Combinatiorial method for surface-confined sensor desing and fabrication

The procedure for the combinatorial fabrication of new sensing materials for cations and anions based on self-assembled monolayers (SAM) is discussed. A library of different sensitive substrates is generated by sequential deposition of fluorophores and small ligand molecules onto an amino-terminated SAM coated glass. The preorganization provided by the surface avoids the need for complex receptor design, allowing for a combinatorial approach to sensing systems based on individually deposited small molecules. Additionally the sensing system has been miniaturized to the microscale using microcontact printing and integrating the sensory SAMs on the walls of microchannels

Liquid recirculation in microfluidic channels by the interplay of capillary and centrifugal forces

We demonstrate a technique to recirculate liquids in a microfluidic device, maintaining a thin fluid layer such that typical diffusion times for analytes to reach the device surface are < 1 min. Fluids can be recirculated at least 1000 times across the same surface region, with no change other than slight evaporation, by alternating the predominance of centrifugal and capillary forces. Mounted on a rotational platform, the device consists of two hydrophilic layers separated by a thin pressure-sensitive adhesive (PSA) layer that defines the microfluidic structure. We demonstrate rapid, effective fluid mixing with this device

Cross-Reactive Sensor Array for Metal Ion Sensing Based on Fluorescent SAMs\ud

Fluorescent self assembled monolayers (SAMs) on glass were previouslydeveloped in our group as new sensing materials for metal ions. These fluorescent SAMs arecomprised by fluorophores and small molecules sequentially deposited on a monolayer onglass. The preorganization provided by the surface avoids the need for complex receptordesign, allowing for a combinatorial approach to sensing systems based on small molecules.Now we show the fabrication of an effective microarray for the screening of metal ions andthe properties of the sensing SAMs. A collection of fluorescent sensing SAMs wasgenerated by combinatorial methods and immobilized on the glass surfaces of a custom-made 140 well microtiter-plate. The resulting libraries are easily measured and show variedresponses to a series cations such as Cu2+ , Co2+ , Pb2+ , Ca2+ and Zn2+ . These surfaces are notdesigned to complex selectively a unique analyte but rather they are intended to producefingerprint type responses to a range of analytes by less specific interactions. The unselectiveresponses of the library to the presence of different cations generate a characteristic patternfor each analyte, a “finger print” response.\u

Yersinia enterocolitica prevalence and diversity in a pig slaughterhouse

Yersinia enterocolitica is involved in human foodborne infections. Pigs are considered as a major reservoir in many countries. The aim of the study was to contribute to the evaluation of the prevalence of Y. enterocolitica in France in pigs at the slaughterhouse level with optimized detection methods based on ISO 10273-2003

Tunable Superparamagnetic Ring (tSPRing) for Droplet Manipulation

The manipulation of droplets by magnetic field forms the basis of a fascinating technology that is currently in development. Often, the movement of droplets with magnets involves adding magnetic particles in or around the droplet; alternatively, magneto responsive surfaces may also be used. This work, presents and characterizes experimentally the formation and properties of a tunable superparamagnetic ring (tSPRing), which precisely adjusts itself around a water droplet, due to liquid-liquid interaction, and enables the physical manipulation of droplets. The ring is made of an oil-based ferrofluid, a stable suspension of ferromagnetic particles in an oily phase. It appears spontaneously due to the oil-water interfacial interaction under the influence of a magnetic field. The ferrofluid-water interaction resembles a cupcake assembly, with the surrounding ring only at the base of the droplet. The ring is analogous to a soft matter ring magnet, showing dipole repulsive forces, which stabilizes the droplets on a surface. It enables robust, controllable and programmable manipulation of enclosed water droplets. This work opens the door to new applications in open surface upside or upside-down microfluidics and lays the groundwork for new studies on tunable interfaces between two immiscible liquids.Authors acknowledge funding support from MaMi project, funded by the European Union's Horizon 2020 research and innovation programme under grant agreement No. 766007, from the Basque Government, under Grupos Consolidados with Grant No. IT1271-19 and from Gobierno de España, Ministerio de Economia y Competitividad, with Grant No. BIO2016-80417-P (AEI/FEDER, UE

From image to technology: a multidisciplinary approach for improving the quality of organic bread.

This study is part of a research programme devoted to improving the quality of organic bread. It aims to identify and test prototypes of breads approved by consumers. This is achieved by analysing consumer representations and preferences and placing them within the framework of technological, sensory and nutritional dimensions of the products. The multidisciplinary approach implements an original qualitative approach that combines three consumer focus groups made up of both loyal and occasional consumers, and confrontation sessions with the programme scientific partners. Four prototypes of organic breads have thus been formalised and subsequently tested on a sample of 120 consumers from two sites (Angers and Strasbourg). From an operational point of view, proposals for organic breads approved by consumers are formulated. In terms of methodology, the contributions of a multidisciplinary study are discussed

Thin film diffusion barrier formation in PDMS microcavities

We describe a method to form glass like thin film barrier in polydimethylsiloxane (PDMS) microcavities. The reactive fragments for the surface reaction were created from O2 and hexamethyldisiloxane (HMDS) in RF plasma environment. The reaction is based on migration of the reactive fragments into the microcavities by diffusion, to form a glass like thin film barrier to conceal the naked surface of PDMS. The barrier successfully blocked penetration of a fluorescent dye rhodamine B (RhB) into PDMS. The thickness of the barrier could be controlled by the time of reaction and the pressure inside the reaction chamber. There is a wide range of applications of such a technique in various fields, e.g. for coating the covered surfaces of microfluidic channels, tubes, capillaries, medical devices, catheters, as well as chip-integrated capillary electrophoresis and advanced electronic and opto-fluidic packaging

Advances in Microtechnology for Improved Cytotoxicity Assessment

In vitro cytotoxicity testing is essential in the pharmaceutical and environmental industry to study the effects of potential harmful compounds for human health. Classical assays present several disadvantages: they are commonly based on live-death labelling, are highly time consuming and/or require skilled personnel to be performed. The current trend is to reduce the number of required cells and the time during the analysis, while increasing the screening capability and the accuracy and sensitivity of the assays, aiming single cell resolution. Microfabrication and surface engineering are enabling novel approaches for cytotoxicity assessment, offering high sensitivity and the possibility of automation in order to minimize user intervention. This review aims to overview the different microtechnology approaches available in this field, focusing on the novel developments for high-throughput, dynamic and real time screening of cytotoxic compounds.Funding support from: University of the Basque Country (PIF16/204), the funding support from Gobierno de España, Ministerio de Economía y Competitividad, with Grant No. BIO2016-80417-P (AEI/FEDER, UE) and Gobierno Vasco under grand IT1271-19

Low‑cost origami fabrication of 3D self‑aligned hybrid microfluidic structures

[EN] 3D microfluidic device fabrication methods are normally quite expensive and tedious. In this paper, we present an easy and cheap alternative wherein thin cyclic olefin polymer (COP) sheets and pressure sensitive adhesive(PSA) were used to fabricate hybrid 3D microfluidic structures, by the Origami technique, which enables the fabrication of microfluidic devices without the need of any alignment tool. The COP and PSA layers were both cut simultaneously using a portable, low-cost plotter allowing for rapid prototyping of a large variety of designs in a single production step. The devices were then manually assembled using the Origami technique by simply combining COP and PSA layers and mild pressure. This fast fabrication method was applied, as proof of concept, to the generation of a micromixer with a 3D-stepped serpentine design made of ten layers in less than 8 min. Moreover, the micromixer was characterized as a function of its pressure failure, achieving pressures of up to 1000 mbar. This fabrication method is readily accessible across a large range of potential end users, such as educational agencies (schools,universities), low-income/developing world research and industry or any laboratory without access to clean room facilities, enabling the fabrication of robust, reproducible microfluidic devices.Fernando Benito-Lopez acknowledges the Ramón y Cajal Programme (Ministerio de Economía y Competitividad), Spain. This project has received funding from the European Union´s Seventh Framework Programme (FP7) for Research, Technological Development and Demonstration under Grant agreement no. 604241. LBD personally acknowledges to Elkartek (KK-2015/00088) Grant form the Gobierno Vasco. JS and FBL personally acknowledge Marian Martínez de Pancorbo for let them use her laboratory facilities at UPV/EHU. Authors also acknowledge Adhesive Research for the donation of the PSA samples and to Iñaki Veci for the drawing of the 3D scheme