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, thyroidstimulating 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 twodegree-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 μg/mL.