Magnetic localization and sensing for biomedical devices

Participating Researchers
Current members: Felix Fischer, Dr. Liyuan Tan, Dr. Haoying Wang, Moonkwang Jeong
Former member: Dr. Christian Gletter

Small-scale robots, as well as minimally-invasive surgical tools, require precise control of their position and orientation deep in the human body. Currently, localization in surgeries heavily rely on the experience of the surgeon to navigate devices and imaging methods with radiation. This limits the efficiency, speed, and precision of the intervention, and inherently reduces the possibilities to use soft tools for surgical robots. Many state-of-the-art localization methods require cables, on-board batteries, or are simply too large for deep-tissue applications. The same challenges also apply for in-vivo sensors, where current technology is often using tissue-attenuated radio-frequencies.

To tackle these challenges, we developed small-scale magneto oscillatory localization (SMOL) [1], which utilizes a miniature magnet attached to a cantilever to form a mechanically resonant system.
The oscillating magnetic field induces unique signal shapes in magnetic sensors to localize the magnet with all degrees-of-freedom (full position and orientation), in deep tissues without signal attenuation, and with high accuracy and precision below 1 mm.
Thanks to the passive design, no batteries or wires are required, and the device can be miniaturized to millimeter-scale.
The on-board magnet furthermore enables magnetic actuation by electromagnetic coils, to form a closed-loop system with full real-time control of a robot.
Furthermore, magneto-oscillatory wireless sensing (MOWS), based on similar technology, can be used for sensing of various parameters, for example of tissue viscoelasticity [2,3], or external magnetic fields and gradients [4].

Related publications:
1) Fischer et. al. (2024): Magneto-oscillatory localization for small-scale robots, npj Robotics, 2(1), DOI
2) Fischer et. al. (2022): Wireless microprobe for mechano-sensing in viscoelastic materials, Annual International Conference on Manipulation, Automation and Robotics at Small Scales, Talk and Conference Proceedings Paper, Toronto, Canada, July 25-28
3) Fischer et. al. (2023): Free-ended linear model for a wireless mechano-sensing probe to determine viscoelastic properties, Annual International Conference on Manipulation, Automation and Robotics at Small Scales, Talk and Conference Proceedings Paper, Abu Dhabi, United Arab Emirates, October 9-13
3) Fischer et. al. (2024): Miniature magneto-oscillatory wireless sensor for magnetic field and gradient measurements, Applied Physics Letters, 125(7), DOI