@phdthesis{Gertler26-PHD-Actuators,
  title = {Modeling, Fabricating, and Evaluating Synergistic Soft‑Rigid Actuators},
  abstract = {Soft actuators offer lightweight, compliant, and safe alternatives to traditional mechanisms, but they often incur complicated actuation schemes, bulky support systems, and limited functionality when made solely from soft materials. Soft‑rigid designs that integrate rigid elements into primarily soft bodies are common, yet the potential of those rigid parts to shape actuation behavior without compromising the overall softness remains underexplored, and fabrication practices often lack reproducibility. 
  
  This thesis presents two case studies of synergistic hybrid actuation systems that utilize the complementary roles of soft and rigid components to dictate temporal and spectral behavior in response to simple input commands. Between the soft and hard components, one is typically active, while the other is passive.
  
  The first case study implements a soft-active/rigid-passive approach for the medical robotics application of endoluminal locomotion. A thin hyperelastic balloon encased in an inextensible sleeve is coupled with a thicker, non-encased balloon on a single fluid supply to serve as front and rear anchors, respectively. 
  
  Geometry and material selection reshape the pressure-stretch response so the rear anchor inflates and deflates before the front anchor, enabling asymmetric sequencing useful for peristaltic locomotion inside a lumen. Numerical simulation and experiments validate the characteristic curves of dip-molded balloons and alternating anchoring in rigid tubes. The approach can be extended to generate actuation patterns for sequential haptic feedback and other robotic applications.
  
  The second case study applies a soft-passive/rigid-active strategy in the domain of fingertip haptic actuation. A dip‑molded silicone sheath with embedded miniature magnets, excited by a single air‑core coil, produces localized, rich vibrotactile feedback. Simulations, mechanical measurements, and user experiments with a single-magnet design show consistent frequency‑dependent behavior and strong perceptual salience. In follow-on work, various dual‑magnet arrangements were also simulated, fabricated, and thoroughly evaluated. Classification tests indicate that frequency content is more important for perception than magnet orientation, while a realism‑rating experiment supports the feasibility of audio-driven simple commands for realistic haptic feedback. The device is demonstrated on the fingertip in virtual reality and could be adapted for other body locations for navigation, rehabilitation, or related applications.
  
  Together, these studies provide design rules, a simulation-fabrication-validation workflow, and reproducible fabrication practices for soft-rigid hybrid actuators that realize desired mechanical outputs from minimal actuation commands. The methods and findings generalize to other soft actuators and have potential applications in domains such as medical devices, wearable technologies, and soft sensing.},
  degree_type = {PhD},
  school = {University of Stuttgart},
  address = {Stuttgart, Germany},
  month = feb,
  year = {2026},
  note = {Faculty of Engineering Design, Production Engineering and Automotive Engineering},
  author = {Gertler, Ifat},
  month_numeric = {2}
}