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  • Open Access

Bifurcation-based mechanical sensing of microchannels using microrobots

Andrew Bickerdike

Joseph Páez Chávez

Yang Liu*

Antoine Ferreira

  • Exeter Small-Scale Robotics Laboratory, Engineering Department, University of Exeter, Exeter EX4 4QF, United Kingdom

  • Center for Applied Dynamical Systems and Computational Methods (CADSCOM), Faculty of Natural Sciences and Mathematics, Escuela Superior Politécnica del Litoral, P.O. Box 09-01-5863, Guayaquil, Ecuador and Center for Dynamics, Department of Mathematics, TU Dresden, D-01062 Dresden, Germany

  • Exeter Small-Scale Robotics Laboratory, Engineering Department, University of Exeter, Exeter EX4 4QF, United Kingdom

  • *Contact author: y.liu2@exeter.ac.uk
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Phys. Rev. E 112, 045405 – Published 10 October, 2025

DOI: https://doi.org/10.1103/zrcy-c36h

Abstract

We present a minimally invasive method for probing the mechanical properties of soft-walled microchannels by analyzing the bifurcations in the periodic motion of a magnetically actuated microrobot. Under oscillatory magnetic excitation, the microrobot undergoes transitions, including grazing and fold bifurcations, during wall interactions that are highly sensitive to local stiffness and damping. Experiments and numerical continuation reveal consistent bifurcation shifts across channels of varying compliance, enabling mechanical characterization through frequency-dependent response. A piecewise-smooth dynamical model incorporating fluid damping and compliant boundaries captures the observed behaviors. This bifurcation-based approach leverages dynamic signatures to provide a sensitive method for mechanical sensing in simplified confined environments. It lays the groundwork for future extensions towards applications in tissue diagnostics, vascular health monitoring, and soft material characterization.

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Phys. Rev. E 112, 045405– Published 10 October, 2025
  • Received 10 May 2025
  • Accepted 15 September 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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