Chemical Wave Propagation in the Belousov–Zhabotinsky Reaction Controlled by Electrical Potential

Abstract

The Belousov−Zhabotinsky (BZ) reaction is an important experimental model for the study of chemical oscillations and waves far from the thermodynamic equilibrium. Earlier studies had observed that individual BZ microbeads can show both global oscillations and traveling waves, but failed to select these different dynamic states. Here, we report experiments, in which this control was achieved by an externally applied electrical potential. The spherical microbeads were first loaded with the catalyst, then immersed into a catalyst-free BZ solution, and finally placed onto a planar platinum electrode. For positive electrical potentials, we observed global oscillations, whereas negative potentials resulted in traveling waves. The spatio-temporal characteristics of these phenomena are discussed in relation to the activator, HBrO 2 , which is produced by an electrochemical reaction.

Applications of Information Theory Methods for Evolutionary Optimization of Chemical Computers

“…A high uniformity of droplets that form the network can be achieved if droplets are generated in a microfluidic device [ 32 ]. One can also use DOVEX beads or silica balls [ 33 ] to immobilize the catalyst and inhibit oscillations by illumination or electric potential [ 34 ].…”

How Does a Simple Network of Chemical Oscillators See the Japanese Flag?

“…The bubbles of gas can appear between droplets, deform them, and change interactions between oscillators. We therefore believe that solid objects loaded with the catalyst, like DOWEX beads (Kuze et al, 2019 ) or silica gel beads (Mallphanov and Vanag, 2020 ), seem to be more suitable for experiments with information processing using a network of oscillators. Also, the strategy of optical communication described by Gentili et al ( 2017 ) can be applied to control interactions between oscillators and the inflow of input data.…”

Identification of the best medium for experiments on chemical computation with Belousov–Zhabotinsky reaction and ferroin-loaded Dowex beads

“…BZ reaction can be influenced by light [4,27], sound [28], and electric potential [29,30]. We are currently interested in the latest because the electrical interface using a potentiostat can switch between the regimes of travelling waves (TW) or global oscillations (GO) [30,31].…”

“…Therefore, such system is interesting for chemical computing applications. Negatively polarized working electrode of potentiostat forms activator species HBrO 2 , according to reaction: BrO 3 − + 2e − + 3H + → HBrO 2 + H 2 O [29]. Positive electric potential on the working electrode attracts the inhibitor species Br − from the solution near the working electrode.…”