NaOH and pure water before the chitosan-based enzyme ink was prepared. Anodes prepared with chitosan-based enzyme inks using normal MgOC and washed MgOC were evaluated by chronoamperometry (measurement potential: 0.2 V) in phosphate buffer containing 100 mM glucose (Fig.1 (a)). The catalytic oxidation reaction was not observed in the anode using normal MgOC, whereas the catalytic oxidation current of about 0.5 mA/cm2 was obtained after 500 seconds in the anode using the washed MgOC. From the SEM (accelerating voltage: 15.0 kV) of the anode using washed MgOC, a structure with many macroporesof about 5 to 10 µm was observed clearly. (Fig. 1(b)). On the other hand, no such macropores were observed in the anode using normal MgOC. The surface of normal MgOC has many functional groups such as -COOH, and it shows acidity when mixed with water. The cross-linking reaction does not occur sufficiently in between genipin and chitosan under acidic condition. On the other hand, in the neutral condiiton, the cross-linking reaction that accompanies the self-polymerization of genipin proceeds enough to form long and flexible chains 2). Therefore, the neutralization of the MgOC surface by the washing treatment forms an electrode with macropores between carbons, resulting in increase of glucose supply to the GOD immobilized in the mesopore of MgOC. References 1) Isao Shitanda et al., J. Electrochem. Soc, 166(12) (2019) B1063-B1068. 2) Elí Emanuel Esparza Floreset et al., Process Biochemistry, 84, (2019) 73-80. Acknowledgements This work was partially supported by JST-ASTEP Grant Number JPMJTS1513, JSPS Grant Number 17H02162 and Private University Research Branding Project (2017-2019) from Ministry of Education, Culture, Sports, Science and Technology, and Tokyo University of Science Grant for President's Research Promotion． Figure 1

The invention concerns a bioreactor obtained by compressing a mixture of an enzyme, a conductor and chitosan. The conductor can consist of carbon nanotubes. This bioreactor can be produced according to the following steps: preparing a mixture of powders in which the proportion of enzyme powder relative to a carbon nanotube powder is of the order of 50/50 by weight; preparing a viscous solution of chitosan in a ratio of 5 to 15 (in mg) of chitosan to 0.75 to 1.25 (in ml) of acetic acid diluted to 0.4 to 0.6% by volume in water; adding the viscous chitosan to the mixture of powders in a proportion be weight of 3 to 5 of powder to 5 to 10 of chitosan; carrying out a first compression followed by light grinding; carrying out a second compression to produce a pellet; and drying at ambient temperature., L'invention concerne un bioréacteur obtenu par compression d'un mélange d'une enzyme, d'un conducteur et de chitosane. Le conducteur peut être constitué de nanotubes de carbone. Ce bioréacteur peut être fabriqué selon les étapes suivantes : préparer un mélange de poudres dans laquelle la proportion de poudre d' enzyme par rapport à une poudre de nanotubes de carbone est de l'ordre de 50/50 en poids ; préparer une solution visqueuse de chitosane dans un rapport de 5 à 15 (en mg) de chitosane à 0,75 à 1,25 (en ml) d'acide acétique dilué à 0,4 à 0,6 % en volume dans de l'eau ; ajouter au mélange de poudres la chitosane visqueuse dans une proportion pondérale de 3 à 5 pour la poudre à 5 à 10 pour la chitosane ; procéder à une première compression puis à un broyage léger ; procéder à une deuxième compression pour réaliser une pastille ; et sécher à température ambiante.

International audience; Les polymères tels que le SU8 (biphénol A d'éther glycidyle), le PS233 (polysilane) et le matériau SOG (siloxane Spin On Glass) peuvent être utilisés conjointement dans la fabrication par processus couches minces de micro-résonateurs (MR) photoniques 2.5D. Cependant, ces matériaux n'étant pas toujours compatibles entre eux, il a été nécessaire d'inclure et d'optimiser des traitements plasmas au sein des processus couches minces de manière à augmenter l'adhérence et à permettre un développement sélectif de multicouches organiques en structures de type MR 2.5D disques et anneaux.

International audience; Thermally-assisted grafting of linear alkene molecules either in the liquid phase (ethyl undecylenate) or in the gas phase (perfluorodecene), has been performed on atomically flat amorphous carbon (a-C) films with variable average surface hybridization, sp3/(sp2 + sp3), as obtained from X-ray photoelectron spectroscopy. In contrast with the sp2-rich sputtered a-C, optimized sp3-rich a-C films obtained by Pulsed Laser ablation of a glassy carbon target do not require surface preparation before liquid phase grafting.