6,546 research outputs found

    Parylene-based electret power generators

    Get PDF
    n electret power generator is developed using a new electret made of a charged parylene HTÂź thin-film polymer. Here, parylene HTÂź is a room-temperature chemical-vapor-deposited thin-film polymer that is MEMS and CMOS compatible. With corona charge implantation, the surface charge density of parylene HTÂź is measured as high as 3.69 mC m^−2. Moreover, it is found that, with annealing at 400 °C for 1 h before charge implantation, both the long-term stability and the high-temperature reliability of the electret are improved. For the generator, a new design of the stator/rotor is also developed. The new micro electret generator does not require any sophisticated gap-controlling structure such as tethers. With the conformal coating capability of parylene HTÂź, it is also feasible to have the electret on the rotors, which is made of either a piece of metal or an insulator. The maximum power output, 17.98 ”W, is obtained at 50 Hz with an external load of 80 MΩ. For low frequencies, the generator can harvest 7.7 ”W at 10 Hz and 8.23 ”W at 20 Hz

    Micro-Contacts Testing Using a Micro-Force Sensor Compatible with Biological Systems

    Get PDF
    This paper presents the performance and reliability testing of microelectromechanical systems (MEMS) switches by using a micro-force sensor which was originally designed/used to conduct mechanical testing of biological cells. MEMS switches are key components for radio frequency (RF) applications due to their extremely low power consumption and small geometries over conventional technologies. However, unstable electrical contact resistance severely degrades the performance and reliability of such micro-switches. Therefore, our focus is to improve the performance and reliability of “cold” switched micro-contacts by using novel contact materials and engineered micro-contact surfaces. The contact metallurgies considered in this work are “similar” thin film combinations of Au, and composite Au/CNT. The non-engineered switch consists of a metallic hemispherical bump and a planar sheet as upper and lower contacts, respectively. On the other hand, the engineered switches have 2D pyramid structure in lower contacts while having a hemispherical bump at upper contact. Hemisphere on planar, Au-Au, contact pairs resulted in initial contact resistance (RC) values of ~0.1Ω (FC=200”N) that linearly increased to ~1.0Ω after ~10×106 cycles and then failed open (~10.0Ω) at ~20×106 switching cycles. The Au-Au/CNT composite, hemisphere on planar contact pair showed similar RC performance with extended reliability (~40×106 switching cycles) when the composite film was integrated into the lower planar contacted. Upper hemisphere on the 2D pyramid, Au-Au, contact pairs resulted in initial RC values of ~0.9Ω (FC=200”N) that linearly decreased to ~0.5Ω at \u3e10×106 cycles (not failed). This work suggests that the combination of engineered lower contacts and composite materials can significantly improve the performance and reliability of micro-switches

    Load Sensor in An Elastomer Suspension Element

    Get PDF
    Knowledge of the loading applied to railcar suspension elements is necessary for improved rail safety, efficiency, and for monitoring bearing health. An economical, reliable system for keeping track of both dynamic and static loads on a rail car bearing offers potential for many improvements in rail service. The difficulties of implementing such a system are considerable because the sensor must be in the bearing load path and is thus subject to all the stressors of that environment including high impact, high load, high temperature, and corrosion. This thesis describes an attempt to incorporate a load measurement system in a polyurethane suspension element. It reviews existing technology and describes several experiments using strain gauges, Micro-Electro-Mechanical pressure sensors, and piezo electric materials as load measurement devices

    Micro-manufacturing : research, technology outcomes and development issues

    Get PDF
    Besides continuing effort in developing MEMS-based manufacturing techniques, latest effort in Micro-manufacturing is also in Non-MEMS-based manufacturing. Research and technological development (RTD) in this field is encouraged by the increased demand on micro-components as well as promised development in the scaling down of the traditional macro-manufacturing processes for micro-length-scale manufacturing. This paper highlights some EU funded research activities in micro/nano-manufacturing, and gives examples of the latest development in micro-manufacturing methods/techniques, process chains, hybrid-processes, manufacturing equipment and supporting technologies/device, etc., which is followed by a summary of the achievements of the EU MASMICRO project. Finally, concluding remarks are given, which raise several issues concerning further development in micro-manufacturing

    Future of smart cardiovascular implants

    Get PDF
    Cardiovascular disease remains the leading cause of death in Western society. Recent technological advances have opened the opportunity of developing new and innovative smart stent devices that have advanced electrical properties that can improve diagnosis and even treatment of previously intractable conditions, such as central line access failure, atherosclerosis and reporting on vascular grafts for renal dialysis. Here we review the latest advances in the field of cardiovascular medical implants, providing a broad overview of the application of their use in the context of cardiovascular disease rather than an in-depth analysis of the current state of the art. We cover their powering, communication and the challenges faced in their fabrication. We focus specifically on those devices required to maintain vascular access such as ones used to treat arterial disease, a major source of heart attacks and strokes. We look forward to advances in these technologies in the future and their implementation to improve the human condition

    Real-time measurement of the three-axis contact force distribution using a flexible capacitive polymer tactile sensor

    Full text link
    In this paper, we report real-time measurement results of various contact forces exerted on a new flexible capacitive three-axis tactile sensor array based on polydimethylsiloxane (PDMS). A unit sensor consists of two thick PDMS layers with embedded copper electrodes, a spacer layer, an insulation layer and a bump layer. There are four capacitors in a unit sensor to decompose a contact force into its normal and shear components. They are separated by a wall-type spacer to improve the mechanical response time. Four capacitors are arranged in a square form. The whole sensor is an 8 _ 8 array of unit sensors and each unit sensor responds to forces in all three axes. Measurement results show that the full-scale range of detectable force is around 0–20 mN (250 kPa) for all three axes. The estimated sensitivities of a unit sensor with the current setup are 1.3, 1.2 and 1.2%/mN for the x- , y- and z -axes, respectively. A simple mechanical model has been established to calculate each axial force component from the measured capacitance value. Normal and shear force distribution images are captured from the fabricated sensor using a real-time measurement system. The mechanical response time of a unit sensor has been estimated to be less than 160 ms. The flexibility of the sensor has also been demonstrated by operating the sensor on a curved surface of 4 mm radius of curvature.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90798/1/0960-1317_21_3_035010.pd

    Microfluidics for Advanced Drug Delivery Systems.

    Get PDF
    Considerable efforts have been devoted towards developing effective drug delivery methods. Microfluidic systems, with their capability for precise handling and transport of small liquid quantities, have emerged as a promising platform for designing advanced drug delivery systems. Thus, microfluidic systems have been increasingly used for fabrication of drug carriers or direct drug delivery to a targeted tissue. In this review, the recent advances in these areas are critically reviewed and the shortcomings and opportunities are discussed. In addition, we highlight the efforts towards developing smart drug delivery platforms with integrated sensing and drug delivery components
    • 

    corecore