Micro and nanomechanical resonators are highly sensitive, label-free analyte sensors in a range of environments. Resonant cantilevers, i.e. those operated in dynamic mode, can be considered as mechanical oscillators, with analyte adsorption creating a shift in cantilever resonance. Cantilever sensors work via a purely mechanical approach, transducing an analyte binding event into a nanomechanical signal. This response is governed by changes in sensor mass and stiffness due to adsorbed analytes, with previous theoretical work predicting the latter to produce significant effects on measured frequency shifts, counteracting effects of adsorbed mass. This highlights a particularly unsatisfactory feature of micro/nano-mechanical sensors, as an accurate interpretation of the sensor response must depend on both adsorbate mass and rigidity, which for nanometer-scale coverage can only be guessed, rather than derived from independent measurements. In this thesis, procedures to disentangle such effects in air and liquid are discussed and tested on a range of surface coatings, offering a novel method of analyte detection and analysis. The dynamic characteristics of cantilever beams are strongly dependent on the mass density and viscosity of the fluid in which the beams are immersed. The application of cantilevers in accurately determining such rheological properties is also presented, first via the use of model solutions, and then extending measurements to a range of commercial alcoholic and non-alcoholic drinks. A method to quantify alcohol content is also discussed, further demonstrating the commercial applications of cantilever sensors.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:677679 |
| Date | January 2013 |
| Creators | Paxman, R. |
| Publisher | University College London (University of London) |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://discovery.ucl.ac.uk/1384827/ |
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