LAUSR

Abstract Inexpensive in situ monitoring of a conformational change in a macro object over long periods of time in a chemical reactor is challenging. One research area which would benefit from improvements in screening methods is the study of smart hydrogels, particularly when they are intended as oral forms for drug delivery or as multifunctional scaffolds replacing surgically removed tissues. Smart materials have the ability to alter their volume by swelling and/or collapsing in response to a specific stimulus in their environment. Conventional methods used to record this change such as gravimetric analysis, are invasive, require manpower for time-consuming hydrogel handling and often result in material fragmentation leading to inaccuracy. In this work, a novel reactor design is implemented in combination with inexpensive optics to achieve a non-invasive method that can be used reliably over long periods of time. Optical quality flat glass windows are incorporated in a jacketed reactor vessel design to enable undistorted imaging. The reactor was made from a chemical engineering viewpoint to enable temperature control, continuous stirring and sampling while preventing evaporative loss of solvent. Image resolution was measured using a USAF 1951 resolution test target. The setup was validated using pH responsive PVP-Chitosan hydrogels to demonstrate the capabilities of the method in monitoring the change in volume of the responsive hydrogel with time.