A resonant structure designed for probing the elastic properties of suspension and adherent cells in liquid environments

9 ppInternational audienceThis paper presents a novel force sensitive structure exploiting a dynamic mode for probing the elastic properties of living cells. A key feature of this structure is the possibility of conducting measurements in liquid environments while keeping high dynamic performances. The structure indeed provides a steady area that can be adapted so that suspension or adherent cells can be placed in a culture medium. The steady area is also connected to two adjacent beam resonators. Because these resonators never need to be immersed into the culture medium during measurements, forces applied to cells can be estimated with a high sensitivity via frequency shifts. In this paper, we conduct an extensive theoretical analysis to investigate the nonlinear effects of large static pre-deflections on the dynamic behavior of the structure. As a proof of concept, we also report the fabrication, characterization and calibration of the first prototype intended to deal with suspension cells with a diameter ranging from 100 to 500 μm. This prototype currently offers a quality factor of 700 and a force sensitivity of ∼2.6 HzmN−1. We also demonstrate that the prototype is capable of measuring the elastic modulus of biological samples in a rapid and sufficiently accurate manner without the need of a descriptive model

A plant-like battery : a biodegradable power source ecodesigned for precision agriculture

The natural environment has always been a source of inspiration for the research community. Nature has evolved over thousands of years to create the most complex living systems, with the ability to leverage inner and outside energetic interactions in the most efficient way. This work presents a flow battery profoundly inspired by nature, which mimics the fluid transport in plants to generate electric power. The battery was ecodesigned to meet a life cycle for precision agriculture (PA) applications; from raw material selection to disposability considerations, the battery is conceived to minimize its environmental impact while meeting PA power requirements. The paper-based fluidic system relies on evaporation as the main pumping force to pull the reactants through a pair of porous carbon electrodes where the electrochemical reaction takes place. This naturally occurring transpiration effect enables to significantly expand the operational lifespan of the battery, overcoming the time-limitation of current capillary-based power sources. Most relevant parameters affecting the battery performance, such as evaporation flow and redox species degradation, are thoroughly studied to carry out device optimization. Flow rates and power outputs comparable to those of capillary-based power sources are achieved. The prototype practicality has been demonstrated by powering a wireless plant-caring device. Standardized biodegradability and phytotoxicity assessments show that the battery is harmless to the environment at the end of its operational lifetime. Placing sustainability as the main driver leads to the generation of a disruptive battery concept that aims to address societal needs within the planetary environmental boundaries. A biodegradable battery inspired by the transpiration pull of liquids in plants has been ecodesigned to power wireless sensors and then be safely biodegraded or composted, resembling the way a plant comes back to nature at the end of its lifecycle

Conception d'une structure résonante pour la caractérisation mécanique cellulaire

In the future, credit-card sized and self-contained platforms that will be capable of measuring the Young's modulus of various types of cells in a high throughput manner could mark a new milestone in medicine and biomedical research. Indeed, the Young's modulus of cells appears today as a new meaningful marker for detecting several cell-based degenerative diseases at earlier stages. Besides, Young's modulus measurements may have the potential to disclose the specific effects of pharmaceuticals at the cellular level. Hence, measuring the Young's modulus of cells might also prove advantageous in drug development. However, exploiting the Young's modulus of cells as a reliable indicator still poses challenges. This doctoral dissertation reports the design, modeling and experimental validation of a novel force sensor aimed at bringing new solutions to problems encountered so far. Unlike most force sensitive systems intended to extract the Young's modulus of living cells, the force sensor presented in this work is based on a planar structure that exploits a resonant mode for achieving higher force sensitivity. In particular, the structure has been devised to maintain high dynamic performances even if cells are cultured in growth medium. Another key feature of the structure is that it has the potential to address both suspension and adherent cells. In addition, results reported in this work confirm that it can be used to rapidly estimate the Young's modulus of living cells without the need of a descriptive model and a microscope.Dans l'avenir, le développement de nouvelles plateformes autonomes et portatives capables de mesurer rapidement le module de Young de cellules biologiques pourraient révolutionner la recherche biomédicale. Le module de Young se révèle en effet aujourd'hui être un indicateur de plus en plus pertinent pour la détection précoce de diverses maladies dégénératives cellulaires. La mesure du module de Young à l'échelle cellulaire peut de plus permettre d'apprécier l'action de principes actifs pour le développement de nouveaux traitements médicamenteux ciblés. Cependant, la valeur du module de Young ne peut encore à l'heure actuelle être utilisée comme un indicateur fiable. Cette thèse présente la conception, la modélisation et la validation expérimentale d'un nouveau capteur de force visant à pallier certaines limitations actuellement rencontrées. Contrairement à la plupart des dispositifs développés jusqu'à présent, le capteur de force présenté dans cette thèse consiste en une structure planaire résonante offrant un coefficient de qualité élevé. La structure a été pensée non seulement pour conserver des performances élevées même en présence de liquide, mais également pour caractériser différents types de cellules (cellules en suspension ou cellules adhérentes). De plus, les résultats obtenus dans le cadre de cette thèse démontrent que la structure proposée permet d'estimer rapidement le module de Young de cellules sans avoir nécessairement recours à un modèle analytique ou à un microscope

Fabrication of a new Glucose/O2 microfluidic biofuel cell using thin and flexible films

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Microfluidic enzymatic biofuel cells to generate electrical energy

International audienc

Actuation means for the mechanical stimulation of living cells via microelectromechanical systems: A critical review

International audienceWithin a living body, cells are constantly exposed to various mechanical constraints. As a matter of fact, these mechanical factors play a vital role in the regulation of the cell state. It is widely recognized that cells can sense, react and adapt themselves to mechanical stimulation. However, investigations aimed at studying cell mechanics directly in vivo remain elusive. An alternative solution is to study cell mechanics via in vitro experiments. Nevertheless, this requires implementing means to mimic the stresses that cells naturally undergo in their physiological environment. In this paper, we survey various microelectromechanical systems (MEMS) dedicated to the mechanical stimulation of living cells. In particular , we focus on their actuation means as well as their inherent capabilities to stimulate a given amount of cells. Thereby, we report actuation means dependent upon the fact they can provide stimulation to a single cell, target a maximum of a hundred cells, or deal with thousands of cells. Intrinsic performances, strengths and limitations are summarized for each type of actuator. We also discuss recent achievements as well as future challenges of cell mechanostimulation

Microfluidic enzymatic biofuel cells to generate electrical energy

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Design and Fabrication of a Novel Resonant Surface Sensitive to Out-of-plane Forces for the Indentation and Injection of Living Cells

Abstract — We present a novel force sensor for cell indentation and cell injection. This force sensor is a monolithic structure that integrates two resonators. It provides a surface sensitive to out-of-plane forces where a living cell can be conveniently placed for manipulation. Normal forces applied upon the cell under study are estimated via frequency shifts of the resonators. In this paper, we develop a theoretical study for predicting and optimizing the structure’s sensitivity. As a proof of concept, we also report the fabrication and experimental characterization of a first prototype. In ambient conditions, our prototype presently offers a quality factor of ∼700, and a linear sensitivity of ∼5.75 Hz /µm. In addition, we report the implementation of a compact and low-cost optical fiber setup to monitor the resonators ’ frequency. Potential applications are illustrated with the measurement of forces applied on lobster eggs. I

Including Liquid Metal into Porous Elastomeric Films for Flexible and Enzyme-Free Glucose Fuel Cells: A Preliminary Evaluation

This communication introduces a new flexible elastomeric composite film, which can directly convert the chemical energy of glucose into electricity. The fabrication process is simple, and no specific equipment is required. Notably, the liquid metal Galinstan is exploited with a two-fold objective: (i) Galinstan particles are mixed with polydimethylsiloxane to obtain a highly conductive porous thick film scaffold; (ii) the presence of Galinstan in the composite film enables the direct growth of highly catalytic gold structures. As a first proof of concept, we demonstrate that when immersed in a 20 mM glucose solution, a 5 mm-long, 5 mm-wide and 2 mm-thick sample can generate a volumetric power density up to 3.6 mW·cm − 3 at 7 mA·cm − 3 and 0.51 V without using any enzymes