Performance analysis of zinc oxide piezoelectric MEMS energy harvester

This paper presents the design and analysis of MEMS piezoelectric energy harvester. Zinc oxide (ZnO) MEMS piezoelectric energy harvester has been utilized as piezoelectrically active cantilever for mechanical to electrical transduction. A COMSOL Multiphysics model was used which provide accurate information on the frequency, stress and voltage output of a ZnO piezoelectric energy harvester. Few design parameters have been studied which are rectangular cantilever, triangular cantilever, rectangular cantilever with proof mass and using different types of piezoelectric materials. The effects of varying geometrical dimensions of the device were also investigated. From simulation results, it was found out that ZnO piezoelectric energy harvester with the length of 150 μm, width 50 μm and thickness of 4 μm generates 9.9184 V electric potential under the resonance frequency of 0.71 MHz and 1 μN/m2 mechanical force applied

Design and Simulation of MEMS Hemholtz Resonator for Acoustic Energy Harvester

An acoustic energy harvester using Helmholtz resonator with piezoelectric circular diaphragm has been studied using COMSOL Multiphysics 5.1. In this paper, multiple designs considerations for MEMS Helmholtz resonator and piezoelectric circular diaphragm including the length and radius of the tube, the radius of the cavity and the thickness of the circular piezoelectric cantilever have been studied and investigated by varying it’s size with 5 different values for each parts in order to find the best size for optimum output voltage. The input pressure have been set to 1Pa as default. The simulation results demonstrated that under the same condition, a higher output pressure can be formed by having smaller tube radius and bigger cavity radius of the Helmholtz resonator. On the other hand, the interaction between air pressure’s vibration and piezoelectric diaphragm plays an important role in determining the amount of harvested acoustic power and the position of piezoelectric circular diaphragm in the Helmholtz resonator is at the optimum when it is placed at the end of the resonator compared to at the beginning of the resonator’s tube

Flexible PVDF thin film as piezoelectric energy harvester

This aim of this paper is to study the potential of Polyvinylidene Fluoride (PVDF) polymeric piezoelectric film as an energy harvester for daily application use. PVDF offers several advantages over other piezoelectric materials such as high chemical strength and stability, high piezoelectric properties and biocompatible. Several investigations were carried out in this project which comprises of simulation, functionality test and application test. For functionality test, the highest voltage produced for a single film PVDF is 0.368 V which charges up a capacitor to 0.219 V in one minute. The highest voltage produced by multiple PVDF films is 1.238 V by stacking 10 films of PVDF in parallel which charges up to 0.688 V in one minute. For application test, 5 pieces of PVDF films were attached to a glove to generate some voltage during fingers bending activity. The highest output voltage recorded is 0.184 V which stores 0.101 V in a capacitor after 200 times of hand bending and releasing. As a conclusion, PVDF has a good potential as an alternative energy for daily application use. Combination of PVDF energy harvester system with proper power optimization circuit will open up rooms of research opportunities in energy harvester system with promising prospect in self-powered wireless electronics devices for Internet of Things application

Queue backlog as a node metric for RPL protocol

The current de-facto routing protocol over WSN developed by IETF Working Group (6LOWPAN) named as Routing Protocol for Low Power and Lossy networks (RPL) [1], to enable IPv6 packets carrying over IEEE 802.4 and to empower the usage of IoT over WSN. Because of the potential large networks, number of nodes and the fact that multiple coexisting applications will be running in the same physical layer, RPL in the network layer faces throughput challenges. For the purpose of overcoming these problems many researchers focused on multipath solutions including a Back-Pressure routing protocol for data collection called BackIP [2], however it shows a superior throughput performance, BackIP have shortcomings of higher delay and limited applicability. In this paper, we introduce a node metric based on nodes Queue Backlogs for RPL protocol, which leads to better throughput performance while maintaining the delay and the ability to use with the different network applications. This metric depends on the Packet Queue length of the nodes with the consideration of other link and node metrics, like ETX or Energy usage, leading to better load balancing in the network. Moreover we discuss the needed design changes to enable our metric to perform in an efficient way. Keywords-IOT, RPL, WSN, Back Pressure, Queue Backlog, Objective Functio

Silicon carbide schottky diodes forward and reverse current properties upon fast electron radiation

This paper investigates on the reaction of 10 and 15MGy, 3MeV electron irradiation upon off-the-shelves (commercial) Silicon Carbide Schottky diodes from Infineon Technologies (model: IDH08SG60C) and STMicroelectronics (model: STPSC806). Such irradiation reduces the forward-bias current. The reduction is mainly due to the significant increase of the series resistance (i.e. Infineon: 1.45Ω at before irradiation → 121×103 Ω at 15MGy); STMicroelectronics: 1.44Ω at before irradiation → 2.1×109 Ω at 15MGy). This increase in series resistance gives 4.6 and 8.2 orders of magnitude reduction for the forward-bias current density of Infineon and STMicroelectronics respectively. It is also observed that the ideality factor and the saturation current of the diodes increases with increasing dose (i.e. ideality factor- Infineon: 1.01 at before irradiation → 1.05 at 15MGy; STMicroelectronics: 1.02 at before irradiation → 1.3 at 15MGy | saturation current- Infineon: 1.6×10-17A at before irradiation → 2.5×10-17A at 15MGy; STMicroelectronics: 2.4×10-15A at before irradiation → 8×10-15A at 15MGy). Reverse-bias leakage current density in model by Infineon increases by one order of magnitude after 15MGy irradiation, however, in model by STMicroelectronics decreases by one order of magnitude. Overall, for these particular samples studied, Infineon devices have shown to be better in quality and more radiation resistance toward electron irradiation in forward-bias operation while STMicroelectronics exhibit better characteristics in reverse-bias operation

Human gait recognition: viewing angle effect on normal walking pattern

Gait recognition has recently gained interest of researchers as it performs identification of subjects at a distance from the camera. However, due to the changes in the viewing angles, it gets cumbersome for a system to perform recognition based on the walking pattern of an individual. In this work, the aim is to propose a simple baseline method for the purpose of human recognition based on the shape of its body and walking pattern when the subject is observed from different viewing angles. The recognition is also tested on the subjects in a scenario where the individual subjects are registered while walking in normal walking pattern followed by the testing in normal walking mode, apart from being observed at different viewing angles. Gait periodicity is estimated after extracting the silhouettes of an individual, followed by obtaining the total silhouette representation of an individual using Matlab. The total silhouette representations obtained from the probe gait data are compared to the gallery gait data representations for the purpose of similarity computation by calculating the RMS value between the said representations. Higher the value, lesser is the similarity & vice versa

RECENT TRENDS IN DENGUE DETECTION METHODS USING BIOSENSORS

ABSTRACT: Dengue illness is an infectious tropical disease, transmitted by Aedes mosquitos, that poses a serious health threat to the tropical world. This disease causes widespread infection worldwide, with about 50 million cases of dengue occurring per annum out of which 500,000 recorded cases of dengue hemorrhagic fever and 22,000 deaths.  Currently, there are no effective vaccines available to prevent the spread of the infection. Accurate and rapid laboratory diagnostic tests are required for early detection to reduce patient mortality rate. In this paper,  common laboratory diagnosis methods for detecting dengue virus infection are discussed. Currently, virus isolation, RT-PCR and serology methods provide the most direct and accurate response for detection of dengue. However, these methods require tedious steps, expensive requirements and expert staffs. Recent research have proposed the usage of biosensors as an alternative new technology for detection of dengue. In this work, various types of biosensors such as electrochemical, piezoelectric, and optical biosensor have been described and compared to evaluate their effectiveness in dengue detection.  It is observed that the optical biosensor offers the best detection due to its high sensitivity as compared to others, although it is popularly known as an expensive method. Alternatively, the use of electrochemical and piezoelectric biosensors (QCM) is highly recommended for detection of dengue due to their ease-of-use, low cost, low reagent consumption, disposability, and minimal sample preparation. These approaches have the potential to improve the rate of survival, particularly in resource-limited countries. ABSTRAK: Virus denggi adalah penyakit berjangkit tropika bawaan nyamuk Aedes yang menimbulkan ancaman serius kepada kesihatan global. Penyakit ini menyebabkan jangkitan yang meluas di seluruh dunia, dengan kira-kira 50 juta kes denggi yang berlaku setiap tahun di mana 500,000 kes demam denggi berdarah dan 22,000 kematian direkodkan. Buat masa ini, tiada vaksin yang berkesan untuk mencegah penyebaran jangkitan ini. Ujian diagnostik makmal yang cepat dan tepat diperlukan untuk pengesanan denggi awal untuk mengurangkan kadar kematian pesakit. Dalam artikel ini, kaedah diagnosis makmal yang biasa dilakukan untuk mengesahkan jangkitan virus denggi akan dibincangkan. Pada masa kini, kaedah pengasingan virus, RT-PCR dan serologi adalah tindak balas yang paling cepat dan tepat untuk mengesan denggi. Walau bagaimanapun, kaedah-kaedah ini memerlukan langkah-langkah yang melecehkan, kos penyelenggaraan yang tinggi dan kakitangan  yang terlatih.  Penyelidikan terkini telah mencadangkan penggunaan biosensor sebagai teknologi baru alternatif untuk mengesan denggi.  Dalam artikel  ini juga pelbagai jenis biosensor seperti biosensor elektrokimia, piezoelektrik, dan biosensor optik telah dijelaskan dan dibandingkan untuk menilai keberkesanannya dalam pengesanan denggi. Difahamkan bahawa biosensor optik menawarkan pengesanan terbaik kerana kepekaannya yang tinggi berbanding dengan yang lain, walaupun ia dikenali sebagai kaedah berkos tinggi. Sebaliknya, biosensor elektrokimia dan piezoelektrik (QCM) sangat disyorkan untuk mengesan denggi kerana ia mudah digunakan, berkos rendah, penggunaan bahan uji yang terhad, boleh dipakai buang, dan mempunyai penyediaan sampel yang minima. Pendekatan-pendekatan ini berpotensi untuk meningkatkan kadar kemandirian di kawasan-kawasan sumber terhad

Reliability study of silicon carbide Schottky Diode with fast electron irradiation

The impact of fast electron exposure upon the performance of commercial silicon carbide Schottky diodes has been studied. Under 3 MeV electrons, absorbed dose of 10 and 15 MGy at room temperature, the forward current density-voltage characteristic of INFINEON and STMICROELECTRONICS devices have been decreased by 4.6 and 8.2 orders of magnitude respectively. The reduction is associated with the significant rise in the series resistance (INFINEON: 1.45 Ω to 121×103 Ω; STMICROELECTRONICS: 1.44 Ω to 2.1 × 109 Ω) due to the irradiation-induced defects. Besides that, the reverse leakage current density in INFINEON increased by one order of magnitude while reverse leakage current density in STMICROELECTRONICS decreased by about one order of magnitude. We have also observed an increase in ideality factor (INFINEON: 1.01 to 1.05; STMICROELECTRONICS: 1.02 to 1.3) and saturation current (INFINEON: 1.6×10-17 A to 2.5×10-17 A; STMICROELECTRONICS: 2.4×10-15 A to 8 × 10-15 A) as a result of electron irradiation. Overall, for particular devices studied, INFINEON have better quality devices and more radiation resistance compared to STMICROELECTRONICS

Rheological behaviour and thermal conductivity of polyvinyl ether lubricant modified with sio2-tio2 nanoparticles for refrigeration system

Before any nanolubricant is being applied in a refrigeration system, its thermo-physical properties shall be investigated. In this paper, hybrid nanolubricant is prepared by dispersing SiO2-TiO2 nanoparticles at 50:50 composition ratio into the polyvinyl ether (PVE) compressor lubricant using a two-step method. The investi�gation was done for volume concentrations from 0.01 to 0.10% under temperature range of 303 to 353 K. The Newtonian behaviour of the nanolubricant was obtained, and relative thermo-physical enhancement was determined by comparing its performance to the pure lubricant. It was observed that the maximum increment viscosity does not exceed 3% from the base fluid, while thermal conductivity for 0.1% concentration increases up to 1.6%. Overall observation also reveals that both rheological and thermal properties increase by increasing concentrations, but the same properties decrease with temperature. An interesting finding is the nanolubricant had viscosity decrement than the pure lubricant specifically at 303 K. New regression models were suggested for thermo-physical properties with high accuracy R-squared values of 0.9989 and 0.9920 for viscosity and thermal conductivity, respectively. As a conclusion, SiO2-TiO2/PVE nanolubricant is recommended in refrigeration sys�tems with a volume concentration of less than 0.10%