Bio-implantable passive on-chip RF-MEMS strain sensing resonators for orthopaedic applications

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buir.contributor.authorDemir, Hilmi Volkan
buir.contributor.orcidDemir, Hilmi Volkan|0000-0003-1793-112X
dc.citation.issueNumber11en_US
dc.citation.volumeNumber18en_US
dc.contributor.authorMelik, R.en_US
dc.contributor.authorPerkgoz, N. K.en_US
dc.contributor.authorUnal, E.en_US
dc.contributor.authorPuttlitz, C.en_US
dc.contributor.authorDemir, Hilmi Volkanen_US
dc.date.accessioned2016-02-08T10:07:19Z
dc.date.available2016-02-08T10:07:19Z
dc.date.issued2008en_US
dc.departmentDepartment of Electrical and Electronics Engineeringen_US
dc.departmentDepartment of Physicsen_US
dc.description.abstractOne out of ten bone fractures does not heal properly due to improper load distribution and strain profiles during the healing process. To provide implantable tools for the assessment of bone fractures, we have designed novel, bio-implantable, passive, on-chip, RF-MEMS strain sensors that rely on the resonance frequency shift with mechanical deformation. For this purpose, we modeled, fabricated and experimentally characterized two on-chip sensors with high quality factors for in vivo implantation. One of the sensors has an area of ∼0.12 mm2 with a quality factor of ∼60 and the other has an area of ∼0.07 mm2 with a quality factor of ∼70. To monitor the mechanical deformation by measuring the change in the resonance frequencies with the applied load, we employed a controllable, point load applying experimental setup designed and constructed for in vitro characterization. In the case of the sensor with the larger area, when we apply a load of 3920 N, we obtain a frequency shift of ∼330 MHz and a quality factor of ∼76. For the smaller sensor, the frequency shift and the quality factor are increased to 360 MHz and 95, respectively. These data demonstrate that our sensor chips have the capacity to withstand relatively high physiologic loads, and that the concomitant and very large resonant frequency shift with the applied load is achieved while maintaining a high signal quality factor. These experiments demonstrate that these novel sensors have the capacity for producing high sensitivity strain readout, even when the total device area is considerably small. Also, we have demonstrated that our bio-implantable, passive sensors deliver a telemetric, real-time readout of the strain on a chip. Placing two more resonators on the sides of the sensor to serve as transmitter and receiver antennas, we achieved to transfer contactless power and read out loads in the absence of direct wiring to the sensor. With this model, where telemetric measurements become simpler due to the fact that all sensor system is built on the same chip, we obtain a frequency shift of ∼190 MHz with an increase in the quality factor from ∼38 to ∼46 when a load of 3920 N is applied. Therefore, as a first proof of concept, we have demonstrated the feasibility of our on-chip strain sensors for monitoring the mechanical deformation using telemetry-based systems.en_US
dc.identifier.doi10.1088/0960-1317/18/11/115017en_US
dc.identifier.eissn1361-6439
dc.identifier.issn0960-1317
dc.identifier.urihttp://hdl.handle.net/11693/22979
dc.language.isoEnglishen_US
dc.publisherInstitute of Physics Publishing Ltd.en_US
dc.relation.isversionofhttp://doi.org/10.1088/0960-1317/18/11/115017en_US
dc.source.titleJournal of Micromechanics and Microengineeringen_US
dc.titleBio-implantable passive on-chip RF-MEMS strain sensing resonators for orthopaedic applicationsen_US
dc.typeArticleen_US
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Department of Electrical and Electronics Engineering
Department of Physics
Institute of Materials Science and Nanotechnology (UNAM)