A push-pull transducer for ocean wave energy harvesting

Ocean wave energy is one of the primary energy sources, which is available during day and night, in various weather conditions. It was previously proven that energy harvesting from ocean waves could be used to generate electric power to supply sensors or small electronic devices located in buoys. Using a combination of various energy harvesters would enable more remote and unmanned future offshore sensor applications that can facilitate more effective monitoring and control. In this study, we successfully demonstrated a simple, low-cost and environmentally friendly energy harvester which can be optimally used as an Ocean Wave Energy Harvester (OWEH). Please click Additional Files below to see the full abstract

Low frequency, push-pull, electrostatic energy harvesting implementing a tunable, capacitive transducer

As devices become more integrated and advanced in their implementation, providing a source of power for these systems becomes increasingly difficult and complex. While there are many options to provide power for a limited time, maintaining or replacing these energy sources can be prohibitively dangerous, difficult, or expensive. Furthermore, as these systems decrease in size and use less power, energy harvesting systems become more viable as a means of supplying the required power, maximizing the utility of the associated technologies by allowing them to operate autonomously for extended periods or indefinitely. There exist high levels of ambient energy in the form of acoustic and mechanical vibrations that are largely untapped, primarily due to their infrasonic frequencies (< 20Hz) and the difficulties associated with developing technologies to observe them. This work presents a push-pull based, electrostatic energy harvester implementing a capacitive transducer that is easily tunable to the frequency range of interest. The realized system is capable of producing up to 250Vpp and harvesting up to 15.42uW over 60 seconds, sufficient to illuminate an LCD or LED

Soft CNT-Polymer Composites for High Pressure Sensors

Carbon&ndash;polymer composite-based pressure sensors have many attractive features, including low cost, easy integration, and facile fabrication. Previous studies on carbon&ndash;polymer composite sensors focused on very high sensitivities for low pressure ranges (10 s of kPa), which saturate quickly at higher pressures and thus are ill-suited to measure the high pressure ranges found in various applications, including those in underwater (&gt;1 atm, 101 kPa) and industrial environments. Current sensors designed for high pressure environments are often difficult to fabricate, expensive, and, similarly to their low-pressure counterparts, have a narrow sensing range. To address these issues, this work reports the design, synthesis, characterization, and analysis of high-pressure TPU-MWCNT based composite sensors, which detect pressures from 0.5 MPa (4.9 atm) to over 10 MPa (98.7 atm). In this study, the typical approach to improve sensitivity by increasing conductive additive concentration was found to decrease sensor performance at elevated pressures. It is shown that a better approach to elevated pressure sensitivity is to increase sensor response range by decreasing the MWCNT weight percentage, which improves sensing range and resolution. Such sensors can be useful for measuring high pressures in many industrial (e.g., manipulator feedback), automotive (e.g., damping elements, bushings), and underwater (e.g., depth sensors) applications

Electrostatic Acoustic Sensor with an Impedance-Matched Diaphragm Characterized for Body Sound Monitoring

Acoustic sensors are able to capture more incident energy if their acoustic impedance closely matches the acoustic impedance of the medium being probed, such as skin or wood. Controlling the acoustic impedance of polymers can be achieved by selecting materials with appropriate densities and stiffnesses as well as adding ceramic nanoparticles. This study follows a statistical methodology to examine the impact of polymer type and nanoparticle addition on the fabrication of acoustic sensors with desired acoustic impedances in the range of 1–2.2 MRayls. The proposed method using a design of experiments approach measures sensors with diaphragms of varying impedances when excited with acoustic vibrations traveling through wood, gelatin, and plastic. The sensor diaphragm is subsequently optimized for body sound monitoring, and the sensor’s improved body sound coherence and airborne noise rejection are evaluated on an acoustic phantom in simulated noise environments and compared to electronic stethoscopes with onboard noise cancellation. The impedance-matched sensor demonstrates high sensitivity to body sounds, low sensitivity to airborne sound, a frequency response comparable to two state-of-the-art electronic stethoscopes, and the ability to capture lung and heart sounds from a real subject. Due to its small size, use of flexible materials, and rejection of airborne noise, the sensor provides an improved solution for wearable body sound monitoring, as well as sensing from other mediums with acoustic impedances in the range of 1–2.2 MRayls, such as water and wood

Electrostatic Acoustic Sensor with an Impedance-Matched Diaphragm Characterized for Body Sound Monitoring

Acoustic sensors are able to capture more incident energy if their acoustic impedance closely matches the acoustic impedance of the medium being probed, such as skin or wood. Controlling the acoustic impedance of polymers can be achieved by selecting materials with appropriate densities and stiffnesses as well as adding ceramic nanoparticles. This study follows a statistical methodology to examine the impact of polymer type and nanoparticle addition on the fabrication of acoustic sensors with desired acoustic impedances in the range of 1–2.2 MRayls. The proposed method using a design of experiments approach measures sensors with diaphragms of varying impedances when excited with acoustic vibrations traveling through wood, gelatin, and plastic. The sensor diaphragm is subsequently optimized for body sound monitoring, and the sensor’s improved body sound coherence and airborne noise rejection are evaluated on an acoustic phantom in simulated noise environments and compared to electronic stethoscopes with onboard noise cancellation. The impedance-matched sensor demonstrates high sensitivity to body sounds, low sensitivity to airborne sound, a frequency response comparable to two state-of-the-art electronic stethoscopes, and the ability to capture lung and heart sounds from a real subject. Due to its small size, use of flexible materials, and rejection of airborne noise, the sensor provides an improved solution for wearable body sound monitoring, as well as sensing from other mediums with acoustic impedances in the range of 1–2.2 MRayls, such as water and wood