New Ultraviolet (UV) Light Intensity Sensor Using Photo-rheological Fluids

초록

This research presents a state-of-art ultraviolet (UV) light intensity sensor using the photo-rheological (PR) fluid whose rheological behavior can be changed by ultraviolet (UV) light with a wavelength of 365 nm. When the PR fluid was exposed to UV light, the viscosity of PR fluid becomes decreased, while viscosity recovered its initial value when UV light was turned off, which implies that the viscosity of PR fluid can be reversible, and tunable by light [1]. In addition, the color of PRFs is changed from yellow to red. The PR phenomenon results from the interaction of the phospholipid lecithin and sodium deoxycholate (SDC) in an organic solvent such as cyclohexane. In the presence of SDC, before UV irradiation, spiropyran (SP) remains in the hydrophobic state, and the head-group of lecithin and SDC interact with each other. The hydrophobic tails of lecithin act as nets and the micelles have a wormlike shape, as shown in Figure 1. Upon UV irradiation, the SP is converted to merocyanine (MC), which is hydrophilic and hence shifts to the head-group area of lecithin, which results in the color of PRFs changing from yellow to red. In this study, the PRFs were used as colorimetric sensors of UV light intensity. We will report the PR fluids that cana exhibit the colorimetric response to changes in UV light intensity