| Calorimetry is a valuable tool in pharmaceutical, biochemical and clinical diagnostic application areas. Thermodynamic quantities such as enthalpy of reaction are an indication of the efficacy of the interaction between active compounds. This information can enable acceleration of the drug development process by facilitating proper selection of the most promising compounds for later stages of development. A microfluidic calorimeter is being developed which offers reduced compound consumption, shorter experiment time, and higher throughput. The calorimeter employs a novel optical sensor based on the extraordinary optical transmission (EOT) of light through nanohole arrays (NHAs) which offers fine temperature and spatial resolution. Thermodynamic quantities such as enthalpy of reaction and binding constant can then be extracted from the temperature and concentration measurements.;A 3-D computational fluid dynamics (CFD) simulation was performed with the commercial package ANSYS Fluent to understand the momentum, heat and mass transport within the device for the reaction of calcium chloride with EDTA. A simplified reaction model for the formation of the calcium-EDTA complex was developed. The temperature and concentration fields for several different cases were analyzed to assess the viability of the device and determine the effect of changing the flow rate and reactant concentration. The original intent was to mix 1mM CaCl2 solution with 0.1mM EDTA at a flow rate of 5 ul/min. It was found that this set of parameters did not produce a large enough temperature change within the device, limiting its use as a calorimeter. It was then found that higher heat release can be achieved by increasing reactant concentration or flow rate, at the expense of reactant quantity consumed per experiment. The flow rate is also directly related to the width of the diffusion region, the distribution of the chemical reaction heat source, and the shape of the resulting thermal plume. |
