THE DEVELOPMENT OF A NOVEL SUSPENSION ARM WITH 2-DIMENSIONAL ACTUATION, FOR USE IN ADVANCED HARD DISK DRIVES

As magnetic computer disks are developed to ever-greater data storage densities, the accuracy required for head positioning is moving beyond the accuracy provided by present technology using single-stage voice-coil motors in hard disk drives. This thesis details work to develop a novel active suspension arm with 2-dimensional actuation for use in advanced hard disk drives. The arm developed is capable of high-bandwidth data tracking as well as precision head flying height control motion. High-bandwidth data tracking is facilitated by the use of piezoelectric stack actuator, positioned closer to the head. The suspension arm is also capable of motion in the orthogonal axis. This motion represents active flying height control to maintain the correct altitude during drive operation. To characterise the suspension arm's structural dynamics, a high-resolution measurement system based on the optical beam deflection technique has been developed. This has enabled the accurate measurement of minute end-deflections of the suspension arm in 2-dimensions, to sub-nanometre resolution above noise. The design process of the suspension arm has led into the development of novel piezoelectric-actuated arms. In the work involving lead zirconate titanate (PZT) thick films as actuators, work in this thesis shows that reinforcing the films with fibre improves the overall actuation characteristics of the thick films. This discovery benefits applications such as structural health monitoring. The final suspension arm design has been adopted because it is simple in design, easier to integrate within current hard disk drive environment and easier to fabricate in mass. Closed-loop control algorithms based on proportional, integral and derivative (PID) controller techniques have been developed and implemented to demonstrate high bandwidths that have been achieved. The suspension arm developed presents an important solution in head-positioning technology in that it offers much higher bandwidths for data tracking and flying height control; both very essential in achieving even higher data storage densities on magnetic disks at much reduced head flying heights, compared to those in existing hard disk drives

Volume 3 – Conference

We are pleased to present the conference proceedings for the 12th edition of the International Fluid Power Conference (IFK). The IFK is one of the world’s most significant scientific conferences on fluid power control technology and systems. It offers a common platform for the presentation and discussion of trends and innovations to manufacturers, users and scientists. The Chair of Fluid-Mechatronic Systems at the TU Dresden is organizing and hosting the IFK for the sixth time. Supporting hosts are the Fluid Power Association of the German Engineering Federation (VDMA), Dresdner Verein zur Förderung der Fluidtechnik e. V. (DVF) and GWT-TUD GmbH. The organization and the conference location alternates every two years between the Chair of Fluid-Mechatronic Systems in Dresden and the Institute for Fluid Power Drives and Systems in Aachen. The symposium on the first day is dedicated to presentations focused on methodology and fundamental research. The two following conference days offer a wide variety of application and technology orientated papers about the latest state of the art in fluid power. It is this combination that makes the IFK a unique and excellent forum for the exchange of academic research and industrial application experience. A simultaneously ongoing exhibition offers the possibility to get product information and to have individual talks with manufacturers. The theme of the 12th IFK is “Fluid Power – Future Technology”, covering topics that enable the development of 5G-ready, cost-efficient and demand-driven structures, as well as individual decentralized drives. Another topic is the real-time data exchange that allows the application of numerous predictive maintenance strategies, which will significantly increase the availability of fluid power systems and their elements and ensure their improved lifetime performance. We create an atmosphere for casual exchange by offering a vast frame and cultural program. This includes a get-together, a conference banquet, laboratory festivities and some physical activities such as jogging in Dresden’s old town.:Group 8: Pneumatics Group 9 | 11: Mobile applications Group 10: Special domains Group 12: Novel system architectures Group 13 | 15: Actuators & sensors Group 14: Safety & reliabilit

Self-Healing of Open-Circuit Faults in Organic Thin-Film Transistor-Based Flexible Electronics

Flexible electronics has attracted tremendous attention due to the fast-growing market for portable devices and sensors. However, these devices usually suffer from internal and external forces, which can lead to the failure of interconnects in the circuit. To address this issue, some passive and active strategies have been developed for improving the reliability of interconnects in circuits. Although all these strategies are effective in tackling problems related to the mechanical stress, they have inherent limit in dealing with other failure causes or repairing the open fault. Therefore, in this dissertation, a particle-based self-healing (PBSH) technique has been developed. The detailed study starts with an overall review of the state of the art in techniques developed for improving the reliability of interconnects in flexible circuits. Then the mechanisms of the PBSH technique are analysed and the chemical treatment of metal particles are explored. The physical modelling of the healing is established, and relations between the healing time with the suspension concentration, electric field, length of open gap, and external resistance are verified by experimental results. In addition, to avoid the inherent conductivity of the suspension and the aggregation of micro-particles, they are modified by the oleic acid. This chemical treatment of metal particles improves the uniformity of the suspension and sets a threshold electric field for the occurrence of self-healing. As a key component in flexible circuits, an organic thin-film transistor (OTFT) fabricated by all inkjet-printing process has been developed and characterised in this study. This transistor uses 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPSPentacene) as the semiconductor, poly (vinyl cinnamate) (PVC) as the dielectric, silver as the electrodes, and CYTOP as the encapsulation. Based on this device, two basic circuits: the current mirror and the common-source (CS) amplifier have been successfully built on flexible substrates. The proper functioning of the printed devices and circuits becomes the base for the study of the self-healing in flexible circuits. Subsequently, the PBSH in OTFT device and circuit interconnects is verified. This technique can successfully repair open faults at both source and drain sides in OTFT device interconnects. Simultaneously, it can heal open faults occurring at different locations in flexible current mirror and common-source amplifier circuits biased at the static state. Moreover, the self-healing is also proved to be effective and stable in common-source amplifier when processing alternating current (AC) signals. In order to demonstrate the feasibility of the PBSH technique in real-world applications, more performance characterisations have been conducted. The bending test shows the reliability and stability of the healing in the bent condition. And the dualfaults test verifies the ability of the PBSH technique for healing more than one open fault in interconnects. In addition, methods of packaging the circuit and confining the healing material in the expected region are also developed, which prove the feasibility and manufacturability of the PBSH technique in integrated circuits. This study sets a new benchmark for improving the reliability of inkjet-printed flexible circuits