Polystyrene Micro-pools Distribution on Quartz Crystal Microbalance (QCM) Surface using Ultrasonic Atomization Spray Coating

Abstract

Surface morphology of polystyrene thin film is one of the significant factors to be take into account in the development of quartz crystal microbalance (QCM) as biosensor and chemical sensor. Many coating methods were developed to modify the morphology of polystyrene thin film surface. Our previous study showed that ultrasonic atomization spray coating (UASC) is a promised coating method to produce a rough polystyrene thin film on QCM sensor with patterns called micro-pools. There are many parameters that can affect the uniformity of micro-pools produced by UASC. In this work, 0.5% polystyrene solution which was solved in toluene was used as material coated onto a QCM sensor using UASC method. The effect of the distance variation between the spray nozzle and specimen towards the surface morphology of polystyrene thin film was observed. The surface morphology of the coated polystyrene and the micro-pools distribution were characterized by an optical microscope and Scanning Electron Microscope (SEM). The electrical impedance of the QCM was measured and characterized using Impedance Analyzer. The result showed that the optimum distance of the spray nozzle and specimen is between the range of 15 until 24 cm. At this optimum distance, the uniform micro-pools distribution was formed on the QCM surface without influencing the QCM acoustic impedance.