Photo-patterning of ionogel microstructures for on-chip microvalve applications controlled by fiber optics

The photo-patterning of photoresponsive N-isopropylacrylamide based ionogel microstructures is investigated. The ionogels are synthesised using phosphonium based room temperature ionic liquids together with a photochromic compound benzospiropyran. These stimuli responsive materials can be actuated simply by using light irradiation, facilitating non-contact and non invasive operation. For the first time, the characterisation of the swelling and shrinking behavior of ionogel microstructures is evaluated. Next, the ionogel was successfully applied as microvalve and the performance within a hybrid PDMS/glass microchip actuated using fiber optics is presented. It was found that the actuation behavior of the ionogels is strongly dependent on the nature of the anion of the ionic liquid. In particular, the [P_{6, 6, 6, 14}][NTf₂] ionogel exhibits the greatest degree of swelling and the fastest shrinkage behaviour.