Transition between circular fronts and spiral waves in marginally excitable media

Abstract

Belousov–Zhabotinsky (BZ)-type waves are studied on a polysulfone membrane loaded with bathoferroin catalyst. The membrane is placed on a glass-fibre filter-disc soaked with a BZ medium containing no catalyst. Waves are periodically initiated on the membrane surface by using silver- and platinum-wire electrodes. When the area around the silver electrode is made marginally excitable by sufficiently shortening the period of perturbations, an unusual transition between circular fronts and spiral waves is observed.