Effects of the Light Source on the Signal Quality for Photonic and Microfluidic Nanohole Sensor Calorimeter

Our research focuses on the development of a calorimeter device utilizing a photonic temperature sensor based on the extraordinary optical tranmission (EOT) signals through nanohole array (NHA) sensors on metallic films in combination with a continuous coflow reactor clamped to the sensor chip. The fluid was in direct contact with the gold. The incident light traversed the layers of the flowcell assembly to illuminate the sensors, and was measured using a CCD camera. Here, the effect of the light source and the flowcell material and design on the signal quality is reported. Using an incoherent light source and eliminating elastic deformation from the illumination path resulted in an interference-free, fringe-free optical configuration. Using the improved apparatus, EOT signal temperature dependence for different liquids (DI water and ethanol) was presented. EOT signal gain due to a temperature change was 3.810 times higher in the ethanol than the DI water signal gain. This behavior was explained by the difference in the volumetric expansion coefficient, which is a factor in the change of dielectric constant due to temperature changes. This trend was in agreement with the analytical relations and supports the use of EOT as a measurement signal in a miniaturized calorimeter.Copyright © 2012 by ASME