Thin-Film Magnetoelastic Microsensors for Remote Query Biomedical Monitoring

Magnetoelastic thin-film sensors can be considered the magnetic analog of an acoustic bell: in response to an externally applied magnetic field impulse the sensors ring like a bell, emitting magnetic flux with a characteristic resonant frequency. The magnetic flux can be detected remotely, external to the test area, using a pick-up coil. By monitoring changes in the characteristic resonant frequency of the sensor multiple environmental parameters can be measured. In this work we report on application of magnetoelastic sensors for remote query measurement of temperature, pressure, viscosity and, in combination with a glucose-responding mass-changing polymer, in situ measurement of biological-level glucose concentrations. The advantage of using magnetoelastic sensors is that they are monitored remotely, without the need for direct physical connections such as wires or cables, nor line-of-sight alignment as needed with optical detection methods. The remote query capability allows the magnetoelastic sensors to be monitored from inside sealed, opaque containers. Depending upon the application magnetoelastic sensors can be sized from micrometer to millimeter dimensional scales, and have a material cost of approximately $0.001 allowing for their use on a disposable basis.