The exciting potential of stimuli-responsive materials and biomimetic microfluidics

Our capacity to create and characterise structures with 3D spatial control ranging from molecular scale through nano, to micro and even macro dimensions opens exciting new opportunities to understand and mimic the molecular world of biology and chemistry. For example, complex 3D structures can now be formed from soft gel-polymers with sub-micron resolution, enabling pores with pre-determined topographies to be created within films and beads. When these polymers incorporate a photo-switchable or chemo-switchable moiety, the pore dimensions can be controlled using light or changes in the local chemical environment. This in turn enables uptake or transfer of material through the pores to be controlled, in a manner similar to many bio-systems. Furthermore, nano-dimensioned features can be created inside microfluidic channels to produce soft polymer actuators for fluid control, or channels with switchable characteristics such as surface roughness [1], or controlled uptake and release of molecular guests. In addition, fluidic coatings can optically report their condition (e.g. whether they are in binding or passive form, or molecular guests are bound) reflecting the chemical status along the entire length of the fluidic system, rather than at a localised detector [2]. The same characteristics can be integrated into micro-vehicles such as droplets, beads and vesicles, or microrobots that can also move spontaneously or be externally directed to specific locations, where they can perform these and other tasks [3, 4]. In this paper, we will present routes through which these exciting concepts can be practically realized. References 1. J.E. Stumpel, B. Ziolkowski, L. Florea, D. Diamond, D.J. Broer, A. Schenning, Acs Applied Materials & Interfaces, 6 (2014) 7268-7274. 2. L. Florea, C. Fay, E. Lahiff, T. Phelan, N.E. O'Connor, B. Corcoran, D. Diamond, F. Benito-Lopez, Lab on a Chip, 13 (2013) 1079-1085. 3. L. Florea, K. Wagner, P. Wagner, G. G. Wallace, F. Benito‐Lopez, D. L. Officer, D. Diamond, Adv. Mater. 26, 7339 (2014). 4. W. Francis, C. Fay, L. Florea, D. Diamond, Chem. Commun. 51, 2342 (2015)