Optical Quartz Crystal Microbalance (OQCM) for Dual-Mode Analysis

Abstract:

Label-free biosensors allow for real-time measurements of the target molecule, providing valuable kinetic data about the unperturbed biological system. These sensors generally rely on a single transduction mechanism that reflects a single aspect of a system. An integrated multi-mode label-free sensor capable of providing consistent and complementary information about multiple aspects of a system is highly desirable for biomedical research. However, currently those hybrid sensors have some shortcomings in implementation and performance that limit their applicability.

In this research, we developed the Optical Quartz Crystal Microbalance (OQCM), a hybrid sensor utilizing optical and QCM techniques for simultaneously measuring both optical and mechanical properties of a system to address these shortcomings. Two OQCM structures were fabricated and explored: 1) the Interferometric OQCM (I-OQCM) sensor; 2) the Plasmonically-Enhanced Grating OQCM (PEG-OQCM) sensor.

The OQCMs were characterized separately to demonstrate the operation in each mode for each structure, and tests were performed to show biosensing capability. Dual mode tests were then conducted for both the I-OQCM and PEG-OQCM, with the results showing a close correlation between the optical and mechanical responses. Finally, an OQCM array with multiple I-OQCM sensors is fabricated on a single quartz wafer and the independence among sensors is validated.