Flow rate effect of syringe pump on quartz crystal microbalance sensor resonance frequency stability

Most Quartz Crystal Microbalance biosensor system works in liquid phase utilizing flow injection system using a continuous peristaltic pump with electronic control. In the development of QCM sensor as a disposable system, sample injection using a syringe pump will be a candidate option as it can be operated manually. In this work, a flow rate effect of the microsyringe pump on the frequency stability of quartz crystal microbalance resonance during injection is investigated. Flow rate in a closed pipe causes a pressure change of the liquid on top of the sensor. Therefore, it can affect the resonance frequency of the sensor. In this work, a microliter syringe pump with a maximum volume of 100μL is used. Sensor response is observed in two pumping directions, which is injection and ejection of liquid. At beginning 50μL water was injected on top of the sensor surface. This volume fills the chamber of the sensor cell of 30μL. After it steady frequency in contact with water; the water is ejected for 20μL and then injected back for 15μL. The sequence was repeated several times by changing injection and ejection speed. At a flow rate of less than 0.17μL/second the frequency change of the sensor resonance frequency during injection into the chamber change by 1-2 Hz. At liquid ejection, the frequency of the sensor is still.