Helicoidal precipitation patterns in silica and agarose gels

Helicoidal patterns grown in agarose and silica gels were studied using reaction–diffusion–precipitation processes with components CuCl2/K2CrO4. We measured the probability PH of the emergence of helicoids as the internal surface area of the gels was varied by changing the concentration for agarose and by modifying pH for silica. In addition, the effects of mixing the two gels were also investigated. Our main result is that the surface area effects parallel the effects of noise, namely increasing the surface area initially enhances the formation of helicoids but further increase leads to downturn in PH due to proliferation of random patterns.