|AVS 54th International Symposium|
|MEMS and NEMS||Tuesday Sessions|
|Session:||MEMS and NEMS Poster Session|
|Presenter:||K. Lukes, University of California, Santa Barbara|
|Authors:||K. Lukes, University of California, Santa Barbara
K.L. Turner, University of California, Santa Barbara
J. Rhoads, Michigan State University
S. Shaw, Michigan State University
|Correspondent:||Click to Email|
This work presents a novel implementation of mechanical domain, parametric amplification in electromagnetic microcantilevers. Parametric amplification is the amplification of a signal due to pumping energy into the system parametrically. This class of resonators shows great potential for implementation as chemical sensors, since they exploit the induced electromotive force (emf) for sensing1 giving potential for complete onchip integration. It is difficult to recover the sense signal because it is several orders of magnitude smaller than the drive signal. Parametric amplification offers low noise gain for signal recovery. We describe the model and experimental validation of parametric amplification. A measure of merit for the amplifier is its gain. Gain is defined as the ratio of sensor’s amplified to harmonic response. Analysis of the gain function shows the response is amplified asymptotically as the pump approaches the limiting magnitude defined by the onset of parametric resonance, and depends on the square root of sin(2φ), where φ is the phase shift between the input signals. Parametric amplification is achieved by the microcantilevers. Each cantilever has metal wires deposited on the surface, making it a closed current loop. The device sits on an angled permanent magnet. An AC current, consisting of the sum of the harmonic and parametric signals, passes through the device producing the Lorentz force. The force can be broken into a normal component, the harmonic forcing, and axial component, the parametric pump. The dynamics of the resonators are measured using a single point laser vibrometer in vacuum.2 These devices have shown the capability for emf sensing;1 vibrometry is used for proof of concept. Experimental data confirms the expected relationship of gain to φ and pump magnitude. We have successfully shown parametric amplification in electromagnetically actuated microcantilevers. Theoretical results anticipate large gains and experimental data confirms that these gains are feasible. The ability to mechanically amplify the signal of the transducer shows potential for a complete on-chip chemical sensor.
1 Requa, M.V. and K.L. Turner. APL, 2006. 88(26)
2 Turner, K., Hartwell, P., MacDonald, N. in 10th International Conference of Solid-State Sensors and Actuators (Transducers 1999). 1999.