title: Archimedean Spiral Pairs with no Electrical Connections as a Passive Wireless Implantable Sensor.
abstract: We have developed, modeled, fabricated, and tested a passive wireless sensor system that exhibits a linear frequency-displacement relationship. The displacement sensor is comprised of two anti-aligned Archimedean coils separated by an insulating dielectric layer. There are no electrical connections between the two coils and there are no onboard electronics. The two coils are inductively and capacitively coupled due to their close proximity. The sensor system is interrogated wirelessly by monitoring the return loss parameter from a vector network analyzer. The resonant frequency of the sensor is dependent on the displacement between the two coils. Due to changes in the inductive and capacitive coupling between the coils at different distances, the resonant frequency is modulated by coil separation. In a specified range, the frequency shift can be linearized with respect to coil separation. Batch fabrication techniques were used to fabricate copper coils for experimental testing with air as the dielectric. Through testing, we validated the performance of sensors as predicted within acceptable errors. Because of its simplicity, this displacement sensor has potential applications for in vivo sensing.
authors.affiliation: Rensselaer Polytechnic Institute, Troy, NY.
authors.forename: John F
authors.initials: JF
authors.lastname: Drazan
authors.affiliation: State University of New York College of Nanoscale Science and Engineering, Albany, NY.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Gunko
authors.affiliation: Rensselaer Polytechnic Institute, Troy, NY.
authors.forename: Matthew
authors.initials: M
authors.lastname: Dion
authors.affiliation: Rensselaer Polytechnic Institute, Troy, NY.
authors.forename: Omar
authors.initials: O
authors.lastname: Abdoun
authors.affiliation: State University of New York College of Nanoscale Science and Engineering, Albany, NY.
authors.forename: Nathaniel C
authors.initials: NC
authors.lastname: Cady
authors.affiliation: Rensselaer Polytechnic Institute, Troy, NY.
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Connor
authors.affiliation: Rensselaer Polytechnic Institute, Troy, NY.
authors.forename: Eric H
authors.initials: EH
authors.lastname: Ledet
keywords: Implantable; Passive Resonator; Sensor; Wireless