Optical microscopy measurements of kT-scale colloidal interactions

Understanding colloidal assembly processes requires knowledge of interactions between colloids, surfaces, and external fields on the scale of the thermal energy, kT. In this review, we discuss recent advances in the development of non-intrusive optical microscopy methods to measure kT-scale colloidal interactions. We begin with a brief historical overview of quantitative optical microscopy measurements of colloidal interactions, which provides a precedent for emerging techniques. We then review recent advances in methods and analyses associated with Total Internal Reflection Microscopy (TIRM), Video Microscopy (VM), and Confocal Scanning Laser Microscopy (CSLM). We limit the scope of this review to the use of these methods for quantitative measurements of kT-scale colloidal interactions. We also discuss how these methods can be used in an integrated fashion to measure complementary quantities based on each methodʹs strengths. Finally, we conclude with an overview of current and future trends related to both method development and new applications.