Koklear implant uygulamaları için mems piezoelektrik enerji üreteci.

This thesis proposes a novel method for eliminating the battery dependency of cochlear implant users. The proposed method utilizes a MEMS harvester mounted onto the eardrum. The harvester converts the vibrations of the eardrum to electricity and supplies the generated electricity to the cochlear implant; thus, reducing the battery replacement/recharge problems. As an extension of the proposed method, by utilizing a multi-frequency harvester, electricity can be generated while sensing the frequency of the vibration. By transferring the generated electrical signals to corresponding regions inside the cochlea, au ditory nerve can be stimulated. Thus, a fully implantable and self-powered cochlear implant can be realized with the harvester, which electromechanically mimics the operation of cochlea. Modeling, design, and optimization studies are conducted by considering operational conditions. Due to comparable mass and stiffness parameters of the eardrum and the harvester, structures are coupled using finite element method (FEM). Initially, the harvester is modeled, and a macro-scale prototype is fabricated for verification. Then, a membrane model is developed utilizing FEM. Eventually, these structures are coupled and optimized. Among possible methods for fabrication of piezoelectric energy harvester, bulk piezoceramics is preferred due to its high strain coefficients and high output power potential. A fabrication method is implemented to integrate piezoceramics into MEMS. The fabrication process involves low-temperature bonding and thinning processes. Finally, the fabricated devices are tested, and it is shown that the harvester is capable of supplying electrical power of 1.33 μW at 0.1g while resonating at its resonance frequency of 474 Hz.M.S. - Master of Scienc

Sensing and Harvesting Pressure Fluctuations in Harsh Environments

Pressure is one of the most frequent and important parameters utilized in many applications to provide critical information about the operation of a system as well as a potential mechanical energy source. Among various pressure-related devices, very few function in harsh environment which includes high temperature, high pressure, highly corrosive, or biofouling conditions. In the first part of this dissertation, a high temperature pressure sensor with a novel concentric ring-circle-shape design is proposed specifically for the geothermal applications with detailed modeling, fabrication, and characterization results. A concentrically matched ring-circular capacitance pressure sensor design is proposed to tackle the common mode noise problem of km-long cables in geothermal wells. Furthermore, to provide a high temperature and corrosive environment survivability, silicon carbide is utilized as it has superior material properties as compared to silicon in harsh environments. Experimentally, it was shown that the novel design can provide differential capacitance output at temperatures of 180℃ and capacitances ranging between 0.14 pF to 1.45 pF were observed from a sensor designed to operate under 1 MPa. In the second part of this dissertation, an energy harvester application is proposed to make the use of pressure fluctuations within the lateral ventricles of the brain which is a biofouling environment. This time, a concentric ring-circular design is utilized to convert the mechanical pressure fluctuations to electrical energy efficiently. The harvesters were fabricated using aluminum nitride as the piezoelectric material and the increase in efficiency of the proposed design was shown as characterized by both in-air and underwater tests. A 3D-printed lateral ventricle mockup setup was used to mimic the operation of the harvester in lateral ventricles and the harvester with a diameter of 2.5 mm generated a power of 0.62 nW. Moreover, considering the potential issues in deployment and mounting, a flexible harvester was developed using PVDF and PET materials and under water characterization the harvester with 3 mm diameter resulted in power of 1.75 nW

Sensing and Harvesting Pressure Fluctuations in Harsh Environments

Pressure is one of the most frequent and important parameters utilized in many applications to provide critical information about the operation of a system as well as a potential mechanical energy source. Among various pressure-related devices, very few function in harsh environment which includes high temperature, high pressure, highly corrosive, or biofouling conditions. In the first part of this dissertation, a high temperature pressure sensor with a novel concentric ring-circle-shape design is proposed specifically for the geothermal applications with detailed modeling, fabrication, and characterization results. A concentrically matched ring-circular capacitance pressure sensor design is proposed to tackle the common mode noise problem of km-long cables in geothermal wells. Furthermore, to provide a high temperature and corrosive environment survivability, silicon carbide is utilized as it has superior material properties as compared to silicon in harsh environments. Experimentally, it was shown that the novel design can provide differential capacitance output at temperatures of 180℃ and capacitances ranging between 0.14 pF to 1.45 pF were observed from a sensor designed to operate under 1 MPa. In the second part of this dissertation, an energy harvester application is proposed to make the use of pressure fluctuations within the lateral ventricles of the brain which is a biofouling environment. This time, a concentric ring-circular design is utilized to convert the mechanical pressure fluctuations to electrical energy efficiently. The harvesters were fabricated using aluminum nitride as the piezoelectric material and the increase in efficiency of the proposed design was shown as characterized by both in-air and underwater tests. A 3D-printed lateral ventricle mockup setup was used to mimic the operation of the harvester in lateral ventricles and the harvester with a diameter of 2.5 mm generated a power of 0.62 nW. Moreover, considering the potential issues in deployment and mounting, a flexible harvester was developed using PVDF and PET materials and under water characterization the harvester with 3 mm diameter resulted in power of 1.75 nW

A novel method for piezoelectric energy harvesting from keyboard

This paper presents a novel method and apparatus for converting keystrokes to electrical energy using a resonant energy harvester, which can be coupled with keyboards. The state-of-the-art dome switch design is modified to excite the tip of the energy harvester beam. Piezoelectric transduction converts vibrations to electrical power. The energy harvester design is optimized to give highest voltage output under use conditions, and is fabricated. A close match is observed for the first natural frequency. When the piezoelectric energy harvester is excited at 7.62 Hz with tip excitation to emulate keyboard use, 16.95 mu W of power is generated

A parylene coating based room temperature wafer-level attachment method for MEMS integration with zero applied force

This paper reports a wafer-level attachment method using parylene as an interlayer material for integrating various shaped and fragile substrates into MEMS processes. In the proposed method, the substrates are placed on a handle wafer containing pillars and perforations, and coated with a standard parylene deposition process realized at room temperature, with no applied force. The substrate and the handle wafer are attached to each other via formation of a parylene interlayer. Only poor attachment is observed by utilizing a handle wafer containing pillars alone, as parylene cannot perfectly penetrate through the structures. The parylene penetration is significantly improved by introducing perforations to the handle wafer. It is experimentally shown that, with a perforated handle wafer containing pillar structures having 20 mu m height and 4.5 mm spacing, parylene completely fills the gap between the structures, and can successfully be used to attach substrates to each other. The shear strength between the attached substrates has been measured as 0.49 MPa, proving the feasibility of the method for integrating various materials into MEMS processes. As a demonstrator for the utilization of the attachment method in the microfabrication processes of sensors and actuators, a fragile 7 cm x 7 cm x 190 mu m PZT sheet has been attached to a handle wafer and processed successfully through a sample set of standard MEMS processes

A parylene coating based room temperature wafer-level attachment method for MEMS integration with zero applied force

This paper reports a wafer-level attachment method using parylene as an interlayer material for integrating various shaped and fragile substrates into MEMS processes. In the proposed method, the substrates are placed on a handle wafer containing pillars and perforations, and coated with a standard parylene deposition process realized at room temperature, with no applied force. The substrate and the handle wafer are attached to each other via formation of a parylene interlayer. Only poor attachment is observed by utilizing a handle wafer containing pillars alone, as parylene cannot perfectly penetrate through the structures. The parylene penetration is significantly improved by introducing perforations to the handle wafer. It is experimentally shown that, with a perforated handle wafer containing pillar structures having 20 mu m height and 4.5 mm spacing, parylene completely fills the gap between the structures, and can successfully be used to attach substrates to each other. The shear strength between the attached substrates has been measured as 0.49 MPa, proving the feasibility of the method for integrating various materials into MEMS processes. As a demonstrator for the utilization of the attachment method in the microfabrication processes of sensors and actuators, a fragile 7 cm x 7 cm x 190 mu m PZT sheet has been attached to a handle wafer and processed successfully through a sample set of standard MEMS processes

An energy harvesting cochlear implant

Bu buluş algılayıcı olarak kulak zan ya da orta kulak kemikçikleri üzerine yerleştirilen bir piezoelektrik titreşim enerjisi toplayıcı kullanan, bu sayede de gelen ses dalgalarının frekansını algılayıp aynı zamanda ılgılı duyu sinirlerini uyarabilecek elektriksel potansiyeli üretebilen bir total koklear implant hakkındadır Buluş standart koklear implant sistemlerinde kullanılan hana parçalan elimine ettiğinden hastaların aralıksız şekilde duyabilmesini sağlamaktadır Ayrıca sistem kendi enerjisini orta kulaktaki titreşimler vasıtası ile ürettiğinden, sürekli şan edilmesi gereken pil problemi de ortadan kalkmaktadır Buluşun algılayıcı kısmı mikro-elektro-mekanik sistemler (MEMS) üretim yöntemleri kullanılarak üretilmektedir Buluş iki ana parçadan oluşmaktadır, gelen sesin frekansını algılayan aynı zamanda da bu titreşimden enerji üreten algılayıcı, koklea içimdeki işitme sinirlerini uyaran elektrotlarThe invention is related to a totally implantable cochlear implant having a transducer which is a piezoelectric vibration energy harvester to be mounted on the ossicular chain or the tympanic membrane to detect the frequency of oscillations and generate the required voltage to stimulate the relevant auditory nerves. The invention enables patients' continuous access to sound, since it eliminates the outside components of conventional cochlear implants. The invention also eliminates the problem of battery need, since the transducer generates voltage required to stimulate auditory nerves from the vibrations of ossicular chain. The transducer is fabricated using Microelectromechanical Systems (MEMS) fabrication techniques. The invention incorporates of two main parts, a transducer acting both as a frequency detector and an energy harvester, and electrodes to stimulate the auditory nerve inside the cochle

A ROOM TEMPERATURE, ZERO FORCE, WAFER-LEVEL ATTACHMENT METHOD FOR MEMS INTEGRATION

This paper presents a wafer level attachment method for handling various shaped structures for MEMS processes, using parylene as an interlayer material. In this method, a handle wafer containing pillars and perforations is utilized, and structures are attached to the handle wafer through a parylene coating process realized at room temperature with no applied force. It is observed that pillars with 20 mu m height, 2.5 mm side length, and 4.5 mm spacing can successfully be used to attach two 4 '' substrates to each other. The shear strength between the attached substrates is measured as 0.49 MPa, proving the feasibility of the method for integrating various materials into MEMS processes

A novel method for piezoelectric energy harvesting from keyboard

This paper presents a novel method and apparatus for converting keystrokes to electrical energy using a resonant energy harvester, which can be coupled with keyboards. The state-of-the-art dome switch design is modified to excite the tip of the energy harvester beam. Piezoelectric transduction converts vibrations to electrical power. The energy harvester design is optimized to give highest voltage output under use conditions, and is fabricated. A close match is observed for the first natural frequency. When the piezoelectric energy harvester is excited at 7.62 Hz with tip excitation to emulate keyboard use, 16.95 mu W of power is generated

Piezoelectric cantilever prototype for energy harvesting in computing applications

This paper presents a piezoelectric energy harvester (PEH) to convert vibrations to electrical power. A unimorph cantilever beam is used to generate voltage on piezoelectric material bonded close to the anchor of the cantilever beam. A 4.85 x 1 x 0.04 cm structural layer with piezoelectric material yields peak-to-peak voltage of 64 V at the resonance frequency of the structure. The empirically confirmed maximum power output is close to 0.5 mW. The results from validation data on the observed structure has been correlated to the simulations in finite element method (FEM) program using piezoelectric analysis tools