“Photosensitivity of a Single-Well Chemical Oscillator”
The Belousov-Zhabotinsky (BZ) reaction is a non-linear chemical oscillator which cycles between two visibly distinct states: an oxidized (blue) and a reduced (red) state. The photosensitive ruthenium catalyst causes the reaction to produce the inhibitor bromine. When light is applied, the reaction produces more inhibitor, delaying or completely suppressing oscillations when the correct light intensity is applied. Current experimental methods confine the BZ reaction into a single solid elastomeric polydimethylsiloxane (PDMS) well network made with the use of microfluidic techniques. Boundary conditions are established by applying a minimum intensity of light to suppress oscillations within the reservoir surrounding each BZ well.
In this work, we define how light influences the dynamics of a single-well chemical-oscillator. First, we compare the period of chemical oscillations over a range of light intensities for two different ruthenium catalysts: ruthenium-chloride and ruthenium-sulfide. We find that the ruthenium-sulfide catalyzed chemical oscillations are more photosensitive. Next, we alter the duration of light incubation and light sequences for both ruthenium catalysts and and observe the period of chemical oscillation. Our results suggest that longer incubation time increases BZ photosensitivity. Finally, we assess the effects of well size on the period of oscillation. Our results indicate that well size does not affect photosensitivity. Each of these findings provide a variable of control for complex PDMS well systems modeling more complex spatio-temporal patterns such as neural networks or a chiral three ring network.