title: Ionogel-based light-actuated valves for controlling liquid flow in micro-fluidic manifolds.
abstract: We present the fabrication, characterisation and performance of four novel ionic liquid polymer gels (ionogels) as photo-actuated valves incorporated into micro-fluidic manifolds. The ionogels incorporate benzospiropyran units and phosphonium-based ionic liquids. Each ionogel is photo-polymerised in situ in the channels of a poly(methyl methacrylate) micro-fluidic device, generating a manifold incorporating four different micro-valves. The valves are actuated by simply applying localised white light irradiation, meaning that no physical contact between the actuation impulse (light) and the valve structure is required. Through variation of the composition of the ionogels, each of the micro-valves can be tuned to open at different times under similar illumination conditions. Therefore, flows through the manifold can be independently controlled by a single light source. At present, the contraction process to open the channel is relatively rapid (seconds) while the recovery (expansion) process to re-close the channel is relatively slow (minutes), meaning that the valve, in its current form, is better suited for single-actuation events.
authors.affiliation: CLARITY: Centre for Sensor Web Technologies, National Centre for Sensor Research, School of Chemical Sciences, Dublin City University, Dublin, 9, Ireland. fernando.lopez@dcu.ie
authors.forename: Fernando
authors.initials: F
authors.lastname: Benito-Lopez
authors.forename: Robert
authors.initials: R
authors.lastname: Byrne
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Răduţă
authors.forename: Nihal Engin
authors.initials: NE
authors.lastname: Vrana
authors.forename: Garrett
authors.initials: G
authors.lastname: McGuinness
authors.forename: Dermot
authors.initials: D
authors.lastname: Diamond
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D005782:Gels / Q000737:chemistry* / Q000528:radiation effects; D007477:Ions; D008027:Light; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D055096:Optical Devices; D012996:Solutions / Q000737:chemistry*; D014159:Transducers
chemical_list: D005782:Gels; D007477:Ions; D012996:Solutions