ASG members Bartosz Ziolkowski and Monika Czugała were among those who made presentations for the recent international conference: ‘Water: the greatest global challenge’, held in the Helix, Dublin City University (DCU) from the 14th – 16th May 2013. Bartosz and Kevin Fraser presented on the day.
This conference was a great success overall. For further information please see the NCSR and ATWARM websites.
Novel, stimuli-responsive materials for fluid handling in microfluidic sensor platforms
Bartosz Ziółkowski and Dermot Diamond (CLARITY: The Centre for Sensor Web Technologies, Dublin City University, Dublin 9, Ireland.)
Smart materials have been a subject of research as potential candidates for fluid handling actuators for some time. They have been said to allow miniaturisation of autonomous analytical platforms and decrease of their cost. Current autonomous sensor platforms cost >20 k€, 60% of which is sample handling components. To address this issue, gels that change volume under light stimuli have been developed as remotely triggered, low power and inexpensive microfluidic valves [2, 3].
Materials research in this area has been mostly based on poly(N-isopropylacrylamide) a thermo responsive polymer with a lower critical solution temperature (LCST) at ~30 ˚C. However, recently polymerisable ionic liquids having LCST have been reported. Therefore, these materials are good candidates for a new class of poly-ionic liquid responsive gels.
Here we report two ionic liquids: tetrabutyl-phosphonium-4-vinylbenzenesulfonate and tributyl-hexyl-phosphonium-3-sulfopropyl acrylate that have been polymerised with a crosslinker. These materials if placed in water quickly swell and form hydrogels within one hour. The amount of crosslinker used determined the swelling of the gel and the amount of water uptake. Since the LCST of this IL is concentration dependant we show that it can be controlled by the crosslinker amount. The LCST has been demonstrated to decrease as the crosslinker amount increased. These gels exhibited good mechanical properties and reversible shrinking by 40 % volume when heated to 60 ˚C. This demonstrates the first thermoresponsive poly ionic liquid hydrogel with potential application in microfluidic devices and sensors.
 M. Sequeira, M. Bowden, E. Minogue, D. Diamond, Talanta 56 (2002) 355. T. Boone, Z.H. Fan, H. Hooper, A. Ricco, H.D. Tan, S. Williams, Anal. Chem. 74 (2002) 78A.  J. Siegrist, R. Gorkin, M. Bastien, G. Stewart, R. Peytavi, H. Kido, Lab Chip, 10 (2010) 363.
Fully integrated portable Centrifugal Microfluidic Analysis System for on-site colorimetric water analysis
Monika Czugala, Damian Maher, Robert Burger, Kevin J. Fraser, Jens Ducree, Dermot Diamond and Fernando Benito-Lopez.(CLARITY: Centre for Sensor Web Technology,School of Physical Sciences, National Centre for Sensor Research, Dublin City University, Dublin, IRELAND)
Miniaturization of analytical devices through the advent of microfluidics is an important step forward for such applications as environmental monitoring. Micro total analysis systems provide a route to the generation of micro-dimensioned analytical instruments that could be operated in remote locations, enabling in-situ water analysis [1, 2]. In this work we report a portable, wireless system capable of in situ reagent-based colorimetric water analysis. The system is based on a reconfigurable low cost optical detection method employing a paired emitter detector diode device, which allows a wide range of centrifugal microfluidic layouts to be implemented. Due to the wireless communication, acquisition parameters can be controlled remotely and results can be downloaded in distant locations and displayed in real time. The autonomous capabilities of the system, combined with the portability and wireless communication, provide the flexibility crucial for on-site water monitoring. The system is based on microfluidic centrifugal platforms which offer many advantages over standard lab-on-a-chip systems such as the elimination of large power supplies and external pumps . The presented centrifugal microfluidic platforms allow for monitoring of such parameters as nitrite, pH and turbidity of water samples. The strong correlation between the results obtained using the PEDD system and a standard bench-top instruments was achieved
Fig. 1. Portable Android controller and CMAS with centrifugal microfluidic platform.
References: M. Sequeira, M. Bowden, E. Minogue, D. Diamond, Talanta 56 (2002) 355.  T. Boone, Z.H. Fan, H. Hooper, A. Ricco, H.D. Tan, S. Williams, Anal. Chem. 74 (2002) 78A.  J. Siegrist, R. Gorkin, M. Bastien, G. Stewart, R. Peytavi, H. Kido, Lab Chip, 10 (2010) 363.