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Higher modes of vibration increase mass sensitivity in nanomechanical microcantilevers

2007; IOP Publishing; Volume: 18; Issue: 44 Linguagem: Inglês

10.1088/0957-4484/18/44/445502

1361-6528

Murali Krishna Ghatkesar, V. Barwich, Thomas Braun, J.-P. Ramseyer, Christoph Gerber, Martin Hegner, H.P. Lang, Ute Drechsler, M. Despont,

Advanced MEMS and NEMS Technologies

We evaluated the potential and limitations of resonating nanomechanical microcantilevers for the detection of mass adsorption. As a test system we used mass addition of gold layers of varying thickness. Our main findings are: (1) A linear increase in mass sensitivity with the square of the mode number—a sensitivity increase of two orders of magnitude is obtained from mode 1 to mode 7 with a minimum sensitivity of 8.6 ag Hz−1 µm−2 and mass resolution of 0.43 pg at mode 7 for a 1 µm thick cantilever. (2) The quality factor increases with the mode number, thus helping to achieve a higher sensitivity. (3) The effective spring constant of the cantilever remains constant for deposition of gold layers up to at least 4% of the cantilever thickness.