Novel wireless RF-bioMEMS implant sensors of metamaterials

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buir.advisorDemir, Hilmi Volkan
dc.contributor.authorMelik, Rohat
dc.date.accessioned2016-01-08T18:17:10Z
dc.date.available2016-01-08T18:17:10Z
dc.date.issued2010
dc.departmentDepartment of Electrical and Electronics Engineeringen_US
dc.descriptionAnkara : The Department of Electrical and Electronics Engineering and the Institute of Engineering and Sciences of Bilkent University, 2010.en_US
dc.descriptionThesis (Ph. D.) -- Bilkent University, 2010.en_US
dc.descriptionIncludes bibliographical references leaves 301-308.en_US
dc.description.abstractToday approximately one out of ten patients with a major bone fracture does not heal properly because of the inability to monitor fracture healing. Standard radiography is not capable of discriminating whether bone healing is occurring normally or aberrantly. To solve this problem, we proposed and developed a new enabling technology of implantable wireless sensors that monitor mechanical strain on implanted hardware telemetrically in real time outside the body. This is intended to provide clinicians with a powerful capability to asses fracture healing following the surgical treatment. Here we present the proof-of-concept in vitro and ex vivo demonstrations of bio-compatible radio-frequency (RF) micro-electro-mechanical system (MEMS) strain sensors for wireless strain sensing to monitor healing process. The operating frequency of these sensors shifts under mechanical loading; this shift is related to the surface strain of the implantable test material. In this thesis, for the first time, we developed and demonstrated a new class of bio-implant metamaterial-based wireless strain sensors that make use of their unique structural advantages in sensing, opening up important directions for the applications of metamaterials. These custom-design metamaterials exhibit better performance in remote sensing than traditional RF structures (e.g., spiral coils). Despite their small size, these meta-sensors feature a low enough operating frequency to avoid otherwise strong background absorption of soft tissue and yet yield higher Q-factors (because of their splits with high electric field density) compared to the spiral structures. We also designed and fabricated flexible metamaterial sensors to exhibit a high level of linearity, which can also conveniently be used on non-flat surfaces. Innovating on the idea of integrating metamaterials, we proposed and implemented a novel architecture of ‘nested metamaterials’ that incorporate multiple split ring resonators integrated into a compact nested structure to measure strain telemetrically over a thick body of soft tissue. We experimentally verified that this nested metamaterial architecture outperforms classical metamaterial structures in telemetric strain sensing. As a scientific breakthrough, by employing our nested metamaterial design, we succeeded in reducing the electrical length of the sensor chip down to λo/400 and achieved telemetric operation across thick soft tissue with a tissue thickness up to 20 cm, while using only sub-cm implantable chip size (compatible with typical orthopaedic trauma implants and instruments). As a result, with nested metamaterials, we successfully demonstrated wireless strain sensing on sheep’s fractured metatarsal and femur using our sensors integrated on stainless steel fixation plates and on sheep’s spine using directly attached sensors in animal models. This depth of wireless sensing has proved to suffice for a vast portfolio of bone fracture (including spine) and trauma care applications in body, as also supported by ongoing in vivo experiments in live animal models in collaboration with biomechanical and medical doctors. Herein, for all generations of our RF-bioMEMS implant sensors, this dissertation presents a thorough documentation of the device conception, design, modeling, fabrication, device characterization, and system testing and analyses. This thesis work paves the way for “smart” orthopaedic trauma implants, and enables further possible innovations for future healthcare.en_US
dc.description.degreePh.D.en_US
dc.description.statementofresponsibilityMelik, Rohaten_US
dc.format.extentxxviii, 308 leaves, illustrationsen_US
dc.identifier.urihttp://hdl.handle.net/11693/15348
dc.language.isoEnglishen_US
dc.publisherBilkent Universityen_US
dc.rightsinfo:eu-repo/semantics/openAccessen_US
dc.subjectmetamaterialsen_US
dc.subjectnested metamaterialen_US
dc.subjectsplit ring resonatorsen_US
dc.subjectmicrowave resonatorsen_US
dc.subjectbioMEMS sensorsen_US
dc.subjectRF-MEMSen_US
dc.subjecttelemetryen_US
dc.subjectremote sensingen_US
dc.subjectmechanical loadingen_US
dc.subjectstrainen_US
dc.subjectsensitivityen_US
dc.subjectlinearityen_US
dc.subjectresonance frequencyen_US
dc.subjectquality factor (Q-factor)en_US
dc.subjectfrequency shiften_US
dc.subjectbio-implanten_US
dc.subjectbiocompatibilityen_US
dc.subject.lccTK454.4.M3 M44 2010en_US
dc.subject.lcshMetamaterials.en_US
dc.subject.lcshResonators.en_US
dc.subject.lcshRadio frequency microelectromechanical systems.en_US
dc.subject.lcshMicrowave circuits.en_US
dc.subject.lcshBioMEMS.en_US
dc.subject.lcshBiosensors.en_US
dc.subject.lcshNanostructures.en_US
dc.titleNovel wireless RF-bioMEMS implant sensors of metamaterialsen_US
dc.typeThesisen_US

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