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tributylhexyl phosphonium sulfopropylacrylate (PSPA) poly(ionic liquid) (PILc) hydrogels as temperature controlled actuators in microfluidic devices. The hydrogel size is modulated by localised changes in its temperature due to the lower critical solution temperature (LCST) behaviour exhibited by PSPA.

The final publication is available at Springer via http://dx.doi.org/[10.1007/s10853-015-9458-2], [EN] This study focuses on improving the speed ofactuation of poly(N-isopropylacrylamide)-based photoresponsive gels containing copolymerised spiropyran as the photoswitch and acrylic acid as the proton source. The improvement is realised by introducing pores into the material. For this purpose, polyethylene glycol (PEG) of two molecular weights (2000 and 20000 g mol-1) has been used as the porophore in the polymerisation mixture. Upon removal of the PEG porophore post polymerisation, hydrogels of different pore sizes were obtained. This impacts the diffusion of water molecules moving in/out of the hydrogel matrix, thus improving the swelling and shrinking kinetics of the hydrogel due to reduction of the average diffusion pathlength. Most significant improvement was observed in the reswelling step and is demonstrated with optical microscopy combined with kinetic ultraviolet–visible spectroscopy (UV–Vis) analysis. Scanning electron microscopy reveals the PEG-induced pores to be in the range of 0.1–2 lm. Moreover, the mechanical stability of the gels is confirmed with rheometry. Lastly, the presented photoresponsive porous gels exhibit an order of magnitude faster reswelling rate compared to the non-PEG-produced control sample.

[EN] Herein we investigate the feasibility of detecting photo-induced surface stress changes using the deflection response of cantilevers. For this purpose, silicon microcantilevers have been functionalised with spiropyran photochromic molecules, using both a monolayer and a polymeric brushes approach. Uponultraviolet light irradiation, the spiropyran unit is converted to the merocyanine form due to the photo-induced cleavage of the Cspiro-O bond. The two forms of the molecule have dramatically different charge,polarity and molecular conformations. This makes spiropyrans an ideal system to study the correlation between photo-induced molecular changes and corresponding changes in surface stress. Our investigations include monitoring the changes in static cantilever deflection, and consequently, surface stress of the spiropyran functionalised cantilevers on exposure to ultraviolet light. Cantilever deflection data reveals that ultraviolet induced conformational changes in the spiropyran moiety cause a change incompressive surface stress and this varies with the type of functionalisation method implemented. The change in surface stress response from the spiropyran polymer brushes functionalised cantilevers gives an average surface stress change of 98 Nm−1(n = 24) while the spiropyran monolayer coated cantilevers have an average surface stress change of about 446 Nm−1(n = 8) upon irradiation with UV light.

Part of special issue: Proceedings of the 30th anniversary Eurosensors Conference – Eurosensors 2016, 4-7. Sepember 2016, Budapest, Hungary, The increment of uncontrolled nutrients concentration in water is the subject of increasing environmental concern. In particular, the increment of nitrate causes the eutrophication of algae, leading to fauna and flora demise. In order to favour an easy and adequate monitoring of this environmental problem, we have developed an ionogel-based sensor for the colorimetric determination and image analysis detection of nitrite and nitrate in water. The sensor consists on a small poly(methyl)methacrilate (PMMA) device cut by a CO2 laser where both the detection and the calibration zones are integrated. A simple photograph of the whole device, followed by colour processing of the different sections of the chip was used for the determination of nitrite concentrations.

Part of special issue: Proceedings of the 30th anniversary Eurosensors Conference – Eurosensors 2016, 4-7. Sepember 2016, Budapest, Hungary, Electrochemical Impedance Spectroscopy (EIS) studies of two different ionogels (IOs) are performed using gold interdigitated electrodes (Au-IDEs). Poly(N isopropylacrylamide) (pNIPAAM) is polymerized in the presence of two ionic liquids (ILs), ethyl- 3-methylimidazolium ethyl sulfate [C2mIm][EtSO2] (1) or trihexyltetradecyl-phosphonium dicyanamide [P6,6,6,14][DCA] (2). The Nyquist diagrams of the IOs reflect significant differences due to their polarity and porosity dissimilarities. This fact is supported with the study of the diffusion of water through the polymer matrix, which is faster for IO-1, the most porous IO. Moreover, the ability of IO-1 and IO-2 to conduct current is measured and the sheet resistance of IO-2 is two orders of magnitude higher than IO-1. Finally, the swelling/drying properties of the IOs are monitored exposing them to several vacuum and rehydration cycles. The Nyquist plot of IO-1 shows faster diffusion and recovery of the original properties. Both hydrophilicity and porosity are in the basis of these results.

[EN] Therefore the understanding and proper evaluation of the flow and mixing behaviour at microscale becomes a very important issue. In this study, the diffusion behaviour of two reacting solutions of HCI and NaOH were directly observed in a glass/polydimethylsiloxane microfluidic device using adaptive coatings based on the conductive polymer polyaniline that are covalently attached to the microchannel walls. The two liquid streams were combined at the junction of a Y-shaped microchannel, and allowed to diffuse into each other and react. The results showed excellent correlation between optical observation of the diffusion process and the numerical results. A numerical model which is based on finite volume method (FVM) discretisation of steady Navier-Stokes (fluid flow) equations and mass transport equations without reactions was used to calculate the flow variables at discrete points in the finite volume mesh element. The high correlation between theory and practical data indicates the potential of such coatings to monitor diffusion processes and mixing behaviour inside microfluidic channels in a dye free environment.

[EN] Parasitic diseases have a great impact in human and animal health. The gold standard for the diagnosis of the majority of parasitic infections is still conventional microscopy, which presents important limitations in terms of sensitivity and specificity and commonly requires highly trained technicians. More accurate molecular-based diagnostic tools are needed for the implementation of early detection, effective treatments and massive screenings with high-throughput capacities. In this respect, sensitive and affordable devices could greatly impact on sustainable control programmes which exist against parasitic diseases, especially in low income settings. Proteomics and nanotechnology approaches are valuable tools for sensing pathogens and host alteration signatures within micro fluidic detection platforms. These new devices might provide novel solutions to fight parasitic diseases. Newly described specific parasite derived products with immune-modulatory properties have been postulated as the best candidates for the early and accurate detection of parasitic infections as well as for the blockage of parasite development. This review provides the most recent methodological and technological advances with great potential for biosensing parasites in their hosts, showing the newest opportunities offered by modern “-omics” and platforms for parasite detection and control.

[EN] A new concept for fluid flow manipulation in microfluidic paper-based analytical devices (m-PADs) is presented by introducing ionogel materials as passive pumps. m-PADs were fabricated using a new doubleside contact stamping process and ionogels were precisely photopolymerised at the inlet of the m-PADs.The ionogels remain mainly on the surface of the paper and get absorbed in the superficial paper-fibers allowing for the liquid to flow from the ionogel into the paper easily. As a proof of concept the fluid flowand mixing behaviour of two different ionogels mPADs were compared with the non-treated mPADs.It was demonstrated that both ionogels highly affect the fluid flow by delaying the flow due to their different physical and chemical properties and water holding capacities.

[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.

Parasitic diseases have a great impact in human and animal health. The gold standard for the diagnosis of the majority of parasitic infections is still conventional microscopy, which presents important limitations in terms of sensitivity and specificity and commonly requires highly trained technicians. More accurate molecular-based diagnostic tools are needed for the implementation of early detection, effective treatments and massive screenings with high-throughput capacities. In this respect, sensitive and affordable devices could greatly impact on sustainable control programmes which exist against parasitic diseases, especially in low income settings. Proteomics and nanotechnology approaches are valuable tools for sensing pathogens and host alteration signatures within microfluidic detection platforms. These new devices might provide novel solutions to fight parasitic diseases. Newly described specific parasite derived products with immune-modulatory properties have been postulated as the best candidates for the early and accurate detection of parasitic infections as well as for the blockage of parasite development. This review provides the most recent methodological and technological advances with great potential for biosensing parasites in their hosts, showing the newest opportunities offered by modern “-omics” and platforms for parasite detection and control

[EN] This paper reports an innovative technique for reagents storage in microfluidic devices by means of a one-step UV-photoprintable ionogel-based microarray on non-modified polymeric substrates. Although the ionogel and the ink-jet printing technology are well published, this is the first study where both are used for long-term reagent storage in lab-on-a-chip devices. This technology for reagent storage is perfectly compatible with mass production fabrication processes since pre-treatment of the device substrate is not necessary and inkjet printing allows for an efficient reagent deposition process. The functionality of this microarray is demonstrated by testing the release of biotin-647 after being stored for 1 month at room temperature. Analysis of the fluorescence of the ionogel-based microarray that contains biotin-647 demonstrated that 90% of the biotin-647 present was released from the ionogel-based microarray after pumping PBS 0.1% Tween at 37 °C. Moreover, the activity of biotin-647 after being released from the ionogel-based microarray was investigated trough the binding capability of this biotin to a microcontact printed chip surface with avidin. These findings pave the way for a novel, one-step, cheap and mass production on-chip reagents storage method applicable to other reagents such as antibodies and proteins and enzymes.