title: Wireless, magnetic-based sensors for biomedical applications.
abstract: Wireless magnetic sensor technologies are gaining popularity in biomedical community due to their remote query nature, which allows them to be used as long-term implantable sensors. Some of these sensors are also low cost so they are suitable for use on a disposable basis. In this paper, two wireless magnetic sensors are described: the magnetoelastic sensor and the magneto-harmonic sensor. Magnetoelastic sensors are made of magnetoelastic materials that when under an AC magnetic field excitation, vibrate and resonate at their resonant frequencies. Since the resonant frequency of a magnetoelastic sensor is proportional to the mass or viscosity of the surrounding material, it has been used to detect chemical and biological targets by incorporating coatings that change mass/elasticity in response to the parameters of interest. Conversely, magneto-harmonic sensors detect parameters of interest by monitoring the change in the pattern or amplitude of the magnetic higher-order harmonic fields. Typically, a magneto-harmonic sensor consists of a magnetically soft material (sensing element) and a permanent magnet (biasing element). When energized by an AC magnetic field, the sensing element generates higher-order magnetic fields that change with the biasing field from the biasing element. By designing the sensor so the separation distance between these two elements varies with the parameters of interest, the magneto-harmonic sensor has been used for remote measurement of pressure and stress. This paper presents the operating principles and biomedical applications of these sensors.
authors: Department of Biomedical Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, USA. kgong@mtu.edu
authors: Keat Ghee
authors: KG
authors: Ong
authors: Ee Lim
authors: EL
authors: Tan
authors: Brandon
authors: B
authors: Pereles
authors: Brock
authors: B
authors: Horton
mesh_terms: D000818:Animals; D001419:Bacteria / Q000302:isolation & purification; D020811:Biomedical Technology / Q000295:instrumentation*; D015374:Biosensing Techniques / Q000295:instrumentation*; D001777:Blood Coagulation; D002417:Cattle; D019245:Compressive Strength; D004548:Elasticity; D006863:Hydrogen-Ion Concentration; D008280:Magnetics / Q000295:instrumentation*; D011312:Pressure; D013916:Thrombelastography