| This work presents a label-free bio-molecular detection technique based on real-time monitoring of the resonant frequency of micromechanical thermal-piezoresistive rotational mode disk resonators encapsulated in microfluidic channels. Mass loading via adsorption of molecular layers on the surface of such devices results in a frequency shift. In order to provide a reliable platform for sample-resonator interactions and to protect the resonators from contaminants, the resonators were encapsulated in PDMS-based micro-fluidic channels. Micro-channel encapsulation also allows insulation of electrical signals from the analyte solution. To characterize the performance of such devices as real-time label-free bio-molecular detectors, the strong non-covalent binding of Avidin with its ligand, biotin was utilized. To further validate the measured frequency shifts and confirm that the frequency shifts are due to molecular attachments to the resonator surfaces, fluorescent labeled molecules followed by fluorescent imaging was used confirming the existence of the expected molecular layers on the resonator surfaces. |
