Susan Okrah


Hampton University / Chemical Engineering
Hosted by Fraden's Lab
Observations of Three Ringed Networks of BZ Droplets
Susan Okrah*, Jesse Held, Nate Tompkins, Seth Fraden
Abstract:  Synchronization is a critical of the cardiovascular system. When a person has a cardiac arrest or a heart murmur, the rhythm of their heart is changed. Because the heart is a complex network to study, we use a simpler network with similar qualities to study these patterns. The Belousov- Zhabotinsky reaction or BZ reaction is a nonlinear chemical oscillator. Just like the heart, BZ has a specific synchronization pattern. Over a period of time, this coupled oscillator continually changes from a red reduced state to a blue oxidized state. For this research, we wanted to observe a ring network of BZ. As a wave traveled in one direction in this network, we wanted to find a way to switch the direction of the wave by inhibiting a single drop. Using a microfluidic drop maker, droplets of a consistent size were then observed in one of two environments: capillaries or silicon chips. For capillaries, precut capillaries filled with these droplets were attached to a glass slide using an epoxy mixture. For silicon chips, the BZ droplets were carefully squeezed onto the desired etching, sealed with a glass slide and placed in a special clamping device. For both methods, observations were recorded using the Programmable Illumination Microscope, or PIM. In capillaries, we observed two isolated rings spontaneously switch direction after two droplets in the ring simultaneously oscillated. In silicon chips, a new sloshing state was observed. Instead of completing a full cycle through all three droplets, the ring continually switches direction. As a future direction, we want to continue engineer a method to control the direction of these rings. We also want to find and examine the parameters that cause the sloshing state to occur.
Support: MRSEC REU