Microcantilever Spectroscopy: Experimental Parameter Estimation through Near-Surface Hydrodynamics, and Label-Free Mass Sensing via Nodal-Line Manipulation
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Authors
Jalil, Md Tasmirul
Issue Date
2025
Type
Dissertation
Language
en_US
Keywords
Alternative Title
Abstract
This dissertation investigates two particular avenues of micantilever-based nanometrology. First, it focuses on the estimation of the experimental parameters associated with Atomic Force Microscopy (AFM) in liquid environment. When an AFM microcantilever is operated at close proximity to a surface in a liquid environment, the hydrodynamic forces influence its dynamic behavior significantly. Specifically, its resonance frequency and quality factor become sensitive to the proximity parameters such as the tip–sample gap height and the tilt angle of the cantilever relative to the substrate. By developing robust numerical and experimental methodologies to exploit the dynamic behavior of the microcantilever, this research demonstrates that the proximity parameters of the microcantilever can be estimated with reasonable accuracy, thereby opening a pathway toward quantitative, resonance-based calibration of cantilever geometry in fluidic AFM applications. Secondly, the dissertation emphasizes exploring the capability of microcantilever-based label-free mass spectroscopy techniques. Unlike conventional mass spectrometry, a microcantilever resonator can directly weigh ultralight chemical and biological analytes in real time. However, due to the fixed geometry of these structures, attachment of these ultralight analytes to the beam structure is restricted to the location on the beam where the modal response is substantial. Therefore, detection of multiple analytes using a single microcantilever beam is problematic and requires extensive effort to overcome the crosstalk in the detection process. Addressing this limitation, a microcantilever plate structure is proposed, and it is established that by actively manipulating the nodal lines of the plate’s vibration modes, it is possible to shift the sensitive regions of the resonator, enabling detection of ultralight analytes at multiple locations on a single device. This strategy not only mitigates the single-position limitation of traditional cantilever beams but also opens up new possibilities for high-throughput and multi-site mass spectroscopy beyond the micro- and nanoscale, enhancing the versatility and impact of cantilever-based sensors in biological and chemical analysis.