| One of the most important applications for cantilever-based sensors is the detection of specific binding of biomolecules. This work aimed at developing of a cantilever-based mass sensor capable of detecting specific binding of biomolecules. A comparison between the dynamic and the static operation modes of the cantilever sensor was presented and the dynamic operation was selected for the quantitative measurement of mass change-induced resonance frequency shift. Simulations were carried out to determine the dimensions of the devices, to predict the relationship between the frequency shift and the mass change, and to resolve problems in the fabrication before the cantilever arrays were actually produced, including the stress-induced deformation. Sulfo-LC-SPDP, a chemical linker for bioimmobilization, was employed to introduce a common protein antigen onto the sensor surface through the thiol-Au coupling. This antigen was later used for the recognition of the corresponding antibodies in samples. Various optical readout mechanisms were used for measurements of effective mass change-induced frequency shift and the laser Doppler vibrometry was selected as the optimal method because of its excellent Q-factor and relatively simple setup. A linear relationship between the resonance frequency shift ratio and the amount of effective mass change was observed within a 10-40 pg measurement range. It was determined that this method, as presently applied with our antibody-antigen pair, had a detection resolution of 9.6 pg and a saturation threshold of 40 pg. This provided the proof of concept for the utilization of this type of sensor in clinical applications. |
