Resonance Frequency Of Microcantilevers Research Articles

Gas Sensor Application of Piezoelectric Cantilever Nanobalance; Electrical Signal Read-Out

We have fabricated piezoelectric microcantilever transducer for a miniaturized gas sensor, to detect environmental gas molecules, i.e., volatile organic compound (VOC). The microcantilever consist of Pb(Zr, Ti)O 3 (PZT) capacitors and SiNx layer as an actuating and a supporting layer respectively. The fundamental resonant frequency of microcantilever was in the range of 17∼29 kHz. To measure the gas sensitivity, the microcantilever surface was coated with polymethylmetacrylate (PMMA), which is known to have sensibility for primary alcohols. The resonant frequency shift of the microcantilever was measured by complex impedance analysis, which only uses electrical signal output from the microcantilever. As the vapor concentration of the alcohol (ethanol or methanol) increased, the resonant frequency of microcantilever was linearly shifted toward the lower frequency range. The gas sensitivity of microcantilever was 0.03 Hz/ppm for methanol vapor.

Vibratory response of diamond-like amorphous carbon cantilevers under different temperatures

Diamond-like amorphous carbon films were deposited using filtered cathodic vacuum arc (FCVA) with the plasma ion immersion implantation (PIII) system. A unique multilayer film, comprising of alternating high-sp 3 content (90%), high-stress (9 GPa) films, low-sp 3 content (50%), and low-stress films (<0.5 GPa), was fabricated. By alternating these layers, a 1.5-μm-thick film was subsequently deposited. Free-standing microcantilevers measuring 150×50 μm had been subsequently fabricated by using standard lithography and wet etching. The resonance frequency of the microcantilevers was measured by a vacuum laser vibrometer system to be 109.5 kHz. After gradual heating to 240 °C, the resonance frequency was observed to increase to a high of 111.5 kHz.

Design and Analysis of Microcantilevers for Biosensing Applications

The primary deflection due to the chemical reaction between the analyte molecules and the receptor coating, which produces surface stresses on the receptor side is analyzed. The resonance frequency of microcantilevers is very sensitive to the properties of the microcantilever surface. Biosensing experiments based on resonance frequency shift are presented, which show that the results strongly depend on the interaction of specific analyte molecules with the receptor surface.

Design and Analysis of Microcantilevers for Biosensing Applications

ABSTRACTThe primary deflection due to the chemical reaction between the analyte molecules and the receptor coating, which produces surface stresses on the receptor side is analyzed. The resonance frequency of microcantilevers is very sensitive to the properties of the microcantilever surface. Biosensing experiments based on resonance frequency shift are presented, which show that the results strongly depend on the interaction of specific analyte molecules with the receptor surface.

A Self-Locking Technique With Fast Response and High Sensitivity for Micro-Cantilever Based Sensing of Analytes

AbstractMEMS based microcantilevers have been employed as sensors in both liquid and ambient conditions. One scheme for detection is based upon monitoring the change in microcantilever resonant frequency as a function of the adsorbed analyte concentration. However, the sensitivity is limited by the accuracy of the frequency measurements, which is a function of the Q-factor of the vibrating element and the measurement bandwidth. In this paper, we present a feedback scheme for self-locking amplification of the small-amplitude thermal oscillations of the microcantilever. Using this approach, we demonstrate an improvement in the Q-factor by two to three orders of magnitude as compared to that of the undriven microcantilever. Use of this technique eliminates the need for lock-in detection and results in improved response times for sensor applications. Experiments using the proposed feedback amplification technique show improved sensitivity for the detection of biological molecules in liquids, and for adsorbed vapors under ambient conditions.

Adsorption-induced surface stress and its effects on resonance frequency of microcantilevers

It is well known that bimetallic microcantilevers can exhibit static deflection as a result of thermal effects, including exothermic adsorption of chemicals on their surfaces. It is shown here that the resonance frequency of a cantilever can change due to a combination of mass loading and change of spring constant resulting from adsorption of chemicals on the surface. Cantilevers also undergo static bending that is induced by differential surface stress. The magnitude of these effects depends upon the chemical properties of the surface and upon the amount of material adsorbed. Hence cantilever deflection as well as resonance frequency change can be used as the basis for development of novel chemical sensors.