title: Elementary Implantable Force Sensor: For Smart Orthopaedic Implants.
abstract: Implementing implantable sensors which are robust enough to maintain long term functionality inside the body remains a significant challenge. The ideal implantable sensing system is one which is simple and robust; free from batteries, telemetry, and complex electronics. We have developed an elementary implantable sensor for orthopaedic smart implants. The sensor requires no telemetry and no batteries to communicate wirelessly. It has no on-board signal conditioning electronics. The sensor itself has no electrical connections and thus does not require a hermetic package. The sensor is an elementary L-C resonator which can function as a simple force transducer by using a solid dielectric material of known stiffness between two parallel Archimedean coils. The operating characteristics of the sensors are predicted using a simplified, lumped circuit model. We have demonstrated sensor functionality both in air and in saline. Our preliminary data indicate that the sensor can be reasonably well modeled as a lumped circuit to predict its response to loading.
authors.affiliation: Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, New York, USA.
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Wachs
authors.affiliation: Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York, USA.
authors.forename: David
authors.initials: D
authors.lastname: Ellstein
authors.affiliation: Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, New York, USA.
authors.forename: John
authors.initials: J
authors.lastname: Drazan
authors.affiliation: Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, New York, USA.
authors.forename: Colleen P
authors.initials: CP
authors.lastname: Healey
authors.affiliation: Division of Orthopaedic Surgery, Albany Medical College, Albany, New York, USA.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Uhl
authors.affiliation: Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York, USA.
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Connor
authors.affiliation: Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, New York, USA.
authors.forename: Eric H
authors.initials: EH
authors.lastname: Ledet
keywords: Force; Implantable Sensor; Orthopaedic Surgery; Passive Resonator; Pressure