Dr. Anuj Chauhan

Research Summary:

DESIGN OF EXTENDED WEAR CONTACT LENSES Our research efforts are directed towards developing an extended wear soft contact lens. Currently, the extended wear of soft contact lens is known to significantly increase the risk of bacterial infection to the cornea. We believe that this enhanced risk is due to a lack of good mixing between the tear film sandwiched between the cornea and the lens called Post Lens Tear Film (POLTF) and the tear meniscus. Due to lack of mixing, bacteria and cell debris gets trapped in the POLTF. In addition, the small flow in the POLTF results in small shear on the corneal surface and so it's much easier for the bacteria to attach itself to the corneal surface. These factors result in an increase in the risk of infection. Since, the major cause of the infections is the lack of mixing in the POLTF, our efforts are focused on developing lens designs that will have a higher degree of mixing. According to a mechanistic model developed by Radke and Creech, the tear mixing is driven by the periodic squeeze and couette flow in the POTF caused by the action of the eye-lid during the blink. This periodic flow increases the effective dispersivity as in the classical Taylor Dispersion problem. Since, the mixing is driven by motion of the lens, we are developing a model to predict the motion of the lens in the lateral and the transverse directions during the blink and the interblink period. In addition to modeling the motion, we are working on new designs that will increase the motion of the lens and thus increase mixing.

SPREADING OF AQUEOUS SURFACTANT SOLUTIONS ON HYDROPHOBIC SURFACES The spreading of a liquid on a second, immiscible liquid or solid substrate is of considerable importance in environmental, chemical, petroleum, and biotechnology applications. Spreading of aqueous drops on hydrophobic surfaces occur only when particular surfactants are added to the droplets above a critical concentration. We are modeling the surfactant driven spreading of aqueous solutions on liquid and solid hydrophobic surfaces. The aim of the study is to understand the mechanisms of the spreading so as to be able to determine the optimum surfactant concentration to cause spreading