Detection of a carcinoembryonic antigen using aptamer-modified film bulk acoustic resonators

An AlN-based based film bulk acoustic resonator has been fabricated using a magnetron sputtering method, which was employed as a biosensor for detection of a carcinoembryonic antigen. The resonator consisted of an AlN piezoelectric layer and a Mo/Ti Bragg reflector which had a working resonance near 2.0 GHz. The carcinoembryonic antigen binding aptamers were self-assembled on the top gold electrode as the sensitive layer to capture the carcinoembryonic antigen molecules. When the sensitive layer absorbs the target molecules, the resonance frequency of the sensor decreases proportionally in response to the increase of the mass loading. The resonant frequency shifts of various carcinoembryonic antigen concentrations in the range of 0.2–1.0 mg/mL were measured. The sensor modified with the carcinoembryonic antigen binding aptamer exhibits a high sensitivity of 2284 Hz cm2/ng and Q value around 520, exhibiting a high performance. These positive results suggest that the aptamer-immobilized film bulk acoustic resonator is a promising candidate for detection of the carcinoembryonic antigen.