High-sensitivity mass and position detection of micro-objects adhered to microcantilevers

A dynamic method for mass detection, considering attaching positions of micro-objects on microcantilevers, is introduced. Two models based on the Rayleigh– Ritz method were developed for analyses of the first flexural and the first torsional modes of a “cantilever– mass” system, respectively. Due to one-to-one correspondence between the longitudinal adhering positions of the micro-objects and the flexural resonant frequencies of the “cantilever–mass” system, the first model was employed for high-sensitivity mass detections of multi-object with different attaching positions on the cantilevers. The second model was developed for the analyses of links between the first torsional frequency of the “cantilever–mass” system and the transverse attaching positions of the micro-objects. Uniting these two models, the longitudinal and transverse attaching positions of one micro-object can be determined. Experimental results of polystyrene microspheres and ambrosia pollens attached on the microcantilever in the air validated the setup of the analytical models.