Youssef Fahmy
Brandeis University / Physics
Hosted by Fraden's Lab
“Controlling Networks of Microfluidic Chemical Oscillators”
Youssef Fahmy, Ian Hunter, Mike Norton, Seth Fraden
Abstract
Chemical reactions such as the oscillating Belousov-Zhabotinsky (BZ) reaction can be used to model nervous systems. To do this, the BZ reaction is placed in grids of microfluidic PDMS wells which are fabricated on a microscope slide. This ensures homogeneity and allows multiple simultaneous experiments. In the reaction, bromine is able to diffuse across the semipermeable PDMS boundaries between the wells creating coupled nearest-neighbor networks.
One problem with studying the BZ is the dramatic temperature dependence of the period of oscillation. Since microscope slides are completely uninsulated, control over their temperature is difficult. Additionally, they must be imaged and illuminated along at least one axis to properly view the sample in interest.
To solve this problem, four aluminum clamps were manufactured to hold the setup for the experiments and control the temperature using a Proportional-Integral-Derivative feedback loop. They were designed to control to a set temperature while allowing the reaction to be observed by a modified microscope and camera. Thermistors embedded in the clamps provide electronic temperature measurement and a pair of thermoelectric coolers heat or cool the device and corresponding reactions as necessary. Using these devices, experiments have been performed with a constant temperature accuracy of at least 0.02 C, at a much lower cost than commercially available. Although the reaction temperature cannot be measured during an experiment, the setup was calibrated so that the device control temperature correlates with the reaction temperature. In the future, the devices will be used to create temperature gradients across the grids and perturbations in temperature as the reaction progresses.
Support
SMURF (Summer MRSEC Undergrad Research Fellowship)