Detecting Proteins in Microfluidic Channels Decorated with Liquid Crystal Sensing Dots

In this paper, we report the integration of liquid crystal (LC) dots on microfluidic channels as microscopic protein sensors. Flexibility of patterning LC dots on a surface to fit small microfluidic channels is achieved by using inkjet printing technology. These LC dots (1 pL) remain stable when they are subjected to flowing buffer solution at a high flow velocity (v ≥ 0.198 cm/s). When the buffer solution contains protein, such as bovine serum albumin (BSA), it causes a change in the orientational ordering of the LC dots as indicated by a distinct dark-to-bright transition in the optical appearance of the LC dots. Moreover, we are able estimate the concentration of BSA by simply counting the number of bright LC dot sections. This microscopic protein sensor has potential applications in the real-time detection and quantification of proteins in aqueous solutions. This detection method is advantageous because protein labeling and complex instrumentation are not required.