Quartz crystal microbalances (QCMs) have found applications as popular chemical and biological sensing tools. However, their current device geometry prevents their commercialization for industrial use. In this study, we propose a new disposable QCM sensor with an electrode only on the sensing side, making it suitable for sensor mounting. In this sensor system, the excitation electrode is positioned on a glass plate separate from the QCM. Such electrode configurations are suitable for sensor applications in flow cell systems in preference to common QCM systems because QCM mounting on the flow cell and the electrical interconnections between the QCM and the oscillation circuit are simple. The optimized configurations of the electrode diameter, separation distance, and orientation relative to the crystallographic x-axis of the plate are revealed for the first time. The proposed QCM can be applied to realize a disposable QCM-based biochip or hazardous gas sensor located inside a flow tube.