4M Knowledge base - papers

J. Matović(a), Z. Jakšić(b)
a: ISAS, Technical University, 1040, Vienna, Austria
b: IHTM, University of Belgrade, 11000, Belgrade, Serbia

Abstract

We present a novel simple and efficient method for the full removal of the influence of ambient temperature variations to the operation of bimaterial-based MEMS actuators and sensors. The removal of the undesired interference is achieved through the very structure of the bimaterial cantilever, by reversing the order of bimaterial constituent materials at a certain length. Thus an extremely simple geometry is obtained for full self-compensation of the structures. We performed the full simulation of our devices by the finite element method. The structures require standard surface micromachining and utilize only Si-technology compatible materials like polyimides or SU-8. A simple rule for the determination of the zero-deflection condition is presented. The described compensation method enables a significantly reduced bimaterial device area and a much higher packaging density in element arrays, as well as an improved signal-to-noise ratio. The method is especially convenient for photodetector arrays for direct conversion of infrared radiation spatial distribution into a visible image.

G. Todorov, K. Kamberov, and L. Dimitrov
CAD/CAM/CAE Laboratory, Technical University of Sofia, Sofia 1000, Bulgaria

Abstract

MEMS actuators are widely used in modern industry. Their main advantage is the concentration of desired mechanical characteristics in a limited space. This paper presents a design and optimization of a flat solid MEMS actuator. The optimization is based of the selection of material properties needed for the achievement of the actuator mechanical characteristics required for good performance. The main goal is to reach necessary output mechanical force with minimal side force effects. The output mechanical force is evaluated by modeling and simulation of the magnetic field and its parameters by the use of FE Analyses. In order to make proper simulations, a finite element model of the complete actuator structure is made up suggested).

Another problem that has been solved in the paper is checking of actuator’s geometry and its dimensions in order to evaluate the effective use of the material. As a result of the study, the optimal output function of the mechanical force versus the stage position has been determined. This has been done on the basis of updated material specifications. The optimal design of a flat solenoid MEMS actuator is proposed.

R. Voicu, D. Esinenco, R. Müller, L. Eftime, C. Tibeica
National Institute for Research and Development in Microtechnologies – IMT Bucharest, 126A, Erou Iancu Nicolae Street, Bucharest, Romania

Abstract

Thermal microactuators are based on the principle of material deformation due to heat generated by Joule effect. As a class of microactuators, the microgrippers are promising tools for manipulation of micro and nano - scaled objects. The designs of two models of SU-8 microgrippers electro-thermally actuated are described. A simple design for an electro-thermaly actuated polymeric microgripper is compared with an improved design using a pair of heaters on both sides of the microgripper. We demonstrated that it is possible to reduce the unwanted out of plane displacement, the second model capable of being more stable to the out of plane deflection, generated by the stress, when a voltage is applied. Electro-thermo-mechanical simulations based on finite element method were performed for each of the model in order to make a comparison between the results. Preliminary results on the fabrication of the last model, using a surface micromachining technique and an SU-8 polymer as functional material are presented.

V.Stavrov(a), P.Vitanov(b), E.Tomerov(a), E.Goranova(b), G.Stavreva(a)
a: Nano ToolShop Ltd., Microelectronica Industrial Zone, 2140 Botevgrad, Bulgaria
b: Central Laboratory of Solar Energy and New Energy Sources, Bulgarian Academy of Sciences, 72”Tzarigradsko chaussee”, blvd, 1784 Sofia, Bulgaria

Abstract

Future of analytical and manufacturing methods based on micro-mechanical cantilevers, depends critically on the ability to implement parallel operation and fast signal processing [1]. There are two mean reasons: high throughput requirement and complexity (multidimensionality) of analyzed value. In order to get parallel function, any single device should be simultaneously: recognizable, autonomously actuated and independently accessible for readout. Devices, fulfilling these requirements, are suffering from a substantial increase in complexity of both layout and manufacturing technology. In present paper, we demonstrate a novel design of a MEMS (Micro-Electro-Mechanical Systems) cell designed for e-NOSE applications, using results of previous works [2,3], which solves above mentioned problems.

The cell consists of four integrated cantilevers, each having a separate piezoresistor. Additionally, the cantilevers are designed to be different in length and thus having different resonance frequencies. Thus, individual cantilevers are frequency recognizable/addressable. Samples of self-actuated piezoresistive cantilever sensor have been fabricated on n-type, silicon, applying combined surface and bulk micromachining techniques. The cantilever dimensions were chosen to provide approx. 1.8 kHz resonance frequency gap between neighbor individual sensors. The new micro-machined cell is suitable for chemical and biological recognition as a micro-balance.

S. G. Serra(a), Z. Rozynek(b), A. Almansa(b), V. Djakov(a), A. Schneider(a), S. E. Huq(a), I. Montealegre(b), P. Castillo(b), S. Bou(b)
a: Science and Technology Facilities Council, Rutherford Appleton Laboratory (RAL), Technology – Central Microstructure Facility, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0QX, UK
b: Profactor Research and Solutions GmbH, 2444 Seibersdorf, Austria

Abstract

This paper describes the first steps for the fabrication of low-cost cantilever arrays, developed at RAL, on nonsilicon polymer substrates with vertical interconnects, produced at Profactor. The deflection and actuation of these cantilevers is based on the bimorph thermal actuation principle. The fabrication of the cantilever arrays requires many process steps which are presented in this article. The first one is the planarization between the via-holes interconnects with a uniform layer. This was achieved by spin coating of a thick (~58μm) SU-8 layer. Next, two thin metal layers of Cr (500Ǻ) and Au (1000Ǻ) were thermally deposited and patterned, using UV lithography with a mask alignment process and wet etching. The following step was the coating of a 1μm structural Au layer, in which the deposited layer had a very poor adhesion. Alternative procedures were explored to overcome this problem in the future. Modifications of the photo masks design and the substrates will be carried out to make the RAL microcantilevers technology more compatible with Profactor substrates.