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Microscope image depicting the sensor with labeled shuttle mass SM, microbeam sensors , , , and , and detection laser location L. The inset depicts the capillary tube method used to functionalize the microbeam sensors.
The frequency response of the device obtained experimentally by base exciting it with band-limited white noise and sensing the shuttle mass motion with the laser vibrometer in vacuum. The mode shapes, obtained experimentally using a Polytec scanning laser vibrometer, at resonances , , , , and , are also depicted.
The resonance frequency shift of the localized microbeam modes vs concentration of toluene (left) and methanol (right). Note that the analyte concentration is given by . Also note that in this figure, and in Fig. 4, the device was excited with a swept sine wave. Band-limited white noise excitation yielded similar results.
The resonance frequency shift of the localized microbeam modes , which are labeled 1–4, respectively, due to the presence of (a) 2.9% toluene, (b) 3.9% methanol, and (c) a mixture of 2.3% methanol and 2.3% toluene. (d) Close-up of the downward resonance shift in the shuttle mass response near comparing pure nitrogen and 5.8% methanol environments.
Polymers and solvents used for microbeam functionalization. Solution concentrations shown as mg polymer per mL solvent.
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