More than a decade of research in the field of thermal, motion, vibration and electromagnetic radiation energy harvesting has yielded increasing power output and smaller embodiments. Power management circuits for rectification and DC-DC conversion are becoming able to efficiently convert the power from these energy harvesters. This paper summarizes recent energy harvesting results and their power management circuits.

Micropower energy harvesting

The electrospinning process was used successfully to fabricate nanofibers of poly(ethylene oxide) (PEO) in which multiwalled carbon nanotubes (MWCNT) are embedded. Initial dispersion of MWCNTs in water was achieved using amphiphiles, either as small molecules (sodium dodecyl sulfate, SDS) or as a high molecular weight, highly branched polymer (Gum Arabic). These dispersions provided separation of the MWCNTs and their individual incorporation into the PEO nanofibers by subsequent electrospinning. The focus of this work is on the development of axial orientations in these multicomponent nanofibers. A theoretical model is presented for the behavior of rodlike particles representing CNTs in electrospinning. Initially the rods are randomly oriented, but due to the sinklike flow in a wedge they are gradually oriented mainly along the stream lines, so that straight CNTs are almost oriented upon entering the electrospun jet. The degrees of orientation of polymer, surfactant, and MWCNT were studied using X-ray dif...

Carbon Nanotubes Embedded in Oriented Polymer Nanofibers by Electrospinning

Recent advance and prospectives of electrocatalysts based on transition metal selenides for efficient water splitting

This review surveys micromachined gyroscope structure and circuitry technology The principle of micromachined gyroscopes is first introduced Then, different kinds of MEMS gyroscope structures, materials and fabrication technologies are illustrated Micromachined gyroscopes are mainly categorized into micromachined vibrating gyroscopes (MVGs), piezoelectric vibrating gyroscopes (PVGs), surface acoustic wave (SAW) gyroscopes, bulk acoustic wave (BAW) gyroscopes, micromachined electrostatically suspended gyroscopes (MESGs), magnetically suspended gyroscopes (MSGs), micro fiber optic gyroscopes (MFOGs), micro fluid gyroscopes (MFGs), micro atom gyroscopes (MAGs), and special micromachined gyroscopes Next, the control electronics of micromachined gyroscopes are analyzed The control circuits are categorized into typical circuitry and special circuitry technologies The typical circuitry technologies include typical analog circuitry and digital circuitry, while the special circuitry consists of sigma delta, mode matching, temperature/quadrature compensation and novel special technologies Finally, the characteristics of various typical gyroscopes and their development tendency are discussed and investigated in detail

The Development of Micromachined Gyroscope Structure and Circuitry Technology

Fabrication of transition metal selenides and their applications in energy storage

In this paper a detailed modeling, simulations and testing of a novel electrostatically actuated microgripper integrated with capacitive contact sensor is presented. Microgripper is actuated with lateral comb drive system and transverse comb system is used to sense contact between micro-object and microgripper jaws. The design is optimized in standard SOI-MUMPs micromachining process using L-Edit of MEMS-Pro. Finite element analysis of microgripper is performed in COVENTOR-WARE which shows total displacement of 15.5 μm at the tip of jaws when voltage of 50 Vdc is applied at the actuator. Finite element analysis of sensor part is performed and results are compared with analytical model. Modal analysis is performed to investigate mode shapes and natural frequencies of the microgripper. Microgripper is tested experimentally and total displacement of 17 μm is achieved at the tip of microgripper. The slight difference between finite element analysis and experimental results is due to small variations in the material properties, deposited during the fabrication process. The change in capacitance of capacitive contact sensor is linearly calibrated with the change in the displacement. The sensitivity of contact sensor is 90 fF/μm. The total size of microgripper is 5.03 mm × 6.5 mm.

Design, simulation and testing of electrostatic SOI MUMPs based microgripper integrated with capacitive contact sensor

We report the successful synthesis of polycrystalline CdO nanomaterials at various process temperatures in the range from (180°C - 300°C) by a single step, conventionally simple and cost effective approach The approach is based on hydroxide melts as solvents and termed as composite-hydroxide-mediated (CHM) approach The effect of growth temperature on particle nucleation and consequently on the fabrication and purity of CdO nanostructures is investigated for a constant reaction time (24 h) As revealed by x-ray diffraction and Raman spectroscopy, CdO nanostructures can be reproduced in high purity with no traces by varying the synthesis temperature These nanostructures have random orientations and non-uniform distribution with average crystallite sizes varying from 27 nm down to 7 nm A study of the optical properties, based on photoluminescence, has demonstrated that emission peaks of CdO nanomaterials are centered at 491 nm and 528 nm which signifies purity of the product from the CHM approach The direct bandgap determined for CdO (249 eV - 251 eV) exhibits a blue-shift with process temperature The photoluminescence peak at 491 nm is attributed to near band-edge emission Based on experimental results size and morphology manipulation, and possible growth mechanisms for the synthesized product are proposed with CHM at low temperature and without surfactant
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Optoelectronic properties and temperature dependent mechanisms of composite-hydroxide-mediated approach for the synthesis of CdO nanomaterials

This paper reports the design implementation of three degree-of-freedom (3-DoF) non-resonant MEMS gyroscope having 2-DoF drive-mode oscillator. The proposed architecture utilizes structurally decoupled active-passive mass configuration to achieve dynamic amplification of oscillation in 2-DoF drive-mode. This results in higher sensitivity and eliminates the need of mode matching for resonance. A low cost standard Metal-Multi User MEMS Processes (MetalMUMPs) is used to fabricate 20 μm thick nickel based gyroscope with an overall reduced size of 2.2 mm × 2.6 mm. The experimental characterization demonstrated that the frequency response of the 2-DoF drive-mode oscillator has two resonant peaks at 754 Hz and 2.170 kHz with a flat operational region of 1.4 kHz between the peaks. The sense-mode resonant frequency lies at 1.868 kHz within this flat operational region where gain is less sensitive to structural parameters and environmental variations. This results in improved robustness to fabrication imperfections and environmental variations and long term stability without utilizing tuning and feedback control. Gyroscope dynamics and system level simulations using behavioral modeling are carried out to predict the performance of the device. Experimental results show close agreement with the behavioral simulation results due to incorporation of improved damping models in behavioral model developed in CoventorWare.

Design, damping estimation and experimental characterization of decoupled 3-DoF robust MEMS gyroscope

Optoelectronic study and annealing stability of room temperature pulsed laser ablated ZnSe polycrystalline thin films

This paper presents a multi-axis low-cost soft magnetic tactile sensor with a high force range for force feedback in robotic surgical systems. The proposed sensor is designed to fully decouple the output response for normal, shear and angular forces. The proposed sensor is fabricated using rapid prototyping techniques and utilizes Neodymium magnets embedded in an elastomer over Hall sensors such that their displacement produces a voltage change that can be used to calculate the applied force. The initial spacing between the magnets and the Hall sensors is optimized to achieve a large displacement range using finite element method (FEM) simulations. The experimental characterization of the proposed sensor is performed for applied force in normal, shear and 45° angular direction. The force sensitivity of the proposed sensor in normal, shear and angular directions is 16 mV/N, 30 mV/N and 81 mV/N, respectively, with minimum mechanical crosstalk. The force range for the normal, shear and angular direction is obtained as 0–20 N, 0–3.5 N and 0–1.5 N, respectively. The proposed sensor shows a perfectly linear behavior and a low hysteresis error of 8.3%, making it suitable for tactile sensing and biomedical applications. The effect of the material properties of the elastomer on force ranges and sensitivity values of the proposed sensor is also discussed.

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Rana I. Shakoor

Papers

Design, simulation and testing of electrostatic SOI MUMPs based microgripper integrated with capacitive contact sensor

Optoelectronic properties and temperature dependent mechanisms of composite-hydroxide-mediated approach for the synthesis of CdO nanomaterials

Design, damping estimation and experimental characterization of decoupled 3-DoF robust MEMS gyroscope

Optoelectronic study and annealing stability of room temperature pulsed laser ablated ZnSe polycrystalline thin films

A Soft Multi-Axis High Force Range Magnetic Tactile Sensor for Force Feedback in Robotic Surgical Systems