Search

A pathogen detection platform that integrates electrokinetically accelerated sampling with electromechanical signal transduction is presented. Detection of pathogens without the need for cultivation is achieved by employing a prototype device that combines microelectrodes embedded directly onto the surface of a cantilever beam. Escherichia coli bacteria captured on the surface of the cantilever with the aid of AC electrokinetic effects (dielectrophoresis) within 30 min of sampling time were found to cause substantial resonant frequency shifts compared to unassisted capture. The effect of the cantilever's resonant mode was also examined in order to identify conditions that can improve detection sensitivity.

The present paper describes a novel concept that employs a thermal-based approach for in-situ displacement sensing of electro-thermal actuators. A device encompassing an in-plane electro-thermal actuator and a thermal sensor was monolithically fabricated using the MetalMUMPS process. Analytical models were developed for both the actuator and the thermal sensor. Simulation and experimental results demonstrated good agreement. The experimental results indicated that the sensor achieved high linearity and sensitivity (∼4.5 nm/Ω).

Heterodyne laser interferometry is an optical technique often used to measure displacement of surfaces along the wave vector direction of a measurement laser. For common microelectromechanical system (MEMS) testing setup, such laser wave vector is perpendicular to the substrate which the micromachined devices stand on. Therefore, this technique can only be used to characterize dynamics of the micro devices in the direction perpendicular to their substrate (out-of-plane motions) with the classic setup and it is not able to measure any motion that is parallel to the substrate (in-plane motions). In this study, in-situ micromirrors are fabricated onto a microstructure that is near the device to be measured by using a focused ion beam system. The micromirrors have a slant angle of approximate 45 degree to horizontal surface (or their substrate). By using the post-fabricated in-situ micromirror, the measurement laser of a heterodyne interferometer can be directed into horizontal plane which enables characterization of in-plane motions for micromechanical. To experimentally demonstrate the technique a micro cantilever fabricated using MetalMUMPs is used. The micro cantilever is excited by inplane electrostatic force. The results confirm the effectiveness of the method by the fact that the magnitude of the measured in-plane signal is increased by more than ten folds.Copyright © 2010 by ASME