Sensory Sciences Guest Lecture: Dr. Michael Christiansen, Magnetic Induction for Tracking Microrobots and Biosensing

Sensory Sciences Guest lecture by Dr. Michael Christiansen<https://hest.ethz.ch/en/department/people/organisational-units/institute-translational-medicine/responsive-biomedical-systems/personen-detail.MjQ0MTEz.TGlzdC8yODQ3LC0xMjM4MzE5ODAy.html> from Medical Microsystems Laboratory at ETH Zurich, Switzerland on

Friday, 22.11.24, 15:00

in the seminar room (00.020) of the ZMPT/MVC building, Henkestr. 91, 91052 Erlangen

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Magnetic Induction for Tracking Microrobots and Biosensing

Dr. Michael Christiansen
Senior Scientist at the Medical Microsystems Laboratory at ETH Zurich, Switzerland

Abstract:
Interest has recently grown in biomedical microrobots, microscale structures that incorporate magnetic materials to enable noninvasive control and actuation for purposes such as targeted drug delivery. One challenge associated with the control of these microrobots in physiological settings is the need for some form of feedback to indicate their position and response to applied fields. Usually, this is accomplished with optical methods or ultrasound, which suffer from limited tissue penetration, or x-ray fluoroscopy, which requires ionizing radiation and the addition of contrast agents to the microrobots. Here, I will discuss our efforts toward an alternative: using the time-changing magnetization of microrobots directly for simultaneous actuation and sensing via magnetic induction. Typical actuation frequencies of microrobots are in the range of Hz to 10s of Hz, thousands of times less than frequencies used in magnetic particle imaging, a related technique based on inductive sensing. To collect inductive signals at these unusually low frequencies, we engineer systems that can suppress background signal from the actuating field by 90 dB, isolating signals from model micromagnets that reveal information about their position and torque transfer to their surroundings.
As a separate yet methodologically connected topic, I will discuss our parallel efforts toward low cost biosensing based on inductive coils built into printed circuit boards. That work focuses on the detection of proteases, enzymes that cleave peptides and proteins, which can serve as richly informative biomarkers. Although several laboratory techniques exist for sensitively detecting proteolytic activity, our goal is to make inexpensive and easy-to-use sensors that would enable ubiquitous protease sensing with patient samples. Our latest prototype utilizes a pulsed magnetic field applied to a simple fluidic channel that has been chemically modified to ensure low nonspecific protein binding. Magnetic nanoparticles are chemically bound to a zwitterionic polymer in the channel via selectively cleavable peptides, such that their cleavage by the protease of interest releases the nanoparticles and triggers an observable change in the inductive signal.

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