Hello everyone, I am Purnendu, a Ph.D. student at the ATLAS Institute, University of Colorado, Boulder. I am here to present the late-breaking work “Soft Electrohydraulic Actuators for Origami-Inspired Shape changing Interfaces”. This work is done in collaboration with my co-authors Eric Acome, Christoph Keplinger, Mark D Gross, Carson Bruns, and Daniel Leithinger. We propose a new prototyping technology for origami-inspired shape-changing interfaces.
Shape-changing Interfaces have been around for a while. Traditionally they are constructed out of rigid electromechanical components. Some examples include inFORM, lineFORM, NinjaTrack, etc. However, rigid components limit the possible shape outputs.
Consequently, soft prototyping techniques have been proposed which generally rely on pneumatics, humidity, or heat for actuation.
But they also suffer from limitations like being bulky in terms of the control system and slow in shape transformation.
In this work, we present electrohydraulic actuators for origami-inspired shape-changing interfaces, which are capable of producing sharp hinge-like bends. These compliant actuators generate an immediate hydraulic force upon electrostatic activation without an external fluid supply source. They are silent and fast in operation and can be fabricated with commodity materials.
Here, we present the general design of these actuators. It consists of oil-filled flexible plastic pouches partially covered with flexible electrodes on both sides as shown in Figure B(i).
When a DC voltage of the order of 8kV is applied across the pair of flexible electrodes, they tend to zip together, shown in figure B(ii). This zipping motion of the electrodes displaces the fluid between them to the surrounding volume resulting in shape change, as in figure B (iii). These pouches are further attached with strain limiting layers to create sharp hinge-like bends. A thin insulating layer between the electrodes and the strain limiting layer is necessary for failure-free operation of the actuators, shown in Figure A.
These actuators are compliant, silent, and fast in operation. They generate an immediate hydraulic force upon electrostatic activation without an external fluid supply source.
We also present a design tool to aid the design and fabrication of these actuators. A user can load the predefined actuator geometry and adjust the parameters according to their needs. Afterward, the tool allows the user to visualize the shape change
and export fabrication files. These actuators can be fabricated with commodity materials and easily available tools.
We begin by heat sealing two pieces of polymer sheet using a custom modified heat of a CNC machine to create the outer geometry of the pouch. We leave a small input port for oil filling.
Afterward, we manually fill the pouch with silicone oil using syringes and seal the input port.
We then paint the flexible electrodes using conductive carbon paint and eventually, trim the excess polymer sheet.
Here, we show the DC power supply used to activate these actuators powered by a lithium polymer battery similar to the ones used in smartphones these days. Though the activation voltage is of the order of kilovolts, this power supply ensures very low current consumption making these actuators human safe.
These actuators can bend like a hinge and actuate light as well as heavy objects. Here we show two example prototypes as an actuating box and an actuating origami bird.
In conclusion, we presented soft electrohydraulic actuators for origami-inspired shape change. These actuators offer novel features like : Compact Design, Rapid actuation, Silent Operation, and Easy Fabrication.
During the process of developing this late-breaking work, we also realized a number of limitations that open up possibilities for future work, like we realize the need for the user evaluation of the prototypes.
We also think this work opens up possibilities for other new kinds of soft electrohydraulic actuator geometries with novel functions. There is also a possibility of adding a simulation feature in the software tool as well as lowering the voltage of activation by choosing better materials as well as insulating the electrodes.
Thank you so much for being here and listening about this work. I will be happy to take questions.