We present the fabrication, characterisation and performance of four novel ionic liquid polymer gels (ionogels) as photo-actuated valves incorporated into microfluidic 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.

The photo-, thermo-and solvatochromic properties of 2,3-dihydro-1 0 ,3 0 ,3 0 -trimethyl-6-nitrospiro[1-benzopyran-2,2 0 -1H-indole] (BSP) and its photo-induced merocyanine isomer (MC)were investigated in phosphonium based ILs by UV-vis absorption spectroscopy. It was found that the kinetics and thermodynamics of the BSP 2 MC equilibrium were sensitive to the nature of the anion. The MC l max shifted from 560 nm to 578 nm when in solutions of [P 1,4,4,4 ][tos] and [P 6,6,6,14

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