Published: March 31, 2022

This invention maps changes in magnetic field strength to changes in actuator shape without seeing noise from the actuator or reducing performance.


RobotThe field of soft robotics has been rapidly gaining traction due to the deformable and compliant nature of the structural components. These qualities allow for improved adaptability - when compared to the capabilities of conventional, rigid robots - in unstructured environments. In the domain of both traditional and soft robotics, integrating a reliable sensing mechanism with the actuation method is necessary for the robot to interact with its environment. Therefore, having an on-board sensing mechanism is necessary for creating compact, untethered systems.


To address some of the shortcomings of current sensing methods used for electrohydraulic actuators, such as HASELs, researchers at the University of Colorado explored the idea of using a magnetic sensing approach to measure the change in shape, specifically linear displacement, of a folded HASEL actuator. These actuators are driven by a very low current, which emits a negligible magnetic field. By sandwiching the actuator between an off-the-shelf magnetometer and a magnetic component, as shown in the figure below, they were able to map changes in magnetic field strength to changes in the actuator shape without seeing any noise from the actuator or reduction in performance.


  • High resolution of 0.1 mm
  • Fast sampling rates up to 1 kHz
  • Modular design; easy to scale up for larger systems
  • Elegant fabrication process
  • Clean signal; decoupled from HV noise


  • Soft continuum robots
  • Grippers and manipulators
  • Terrain detection for mobile robots
  • Embedded sensing for orthotics and prosthetics
  • Soft robotic platforms with low current usage


Nicole Forsberg:

Diagram of actuator