Photo-responsive materials as sensors and actuators in microfluidic devices

The integration of photo-responsive materials into microfluidic systems can provide unprecedented versatility and external flow control. Herein we present several approaches for introducing fluid movement and sensing using smart materials in microfluidics. The first approach comprises the use of adaptive nanostructured coatings for direct sensing of flow in continuous flow mode. The optical proprieties of these coatings change in response to a variety of target analytical species passing through the microfluidic device in continuous flow mode [1, 2]. The second approach uses spiropyran photo-switches for photo-modulation of flow in microfluidic devices. This was realised through the use of photo-actuated hydrogels as micro-valves for repeatable ON/OFF flow modulation, or through photo-controlled movement of synthetic micrometre size droplets [3]. We envision using these systems to create a new generation of sustainable, low-cost, photonically-controlled and self-reporting fluidic systems. 1. Florea, L. et al., Lab Chip 2013, 13, (6), 1079-1085. 2. Florea, L, et al., Langmuir 2013, 29, (8), 2790-2797. 3. Florea, L, et al., Adv. Mater. 2014. 26 (43), 7339-7345.