Aric Kumaran Menon

Planar Hall effect sensor for magnetic micro- and nanobead detection

Magnetic bead sensors based on the planar Hall effect in thin films of exchange-biased permalloy have been fabricated and characterized. Typical sensitivities are 3 μV/Oe mA. The sensor response to an applied magnetic field has been measured without and with coatings of commercially available 2 μm and 250 nm magnetic beads used for bioapplications (Micromer-M and Nanomag-D, Micromod, Germany). Detection of both types of beads and single bead detection of 2 μm beads is demonstrated, i.e., the technique is feasible for magnetic biosensors. Single 2 μm beads yield 300 nV signals at 10 mA and 15 Oe applied field.

Polymer-based stress sensor with integrated readout

We present a polymer-based mechanical sensor with an integrated strain sensor element. Conventionally, silicon has been used as a piezoresistive material due to its high gauge factor and thereby high sensitivity to strain changes in the sensor. By using the fact that the polymer SU-8 [1] is much softer than silicon and that a gold resistor is easily incorporated in SU-8, we have proven that a SU-8-based cantilever sensor is almost as sensitive to stress changes as the silicon piezoresistive cantilever. First, the surface stress sensing principle is discussed, from which it can be shown that the SU-8-based sensor is nearly as sensitive as the silicon based mechanical sensor. We hereafter demonstrate the chip fabrication technology of such a sensor, which includes multiple SU-8 and gold layer deposition. The SU-8-based mechanical sensor is finally characterized with respect to sensitivity, noise and device failure. The characterization shows that there is a good agreement between the expected and the obtained performance.

System-Level Modeling and Simulation of MEMS-based Sensors

The growing complexity of MEMS devices and their increased used in embedded systems (e.g., wireless integrated sensor networks) demands a disciplined approach for MEMS design as well as the development of techniques for system-level modeling of these devices so that a seamless integration with the existing embedded system design methodologies is possible. In this paper, we present a MEMS design methodology that uses VHDL-AMS based system-level model of a MEMS device as a starting point and combines the top-down and bottom-up design approaches for design, verification, and optimization. The capabilities of our proposed design methodology are illustrated through the design of a microaccelerometer

System-Level Modelling and Simulation of MEMS-Based Sensors

The growing complexity of MEMS devices and their increased used in embedded systems (e.g., wireless integrated sensor networks) demands a disciplined approach for MEMS design as well as the development of techniques for system-level modeling of these devices so that a seamless integration with the existing embedded system design methodologies is possible. In this paper, we present a MEMS design methodology that uses VHDL-AMS based system-level model of a MEMS device as a starting point and combines the top-down and bottom-up design approaches for design, verification, and optimization. The capabilities of our proposed design methodology are illustrated through the design of a microaccelerometer

Fluorocarbon Films Deposited by Deep Reactive Ion Etching for Stiction Minimization of MEMS Structures

Fluorocarbon films, which can be used to minimize stiction of silicon microstructures, have been deposited by passivation process in deep reactive ion etching tool. The wettability, surface energy, nano-scale adhesive force, and thermal stability have been investigated by contact angle measuring system, atomic force microscopy (AFM) and ellipsometry. The fluorocarbon films are good for anti-stiction applications due to their high water contact angle (110°), low surface energy (14.5mJ/m2 ), low nano-scale adhesive force (33 nN) and high thermal stability up to 300°C.Copyright

Capillary Induced Stiction and Adhesion of MEMS Materials

Adhesion and stiction are serious problems in microelectromechanical systems (MEMS) fabrication and application. The wettability, surface energies, and nano-scale adhesive forces of commonly used MEMS materials have been examined by contact angle meter and atomic force microscopy. Silicon and silicon compounds have higher surface energy than that of PMMA and SU-8 due to larger polar component of surface energy. The nano-scale adhesive forces of PMMA and SU-8 are 3–4 times smaller than that of as-received silicon with native oxide. It has been shown that the materials with higher surface energy have higher adhesive forces. One efficient way to avoid stiction in silicon microstructures is to deposit a thin fluorocarbon film coating.Copyright