Design and optimization of a novel tri-axial miniature ear-plug piezoresistive accelerometer with nanoscale piezoresistors ab 49.99 € als Taschenbuch: Dissertationsschrift. Aus dem Bereich: Bücher, Kunst & Musik,
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Design and optimization of a novel tri-axial miniature ear-plug piezoresistive accelerometer with nanoscale piezoresistors ab 49.99 EURO Dissertationsschrift
Design and optimization of a novel tri-axial miniature ear-plug piezoresistive accelerometer with nanoscale piezoresistors ab 39.99 EURO
An automobile exhaust system has several functions. Originally, it was used for silencing the noise caused by high pressure exhaust gases leaving the engine and for transporting these hot and toxic gases away from the driver's compartment. The automotive muffler has to be able to allow the passage of exhaust gases whilst restricting the transmission of sound. The durability of that part of the exhaust muffler is therefore crucial. Hence one of important factor for durability is its resonance and corresponding mode shapes. The numerical method involves exhaust muffler design by modeling tool CATIA and meshing of the model is done by using Altair's pre-processing tool HyperMesh. Normal modal analysis is performed by using Msc Nastran.. The results are viewed through Altair's post-processing tool HyperView. The experimental method involves experiment is to conduct an test on a muffler system. For this impact test, an impact hammer was used to provide the input force and an tri-axial accelerometer was used to measure the output response. FFT analyser is used to remove the unwanted signals and it transfers the signals to the software. In order to determine the resonance frequencies
Health and physical activity are intimately connected and the concern for health keeps on increasing. These make the measurement of physical activity an important issue. The purpose of this project was to develop a prototype of a physical activity monitor. The device can transmit the acquired data making a detailed study possible. The prototype based on a tri-axial accelerometer was successfully produced. It can be personalized by setting up the time and the recommended daily activity. The registered data can be uploaded via Bluetooth to mobile phones. The memory can store more than 18 hours with a sample rate of 1 Hz.
This work focuses on the design improvement of a tri-axial piezoresistive accelerometer specifically designed for head injuries monitoring where medium-G impacts are common, for example in sports such as motorsport and American football. Given the particular biomedical and biomechanical application the device requires the highest sensitivity achievable with a single proof mass approach, where basically all three axes of measurements are detected with a single mass suspended by surrounding beams. Moreover, a very low error, below 1%, is expected for these type of applications where accuracy is paramount. The optimization method used is based on the progressive increment of the sensor mass moment of inertia (MMI) in all axes. The theoretical hypothesis to confirm is that an increment of MMI of the device proof mass would determine an increment of device sensitivity with a simultaneous reduction of cross-talk in the particular axis under study. The work numerically demonstrates the hypothesis validity by simulating the optimized device mechanical structures with Finite Element Method. A final optimal shape is selected as the best possible output of the optimization process.
Doctoral Thesis / Dissertation from the year 2013 in the subject Design (Industry, Graphics, Fashion), grade: N/A, Cranfield University, language: English, abstract: This work aims at the advancement of state-of-art accelerometer design and optimization methodology by developing an ear-plug accelerometer for race car drivers based on a novel mechanical principle. The accelerometer is used for the measurements of head acceleration when an injurious event occurs. Main requirements for such sensor are miniaturization (2×2 mm), because the device must be placed into the driver earpiece, and its measurement accuracy (i.e. high sensitivity, low crosstalk and low nonlinearity) since the device is used for safety monitoring purpose. A micro-electro-mechanical system (MEMS)-based (bulk micromachined) piezoresistive accelerometer was selected as enabling technology for the development of the sensor. The primary accelerometer elements that can be manipulated during the design stage are: the sensing element (piezoresistors), the micromechanical structure and the measurements circuit. Each of these elements has been specifically designed in order to maximize the sensor performance and to achieve the miniaturization required for the studied application. To achieve accelerometer high sensitivity and miniaturization silicon nanowires (SiNWs) as nanometer scale piezoresistors are adopted as sensing elements. Currently this technology is at an infancy stage, but very promising through the exploitation of the "Giant piezoresistance effect" of SiNWs. This work then measures the potential of the SiNWs as nanoscale piezoresistors by calculating the major performance indexes, both electrical and mechanical, of the novel accelerometer. The results clearly demonstrate that the use of nanoscale piezoresistors boosts the sensitivity by 30 times in comparison to conventional microscale piezoresistors. A feasibility study on nanowires fabrication by both top-down and bottom-up approaches is also carried out.The micromechanical structure used for the design of the accelerometer is an optimized highly symmetric geometry chosen for its self-cancelling property. This work, for the first time, presents an optimization process of the accelerometer micromechanical structure based on a novel mechanical principle, which simultaneously increases the sensitivity and reduces the cross-sensitivity progressively. In the open literature among highly symmetric geometries no other study has to date reported enhancement of the electrical sensitivity and reduction of the cross-talk at the same time.
The sign language is an important method of communication for deaf and dumb people. As sign language is a well-structured paradigm, each gesture has a meaning assigned to it. Gestures or the Sign language is the combination of orientations, movement of the hands, arms or body and facial expressions. The communication of deaf and dumb people is not easily predicted by the common people. In order to overcome the barrier in communication an advanced system is required. A Security assistive system is proposed, comprising of a Tri-axial accelerometer sensor through which the gestures are recognized and correspondingly for each gesture the threshold value and particular voice output is obtained. Vibration sensor continuously senses the state of a person and it sends the message to the end user when it is vibrated.The developed system aids the deaf and dumb people to communicate with the normal people without the requirement of an interpreter. It helps the deaf and dumb people to act independently at the emergency conditions and also lowers the communication barrier.