Laterally deflectable cantilever array structures, which have potential application in sensors, displays, and optical switches for communications, have been realized by several groups. Here we demonstrate the realization of a novel nanoelectromechanical system (NEMS) device and the characterization of its performance, which is based on a laterally deflectable cantilever array structure. We will also discuss its different applications.
The structure of our NEMS device is a laterally deflectable double-finger interdigitated cantilever array, which is made on SiO2/Si substrate covered by a thin metal layer. The pattern of the device could be fabricated by either nanoimprint lithography or electron beam lithography. Using the pattern as etching mask, free standing cantilevers are obtained by isotropic and anisotropic reactive ion etching. In the final step, a metal layer is evaporated onto the structures. When a bias voltage is applied to the device, the cantilevers will bend to each other due to the electrostatic force.
By applying a DC voltage and an AC voltage with variable frequency, the deflection and oscillating behaviors of the cantilevers are studied under an optical microscope. The movement of the cantilevers is displayed as the intensity variations of the diffraction pattern by measuring it with a digital camera or a photodiode. The results show that the device can be used as an optical switch or an accelerometer, just to mention a few possible applications. The resonance frequency of the cantilever arrays was also determined. In addition, the absorption of CH3(CH2)11SH on the Au-coated cantilevers, induced a shift of the resonance frequency by 25 kHz. This result indicates that the device has a high potential as a mass sensing device.
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