Impedimetric Microfluidic Sensor-in-a-Tube for Label-Free Immune Cell Analysis

Analytical platforms based on impedance spectroscopy are promising for non-invasive and label-free analysis of single cells as well as of their extracellular matrix, being essential to understand cell function in the presence of certain diseases. Here, an innovative rolled-up impedimetric microfulidic sensor, called sensor-in-a-tube, is introduced for the simultaneous analysis of single human monocytes CD14+ and their extracellular medium upon liposaccharides (LPS)-mediated activation. In particular, rolled-up platinum microelectrodes are integrated within for the static and dynamic (in-flow) detection of cells and their surrounding medium (containing expressed cytokines) over an excitation frequency range from 102 to 5 × 106 Hz. The correspondence between cell activation stages and the electrical properties of the cell surrounding medium have been detected by electrical impedance spectroscopy in dynamic mode without employing electrode surface functionalization or labeling. The designed sensor-in-a-tube platform is shown as a sensitive and reliable tool for precise single cell analysis toward immune-deficient diseases diagnosis

Electronically integrated microcatheters based on self-assembling polymer films

Existing electronically integrated catheters rely on the manual assembly of separate components to integrate sensing and actuation capabilities. This strongly impedes their miniaturization and further integration. Here, we report an electronically integrated self-assembled microcatheter. Electronic components for sensing and actuation are embedded into the catheter wall through the self-assembly of photolithographically processed polymer thin films. With a diameter of only about 0.1 mm, the catheter integrates actuated digits for manipulation and a magnetic sensor for navigation and is capable of targeted delivery of liquids. Fundamental functionalities are demonstrated and evaluated with artificial model environments and ex vivo tissue. Using the integrated magnetic sensor, we develop a strategy for the magnetic tracking of medical tools that facilitates basic navigation with a high resolution below 0.1 mm. These highly flexible and microsized integrated catheters might expand the boundary of minimally invasive surgery and lead to new biomedical applications. Copyright © 2021 The Authors, some rights reserved

Ingénierie des contraintes de films minces de polymères : une nouvelle voie pour le développement de matériaux fonctionnels et d'outils microfluidiques

Les deux systèmes de création d’une contrainte dans les films polymériques ont été développés, chacun répondant à un gradient de gonflement du polymère dans la direction normale au film. Ce gonflement peut être provoqué soit par la présence d’un gradient de densité de réticulation dans la direction normale à la surface (films de poly(4-vinylpyridine) réticulés par UV ou dans les films de chitosan réticulés thermiquement et ioniquement ; ou soit par une pénétration asymétrique de vapeur de solvant dans le film (ici le polydiméthylsiloxane oxydé en surface). Un troisième système polymérique auto-enroulant a également été réalisé par la création d’une contrainte permanente au sein du film de polydiméthylsiloxane, grâce à l’extraction sélective d’un additif non-réticulé, l’huile de silicone. Un modèle théorique du processus d’auto-enroulement, basé sur la théorie linéaire d’élasticité a ainsi pu être proposé.Two systems of stress creation in the polymer films were developed, each based on the swelling gradient in the direction normal to the film. This swelling may be caused either by the presence of a crosslinking density gradient in the direction normal to the surface (poly (4-vinylpyridine film) crosslinked by UV or in the thermally or ionically crosslinked chitosan films; or by asymmetric penetration of solvent vapor in the film (here polydimethylsiloxane surface-oxidized). A third self-rolling polymeric system has also been realized by the creation of a permanent strain in the polydimethylsiloxane film by selective extraction of a non-cross-linked additive, silicone oil. A theoretical model of self-rolling process based on the linear theory of elasticity has been proposed

Carbon-Iron Microfibrous Material Produced by Thermal Treatment of Self-rolled Poly(4-vinyl pyridine) Films Loaded by Fe2O3 Particles

International audienceEnsembles of freeze-dried self-rolled polymer micro-scrolls are explored as template media for producing carbon-iron based composites with fibrous morphology. Polymer fibres impregnated with furfuryl alcohol and loaded with Fe2O3 particles, were thermally treated under inert atmosphere at 700 °C and subsequently analysed by scanning and transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, and nitrogen adsorption. The resulting material has a micro-fibrous morphology and is basically composed of metallic Fe0 and FeO particles, i.e., more than 98 wt% of the carbon/iron-based composite mass. These particles are held together by amorphous porous carbon foam obtained by in-situ carbonization of the polymer/Fe2O3 composite with evacuation of carbon from the system via COx gases released by carbo-reduction of Fe2O3. The material has significant activity in the reaction of catalytic decomposition of hydrogen peroxide in water solutions

Self-assembled sensor-in-a-tube as a versatile tool for label-free EIS viability investigation of cervical cancer cells

The advancement of micro and nanotechnology has led to the manufacturing of miniaturized sensors with improved functionalities for highly sensitive point of care devices. This work is particularly focused on analysing cancer cells and the effect of a model drug on their survival rate. To that end, we developed a highly sensitive rolled-up micro-electrochemical impedance spectroscopy sensor, encapsulated into a microfluidic channel. The sensor was built by strain engineering of shapeable materials and with diameters close to the cell size to improve their sensitivity. To demonstrate the platform performance, we first carried out measurements with different electrode geometries using cell medium at different concentrations. We also performed measurements using cancer cell suspensions, obtaining distinct signals from single cells, cell clusters and cellular debris. Finally, cancer cells were treated with an anticancer drug (Camptothecin), at different concentrations, over the same period, and further analysed using the developed platform

Carbon microtubes derived from self-rolled chitosan acetate films and graphitized by joule heating

International audienceHerein, a fast and efficient approach is proposed to obtain carbon microtubes with graphitic structure. The precursor tubes are formed via self-rolling of chitosan acetate (CA) biopolymer films in water. The self-rolling capacity is imparted to the CA films by heating them at 150 °C on a hot plate for several minutes in the ambient atmosphere. The resulting differential swelling of the top and bottom layers of the films in water generates the bending moment. The amorphous carbon microtubes are produced in Ar atmosphere via thermal treatment of chitosan acetate microtubes at 900 °C. Carbon/oxygen ratio increases from 1.2 for the pristine chitosan tube to 5.3 after the pyrolysis process. Finite electrical conductivity of the so-prepared tubes (σ ≈ 1 · 103 S · m−1) allows their consecutive treatment by joule heating. The current-induced graphitization of the tubes at 2500 °C is confirmed by TEM, Raman spectroscopy and XRD techniques. Electrical conductivity of tubes raised in course of the treatment to (σ ≈ 1.8 · 104 S · m−1). In joule-heated tubes, the carbon/oxygen ratio increases to 9.4

Lab-In-A-Tube: From Molecule to Cell Detection

The intriguing properties of self-assembled microtubular architectures open new possibilities to develop three-dimensional functional devices for molecule and cell analysis. [...