No abstract

Herein we describe poly(ionic liquid) hydrogel actuators that are capable of responding to multiple stimuli, namely temperature, ionic strength and white light irradiation. Using two starting materials, a crosslinked poly ionic liquid (PIL) and a linear poly(N-isopropylacrylamide-co-spiropyran-co-acrylic acid), several semi-interpenetrating (sIPN) hydrogels were synthesised. The dimensions of hydrogels discs were measured before and after applying the stimuli, to quantify their response. Samples composed of 100% crosslinked PIL alone showed an average area reduction value of ~53% when the temperature was raised from 20 °C to 70 °C, ~24% when immersed in 1% w/w NaF salt solution and no observable photo-response. In comparison, sIPNs containing 300% w/w linear polymer showed an average area reduction of ~45% when the temperature was raised from 20 °C to 70 °C, ~36% when immersed in 1% NaF w/w salt solution and ~10% after 30 min exposure to white light irradiation, respectively. Moreover, by varying the content of the linear component, fine-control over the photo-, thermo- and salt response, swelling-deswelling rate and mechanical properties of the resulting sIPN was achieved.

In this study we report the synthesis, characterisation and performance of thermoresponsive crosslinked tributylhexyl phosphonium sulfopropylacrylate (PSPA) poly(ionic liquid) (PILc) hydrogels as temperature controlled valves 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.

This paper describes the design, fabrication and performance of a reusable ionogel-based photoactuator, in-situ photopolymerised into a lab-on-a-disc microfluidic device, for flow control. The the ionogel provides an effective barrier to liquids during storage of reagents and spinning of the disc. A simple LED (white light) triggers actuation of the ionogel for selective and precise channel opening at a desired location and time. The mechanism of actuation is reversible, and regeneration of the actuator is possible with an acid chloride solution. In order to achieve regeneration, the Lab-on-a-Disc device was designed with a microchannel connected perpendicularly to the bottom of the ionogel actuator (regeneration channel). This configuration allows the acid solution to reach the actuator, independently from the main channel, which initiates ionogel swelling and main channel closure, and thereby enables reusability of the whole device.

No abstract

HighlightsThe article presents pioneering research of textile chemiresistors on Evolon and Polyester substrates equipped with graphite electrodes and in-situ polymerized poly(tetrabutylphosphonium 3-sulfopropylacrylate) or poly(tributylhexylphosphonium 3-sulfopropylacrylate) sensitive layers. The DC-and AC-responses to 10 ppm of methanol, nitrogen dioxide, 4-bromoacetophenone, diethylmalonate and yperite were then investigated at laboratory temperature -the reference was "pure" synthetic air. Under these circumstances the DC-responses (SDC) varied from 0.48 to 1.36 and maximum AC-responses (Spa) from 8 to 26 deg. It was shown that sensor dynamics depends mainly on molecular weight of the analytes. Moreover, the magnitude of AC-responses correlated both qualitatively and quantitatively with the dipole moments of the analyzed molecules.

“Lab-on-a-chip” (LOC) and microfluidics enable the manipulation of fluids at small length scales (from micrometers to millimeters). These systems often have well-defined fabrication processes and are capable of integrating multiple functional elements, to provide complete sample-in/answer-out systems. Nevertheless, the development of fully integrated microfluidic devices still faces some considerable obstacles, including fluidic control, miniaturisation and high costs. Due to their unique properties, ionic liquids have arisen as smart solutions to circumvent some of the hurdles facing current LOC technologies. They can directly benefit microfluidic devices by aiding miniaturised fabrication and passive microfluidic elements for fluid control, sensing and sample storage. Improved chemical reactions and separation, in addition to power generation, temperature control, and electrowetting show potential for reducing manufacturing costs and widening market possibilities. In this chapter we will review and discuss the fundamental applications of ionic liquids within microfluidic systems.

Abstract. POLITO is a free, open-source, and platform-independent software which can automatically generate lithostratigraphic columns from field data. Its simple and easy to use interface allows users to manipulate large datasets and create high-quality graphical outputs, either in editable vector or raster format, or as PDF files. POLITO uses USGS standard lithology patterns and can be downloaded from its Sourceforge project page (http://sourceforge.net/projects/polito/).