System integration of MEMS devices on flexible substrate for fully implantable cochlear implant applications

Download
2019
Soydan, Alper Kaan
This master thesis is a result of multidisciplinary research bringing together concepts in electronics engineering, implant technologies, materials science, microfabrication, and device physics. Advancements in healthcare technology and in-vivo implants, electronic devices implemented on flexible substrates are highly demanded in the near future. In order to create a physically flexible device which consists of rigid sub-systems serving distinct purposes and made up of varying types of materials, we need reliable and durable integration methods for each sub-system. Moreover, the connection of these subsystems on a flexible substrate is a new subject that requires development. Furthermore, developed system has to be implantable and biocompatible. Under these concerns, the aim of this master thesis is to develop physically flexible, implantable and biocompatible system by the application of new methods to integrate rigid components to flexible substrate. Rigid components can be micro electromechanical system (MEMS) based sensors chips and CMOS electronics. Since advancement in semiconductor technology requires multichip integration and trending 3D integration techniques, through silicon via technology is utilized in this thesis to solve multichip MEMS integration challenges. Flexible substrate which houses the overall system is a polymeric and biocompatible material for this study. The thesis starts by introducing the subject by giving the motivation of the study and the literature review of the field. Next, the methods and the applications of the study will be given in two main fabrication chapters. Development of a wafer level, void free TSV fabrication process flow was developed. TSV structures with 100 µm diameter and 350 µm depth were copper filled with via sealing and bottom-up electroplating process which is a two-step technique. Fabrication of parylene flexible substrate specifically designed to designate MEMS piezoelectric cantilever chips was presented. Four-point Kelvin measurement tests explained that yields 0.8 mΩ average TSV resistance on fabricated TSVs and feasibility study of TSV integration to MEMS piezoelectric resonator devices has been presented in the results and discussion chapter. Then, Finally, the conclusions and the future work are explained.

Suggestions

Design, fabrication, and characterization of micro thermal actuators
Gülcüler, Buğrahan; Azgın, Kıvanç; Department of Mechanical Engineering (2020-11)
This thesis presents the design, fabrication, and characterization of V-Type thermal actuators, which will be used in an actuator system that is planned to be a tensile and compressive test setup to characterize the expandible cells by the help of double- ended tuning fork resonators as a force sensing mechanism. Actuators are serially packed to increase the generated force by them while maintaining the same deflection values. They have been connected to the overall system by springs to create a force on te...
Fabrication and Feasibility of Through Silicon Via for 3D MEMS Resonator Integration
Soydan, Alper Kaan; Yüksel, Mehmet Berat; Işık Akçakaya, Dilek; Külah, Haluk (2019-10-30)
In this study, development of a wafer level, void free TSV fabrication process flow and feasibility study of TSV integration to MEMS piezoelectric resonator devices have been presented. TSV structures with 100 mu m diameter and 350 mu m depth were copper filled with via sealing and bottom-up electroplating process which is a two-step technique. Four-point Kelvin measurements showed 0.8 m Omega TSV resistance on fabricated TSVs. Furthermore, TSV frames were epoxy bonded to MEMS acoustic transducers, which sh...
Thin Film PZT Acoustic Sensor for Fully Implantable Cochlear Implants
İlik, Bedirhan; Koyuncuoğlu, Aziz; Uluşan, Hasan; Chamanıan, Salar; Işık Akçakaya, Dilek; Şardan Sukas, Özlem; Külah, Haluk (2017-09-06)
This paper presents design and fabrication of a MEMS-based thin film piezoelectric transducer to be placed on an eardrum for fully-implantable cochlear implant (FICI) applications. Resonating at a specific frequency within the hearing band, the transducer senses eardrum vibration and generates the required voltage output for the stimulating circuitry. Moreover, high sensitivity of the sensor, 391.9 mV/Pa @900 Hz, decreases the required power for neural stimulation. The transducer provides highest voltage ou...
High performance CMOS capacitive interface circuits for MEMS gyroscopes
Silay, Kanber Mithat; Akar, Tayfun; Department of Electrical and Electronics Engineering (2006)
This thesis reports the development and analysis of high performance CMOS readout electronics for increasing the performance of MEMS gyroscopes developed at Middle East Technical University (METU). These readout electronics are based on unity gain buffers implemented with source followers. High impedance node biasing problem present in capacitive interfaces is solved with the implementation of a transistor operating in the subthreshold region. A generalized fully differential gyroscope model with force feed...
Engineering advanced polymeric surfaces for smart systems in biomedicine, biology, material science and nanotecnology: A cross-disciplinary approach of Biology, Chemistry and Physics (BIOPOLYSURF)
Hasırcı, Vasıf Nejat(2008-9-30)
The enormous potential of Biology in combination with Chemistry and Physics will lead to break-through advances in material science and to an abundant wealth of exploitable developments, Chemistry and Physics offer advanced tools for synthesis, characterization, theoretical understanding and manufacture of materials and devices, while Biology offer a window into the most sophisticated collection of functional nanostructures that exist. The inspiration searched in Nature will expand not only lo the use of th...
Citation Formats
A. K. Soydan, “System integration of MEMS devices on flexible substrate for fully implantable cochlear implant applications,” Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Micro and Nanotechnology., Middle East Technical University, 2019.