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UEC Int’l Mini-Conference No.54 19

Multi-DOF Soft Robotic Module Based on an Integrated Electrohydrodynamic

Pump

Ahmed ROMAN*, Jun SHINTAKE
Department of Mechanical and Intelligent Systems Engineering
The University of Electro-Communications, Tokyo, Japan

Keywords: Soft Robotics, Electrohydrodynamic (EHD) Pump, Fluidic Actuation, Multi-DOF Actuator, Modular Robotics

1. Introduction modulating the voltage to each domain, the pump generates a
The field of soft robotics, which leverages compliant materials to create controllable pressure vector. This selectively pressurizes the foam
adaptable and safe machines, has seen significant growth. Many of segments, causing the output plate to tilt (pitch and roll) or lift (heave),
these systems are driven by fluidic actuation; however, this approach is achieving 3-DOF motion from a compact, modular unit.
often constrained by its reliance on bulky, noisy, and power-intensive 3. Results
external components like air compressors. This "tether problem" The research plan involves a two-stage experimental validation. First,
severely limits the portability, scalability, and autonomy of soft robots, the standalone tri-domain EHD pump will be characterized to measure
hindering their transition from laboratory environments to real-world its maximum pressure, flow rate, and response time as a function of
applications. [1] applied voltage. Subsequently, the fully assembled 3-DOF module will
Electrohydrodynamic (EHD) pumps offer a transformative alternative. be tested to quantify its mechanical performance, including
By using an electric field to induce fluid motion via ion drag, EHD displacement angle, output force, and actuation speed.
pumps operate silently with no moving parts, making them inherently 4. Discussion
compact, scalable, and ideal for integration. While researchers have To demonstrate its versatility, the module will be integrated into two
successfully demonstrated soft actuators powered by integrated EHD distinct robotic systems: a multi-jointed soft manipulator and an
pumps, these implementations have been almost exclusively limited to untethered underwater swimming robot. Success in these applications
single-degree-of-freedom (single-DOF) motion, such as simple will validate the module as a general-purpose building block for
bending or expansion. [2] advanced, untethered soft robotic systems. (Fig. 2)
This work addresses this critical research gap by developing a novel,
fully integrated 3-DOF soft robotic actuator module. By engineering a
Manipulator Eel Robot
single EHD pump capable of multi-zone fluidic control, this research Robot Head
aims to unlock the full potential of EHD technology for creating
compact, versatile, and autonomous soft robotic systems.
Body
2. Method
The core of this work is a novel EHD pump design featuring rounded
interdigitated electrodes partitioned into three independently eft Up Down Right Fin
controllable domains (Fig. 1). This multi-domain configuration allows
Fig. 2. Schematics of soft robots integrated with 3-
for directional fluidic control from a single pump structure. The pump DOF actuator modules.
is fabricated using a simple, low-cost, layer-by-layer process with laser-
cut dielectric (VHB 4905) and conductive (ARcare 90366) film and 5. Conclusion
This research presents a clear pathway to overcoming the functional
limitations of current EHD-powered soft actuators. By developing an
integrated 3-DOF module, this work moves beyond simple single-axis
motion and enables more dexterous and versatile soft robots. The
modular and scalable design is a foundational step toward creating new
classes of compact, silent, and autonomous machines for manipulation,
exploration, and human-assistive applications.
Fig. 1. (a) An EHD pump with interdigitated electrodes. (b) Rounded References
interdigitated electrode design with three domains proposed in this
study. (c) Concept of 3-DOF actuator module. [1] Cacucciolo, Vito, et al. "Stretchable pumps for soft machines."
Nature 572.7770 (2019): 516-519.
uses Novec 7300 as the dielectric working fluid. [2] Peng, Yanhong, et al. "A review on electrohydrodynamic (EHD)
To create the 3-DOF actuator, soft open-cell foam structures are pump." Micromachines 14.2 (2023): 321.
attached to each of the three electrode domains. A rigid plate mounted
on the foam serves as the mechanical output. By independently

*The author is supported by (SESS) MEXT Scholarship