Systems: Novel Product and Process Designs

Ultrasonic Plasticising for Micro Injection Moulding

W. Michaeli, D. Opfermann
Institute of Plastics Processing at RWTH Aachen University, 52056 Aachen, Germany

Abstract

Ultrasonic energy is already used in the field of polymer welding. Research conducted at IKV shows a potential to use ultrasonic plasticising to generate melt for micro injection moulding. A test unit has been built to prove its potential as a plasticising unit. Based on these results the ultrasonic plasticising has been integrated into the micro injection moulding process. This leads to a significant reduction of the cycle time. Further research will focus on determining processing parameters for different materials and to further optimise the equipment.

Keywords: micro injection moulding, plasticising, ultrasonics, melting

The micro-machining evaluation of non-metallic materials - by a fluid guided laser

Paul C. Snowdon a, David Wood a, Paul G. Maropoulos b
a School of Engineering, Durham University, South Road, Durham, DH1 3LE, UK
b Department of Mechanical Engineering, University of Bath, Bath, BA2 7AY, UK

Abstract

The waterjet-guided laser technique was originally developed to reduce the heat-affected zone near the cut, but many other advantages were observed due to the use of a waterjet rather than an assist-gas stream applied in classical laser cutting. This paper reports on the application of a fluid guided laser system, as an agile tool for the micro-machining of MEMS substrates, and materials associated with the expanding MEMS industry. An increasing number of applications require a more superior machining quality than can be achieved using standard/classical laser cutting. The materials machined during these evaluations include, gallium arsenide (GaAs) & silicon wafers, ceramic packaging (alumina) and kapton. An Nd:YAG laser operating at 1064 nm (infra red) and frequency doubled 532 nm (green) was employed for the machining of the various non-metallic materials.

Keywords: Fluid guided laser, Laser Microjet®, MEMS, micro-machining

Low Cost Capacitive Inclination Sensors based on selectively metallized polymer

Benz Daniel a; Botzelmann Tim b; Kück Heinz a,b;Warkentin Daniel b
a Institut für Zeitmesstechnik, Fein- und Mikrotechnik, Universität Stuttgart, Breitscheidstr. 2b, 70174 Stuttgart, Germany
b Hahn-Schickard-Gesellschaft, Institut für Mikroaufbautechnik, Breitscheidstr. 2b, 70174 Stuttgart, Germany
email: benz@izfm.uni-stuttgart.de, Phone:++49 711 121 3706, Fax: ++49 711 121 3705

Abstract

We report on an innovative low cost concept for micromechanical capacitive inclination sensors based on MIDtechnology (Moulded Interconnect Device) where three dimensional polymer devices are fabricated by injection moulding and covered by a structured metal layer using electroless plating and laser ablation. The sensor concept based upon an extended electrode design which combines two differential capacitors arrangements for a measurement range of ±180°. First MID-demonstrators were fabricated and characterized. The demonstrators show very promising properties. The sensors have a nice linear characteristic within ±45° and 45°-135° with a resolution of about 0,01° and a nonlinearity better than 0.5% FSO. At different angular rates a dynamical hysteresis occurs. The dynamical hysteresis is proportional to the rotational speed of the sensor. The temperature dependence is very low and almost linear. No failure occurred within first reliability tests of 100 sensors with thermal shock test and constant damp heat storage.

Keywords: inclination sensor, moulded interconnect device, non-silicon material

High resolution low cost optical angular resolver

V. Mayer, D. Warkentin, H. Kück
Hahn-Schickard-Gesellschaft, Institute for Micro Assembly Technology, Breitscheidstr. 2b, 70174 Stuttgart, Germany

Abstract

At HSG-IMAT a new concept for a high resolution and low cost optical angular resolver is developed. The key element of the sensor concept is a disc with a high precision solid measure which is fabricated using the well known manufacturing process for compact discs (CD-Technology). Using this process, it is possible to fabricate a high precision solid measure in high quantities and at low manufacturing costs. To detect the angular position, a laser beam is focussed onto the solid measure. The beam is reflected from the backside of the disc onto a photo diode. The light intensity is modulated by diffractive microstructures of the solid measure. With a first experimental setup, the functional principle of the sensor was verified and the signal modulation with high accuracy was demonstrated. With a 10μm laser spot on the disc, diffractive microstructures with a width of 10μm (equivalent to 20μm pitch) are easy to detect. The experiments show that even fields smaller than 6μm can be detected with the setup. Incremental and absolute encoded systems can be realised with the sensor concept. For serial production of the sensor a 3D packaging in MID-Technology is proposed.

angular resolver, rotary encoder, optical sensor, low cost, compact disc, laser

Micro EDM: Accuracy of on-the-machine dressed electrodes

A. Rees a, S.S. Dimov a, A. Ivanov a, A. Herrero b and L.G. Uriarte b
a Manufacturing Engineering Centre, Cardiff University, CF24 3AA, U.K.
b Tekniker, Avda, Otaola 20, 20600 Eibar, Spain

Abstract

The introduction of a technique for on-the-machine electrode generation, utilising Wire Electrode Discharge Grinding (WEDG) has broadened the application area of the μEDM process. This paper studies the capabilities of the WEDG process for manufacturing micro electrodes. The accuracy of the electrodes produced on-the-machine is investigated and a solution is proposed to improve the process. The experimental results revealed the inherent limitations of the WEDG dressing process and the effects of machine accuracy on electrode quality. The study shows that by employing an optical verification system the accuracy of the dressing process could be improved significantly.

Keywords: Micro EDM, micro-machining, EDM accuracy, WEDG, electrode dressing

All Polymer Electrochemical Sensor

M.Bengtsson 1, G.Thrastardottir 1, T.S.Hansen 2, O.Geschke 1
1 Department for Micro- and Nanotechnology, Technical University of Denmark, 2800 Kongens Lyngby, DK
2 Department of Chemical Engineering, Technical University of Denmark, 2800 Kongens Lyngby, DK Danish Polymer Centre

Abstract

The paper describes the development of an all polymer electrochemical sensor in poly(3,4-ethylendioxythiophene) (PEDT) for detection of hydrogen peroxide (H2O2). To increase the sensitivity of PEDT to H2O2 Prussian blue (PB) has been added to the polymer to act as an catalyst for reduction of H2O2 . The sensitivity of the sensor with this addition was shown to increase up to 4 times. In order to use the sensor in a miniaturized flow format a flow cell was designed and tested with the same setup of polymer electrodes.

Keywords: conductive polymers, electrochemical sensors, PEDT

A Novel Protective Cover for Microcomponents

Aleksandra Cvetanovic, Andreja Cvetanovic, Daniela Andrijasevic, Ioanna Gioroudi, Werner Brenner
Vienna University of Technology, Institute of Sensor and Actuator Systems, Floragasse 7/ 2, 1040 Vienna, Austria

Abstract

This paper presents a novel tool for assembly of micro particles in a SEM chamber. A new mechanismus, called Protective Cover for Microcomponents, which allows the positioning of the micro parts on the platform inside the chamber without gluing them on the platform is proposed. It is well known the vacuum pump, especially turbo pump, that makes a vacuum in the SEM chamber, has higher sensitivity to foreign object damage. That is the reason why the micro parts are glued on the disks in the platform of the SEM chamber. Otherwise, the grippers that have to pick, to lift and place the particle in a desired system (position, orientation) are very fragile and can not overcome the adhesive force of glue and separating the particle from the disk. Besides, for the automated assembly process it is very important that the particles stay on the exactly defined location and position. The showed system is standard and can be mounted without additional time, modification or expenses into the SEM chamber. It enables, on the one hand, easier manipulation of the micro parts, that need not to glue on the base and, on the other hand, opens the door for introduction more automation in the manipulation process in the SEM chamber by making a basis for modular assembly system. Therefore the future constructing of a modular holder which can correspond to different requirements of the assembly of numerous microsystems will also be reported .Need for standardisation in micro world becomes more and more articulate. With a higher level of standardisation, the degree of automation grows up, too. The uniformity of parts, operations and tools is a strong support to an automation assembly system.

Keywords: micro assembly, SEM, micromanipulation

Micro injection moulding: the effects of tool surface finish on melt flow behaviour

C.A. Griffiths, S.S. Dimov and D.T. Pham
Manufacturing Engineering Centre, Cardiff University, Cardiff CF25 3AA, UK

Abstract

Micro-injection moulding is one of the key technologies for micro-manufacture and is widely used as a cost effective replication method for mass production. The capabilities of this replication technology have to be studied systematically in order to determine the process constraints. In this research, the factors affecting the flow behavior are discussed and special attention is paid to the interaction between the melt flow and the tool surface. Three different polymer materials, PP, ABS and PC, were utilised to perform moulding tests using cavities with the same geometry but different surface finish. Through a series of experiments the effects of the tool surface finish on the melt flow length and part quality were investigated by varying three process parameters, melt and mould temperature, and injection speed.

Keywords: micro-injection moulding, part quality, surface finish.

Polymer optical micro-array sensor

P.J. Bolt a, R. de Zwart a, R. Houben a, G. van Heck a, F. Dennard a, P. Rensing a, J. van Veen b, B. Langeveld c, M. Koetse c, H. Schoo c *

a TNO Science & Industry, P.O. Box 6235, 5600 HE Eindhoven, The Netherlands
b TNO Quality of Life, P.O. Box 360, 3700 AJ Zeist, The Netherlands
c Holst Centre, High Tech Campus 48, 5656 AE Eindhoven, The Netherlands
* corresponding author herman.schoo@tno.nl

Abstract

All-polymer sensors made by mass-production techniques are feasible due to the development of opto-electronic polymers. Using these materials, it is possible to put sensor and electronic functions on a foil by printing techniques, allowing sensors to be mass produced at low cost. However, before this will be reality, many steps have to be made. This paper describes one of these, namely the development of a demonstrator to show the feasibility of an optical micro-array sensor. Such a sensor comprises matrices of both organic light emitting and light responsive devices, which can be fine tuned with respect to their spectral response. This allows a large freedom for making sensors for different applications. The lay-out of the matrices with organic devices, the interlayer with active sensor materials, jetting of these materials on an interlayer and the interlayer itself will be presented. Future steps will be discussed.

Keywords: optical sensor, opto-electronic polymers, reel-to-reel, printing

Design and testing of a d31 mode piezoelectric unimorph for direct power generation by coupling with a microcombustor

G. Liu a, R.W. Whatmorea b
a Nanotechnology Centre in the Department of Materials, Cranfield University, Beds, MK43 0AL, UK
b Present address: Tyndall National Institute, 'Lee Maltings', Cork, Ireland

Abstract

The design and testing of a piezoelectric unimorph disk for electric power generation is discussed. The motivation for the work is the increasing demand for extended life power supplies for use in portable electronic devices such as laptops and remote surveillance systems. The unimorph comprises a piezoelectric ceramic bonded onto a steel disk, operating in d31 radial mode so that lateral stresses cause a charge difference through the thickness of the unimorph. The charge can then be extracted and conditioned to do useful work. This article highlights the design and the testing of the unimorph for two loading conditions. Firstly to apply a uniformly distributed pressure pulse to the underside of the disk using compressed air. Secondly to couple the unimorph to a 5mm3 combustion chamber, this burns a stoichiometric mixture of hydrogen and oxygen. The overall pressure change due to the compressed air or combustion causes the unimorph to deflect up to
50m and become stressed, in doing so generating electrical charge through the piezoelectric effect. Testing has shown that milli-Watts of power can be generated with this configuration of piezoelectric unimorph, found through the power dissipation across a known load.

Keywords: piezoelectric, d31, unimorph, flexure, power generator, microcombustor

Water jet machining of MEDM tools

O. Blatnik a, H. Orbanic a, C. Masclet b, H. Paris b, M. Museau b, J. Valentincic a, B. Jurisevic a and M. Junkar a

a University of Ljubljana, Slovenia
b University of Grenoble, France

Abstract

This contribution presents an investigation about the possibilities of using Water Jet (WJ) technology in combination with Micro Electrical Discharge Machining (MEDM) for tooling production in micro manufacturing. In the first phase the tool copper used in MEDM is produced by WJ machining. Afterwards, the final tool in steel is produced by MEDM. Such kinds of tools intend to be used in processes like hot embossing, molding, and other replication technologies in the field of micro manufacturing. The first results are very promising and the proposed tooling strategy, which involves besides MEDM also WJ technology, shows a lot of potential especially in the design and developing phase of micro-fluidic devices.

Keywords: tooling, non-conventional technologies, MEDM, WJ, micro-fluidics

Sensor-less measurement of rotational speed for piezoelectric micro-motors

A. Venturi and S. A. Wilson
Materials Department, School of Industrial and Manufacturing Science, Cranfield University, Cranfield, Bedfordshire, MK43 0AL United Kingdom

Abstract:

Accurate measurement of speed, acceleration, blocking force and torque for actuators on the micro-scale is problematic by conventional means. Forces tend to be very low and time-scales relatively short. This paper describes experimental research on a non-contact technique that can be used to measure the performance of an ultrasonic piezoelectric micro-motor. A type of sensor-less speed measurement has been achieved by studying the frequency spectrum of the real power absorbed by two different motors. This shows a characteristic spike at low frequencies corresponding to the equilibrium rotational speed. The origin of this low frequency modulation is dependent on the impedance of the motors and the applied mechanical loads.

Keywords: Speed measurement; PZT; micro-motor; real power, flextensional

Flow control for high-pressure micro hydraulics

A.J.M. Moers, D. Reynaerts
Department of Mechanical Engineering, Faculty of Engineering, Katholieke Universiteit Leuven
Celestijnenlaan 300B B-3001 Heverlee, Belgium

Abstract

In order to achieve a high force density in microsystems, hydraulics can be used. In our current research, these actuators are used to control surgical instruments inside the human body. For this kind of hydraulic microrobots, flow rates of 100 mm3.s-1 at a supply pressure of 10 bar need to be controlled. Hydraulic valves will be incorporated into the system near the actuators. Existing valves do not meet the specifications. Conventional hydraulic systems are too large because the dimensions are not a critical design factor. They are developed for much higher flow rates and much higher supply pressure. Existing valves for micro hydraulic systems are designed to control low flow rates at low pressure. They are for instance suitable for lab on chip technology [1]. This paper describes the ongoing research on micro valves which is a part of the micro-hydraulics and micro-robotics research at the Micro and Precision Group of K.U.Leuven.

Keywords: micro hydraulics, high force and high power density micro-systems, system integration