Microfluidic Systems for the Belousov−Zhabotinsky Reaction

We describe an experimental methodology for the study of chemical self-organization in micropatterned reaction systems. Our approach is based on office-printer-assisted soft lithography and allows the fabrication of centimeter-scale devices with reactor units as small as 50 μm. The devices are made from the elastomeric material poly(dimethylsiloxane) and are filled with a modified Belousov−Zhabotinsky solution. This excitable reaction−diffusion medium employs 1,4-cyclohexanedione as a bubble-free organic substrate and Fe(II)[batho(SO₃)₂]₃ as a high-absorbance redox catalyst/indicator. Chemical wave propagation is affected by the loss of bromine from the aqueous phase into the elastomer matrix. The strength of this activating process depends on the local surface-to-volume ratio and can increase the wave velocity by a factor of 2. For devices with gridlike reactor networks, we observe a pronounced deformation of target patterns and the pinning of spiral waves to single elastomer obstacles as well as to obstacle clusters.