2019-Self-Biased, Mass-Loaded Miniaturized Magnetoelastic Resonators

magnetoelastic resonatorminiaturizedpassive sensor
  • magnetoelastic resonator
  • miniaturized
  • passive sensor


Magnetoelastic resonators are versatile, widely used sensors. Automobile, packaging, semiconductor, and many other industries use wireless magnetoelastic sensors in their processes. Miniaturizing these sensors can open up even more applications in the field of small or sensitive systems. However, it is difficult to reduce sensor dimensions while preserving sensor function and signal quality. In order to maintain sensor function at decreased sizes, a novel approach for miniaturization is presented. This technique aims to preserve sensor resonant frequency and signal strength to be compatible with existing systems by combining two methods: 1) a strategic mass placement for tuning the resonant frequency of the sensor, and 2), self-biasing the sensor for improved signal strength. These techniques were interrogated using finite element analysis, and a prototype sensor was fabricated and tested experimentally. Test results showed that the prototype miniature sensor had comparable signal quality to a sensor twice its size, and was compatible with standard signal receiving systems.

Miniaturization Concept

The key issue with miniaturizing magnetoelastic resonators is the increase in resonant frequency with decreasing length scales. Drastic changes in resonant frequency make the miniaturized sensor incompatible with the standard receiver system, complicating system setup and incurring unnecessary costs. Therefore, strategic placement of mass loads along the miniaturized sensor is used to decrease the resonant frequency to match standard ranges. These masses are then magnetized, and self-biased to cause a permanent DC magnetic field around the sensor. The DC field allows stronger signal quality despite the reduced sizes. By combining these two methods, the miniaturized sensor gives comparable resonant frequencies and signal quality to a standard size sensor. Magnetoelastic resonators are highly versatile, capable of measuring temperature, pressure, density, viscosity, and chemical/biological agents wirelessly. A miniaturized sensor that still maintains high signal quality can improve on existing application modes by reducing the deadweight/volume, and also newly impact sensing schemes for small, sealed environments.




Decrease volume and weight while maintaining signal quality

Reduce weight impact on the system


Reduced dead volume for sensing within sealed environments

Resonance frequency matched to receiver system for ease of integration

Passive sensor

Simple miniaturization concept

The miniaturized device is widely applicable in many fields

Potential Applications:

Miniaturize magnetoelastic resonance sensors for temperature, pressure

Sensing liquid viscosity and density in sealed chambers

Sensing fluid flow velocity in small cavities/channels

Chemical/biological sensing implemented in small detection platforms

Integration in portable and/or other compact systems (i.e. tablets)

Research tool for small volume systems assembly and analysis

Surgical implants or implantable devices

Wireless sensing for sealed environments

Contact Information:

  • Name: Joohee Kim
  • Title :
  • Department :
  • Email : jooheek@umich.edu
  • Phone : (734) 647-5730
  • Address :