Lowest Detectable Protein Immobilization Measurement Using an Ultrasensitive Micropillar-Based Quartz Crystal Microbalance (QCM-P) Device

Development of new sensing techniques to achieve the lowest detection limit of analyte is vital for clinical measurements, such as drug testing, tumor indicators, thyroid-stimulating hormone, and similar immunoassay examinations. It has been reported that a polymer micropillar array appended to a quartz crystal microbalance substrate (QCM-P) forms a two-degree-of-freedom vibration system that was able to significantly improve the sensitivity of conventional QCM systems. This paper focuses on the development of a theoretical model for sensitivity determination of the QCM-P devices. To validate the model, a commercially available QCM platform, qCell T, was utilized to operate the QCM-P device and the adsorption of bovine serum albumin (BSA) protein with varied concentrations was measured with the system. A five-fold enhancement in sensitivity over a traditional film-based QCM (QCM-F) was demonstrated. In addition, it shows that the QCM-P had the capability to detect the BSA protein at very low concentrations approaching 0.3 mu g/mL.