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Proceedings Paper

Stable electroosmotically driven actuators
Author(s): Deepa Sritharan; Mylene Motsebo; Julia Tumbic; Elisabeth Smela
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Paper Abstract

We have previously presented “nastic” actuators based on electroosmotic (EO) pumping of fluid in microchannels using high electric fields for potential application in soft robotics. In this work we address two challenges facing this technology: applying EO to meso-scale devices and the stability of the pumping fluid. The hydraulic pressure achieved by EO increases with as 1/d2, where d is the depth of the microchannel, but the flow rate (which determines the stroke and the speed) is proportional to nd, where n is the number of channels. Therefore to get high force and high stroke the device requires a large number of narrow channels, which is not readily achievable using standard microfabrication techniques. Furthermore, for soft robotics the structure must be soft. In this work we present a method of fabricating a three-dimensional porous elastomer to serve as the array of channels based on a sacrificial sugar scaffold. We demonstrate the concept by fabricating small pumps. The flexible devices were made from polydimethylsiloxane (PDMS) and comprise the 3D porous elastomer flanked on either side by reservoirs containing electrodes. The second issue addressed here involves the pumping fluid. Typically, water is used for EO, but water undergoes electrolysis even at low voltages. Since EO takes place at kV, these systems must be open to release the gases. We have recently reported that propylene carbonate (PC) is pumped at a comparable rate as water and is also stable for over 30 min at 8 kV. Here we show that PC is, however, degraded by moisture, so future EO systems must prevent water from reaching the PC.

Paper Details

Date Published: 9 April 2013
PDF: 12 pages
Proc. SPIE 8687, Electroactive Polymer Actuators and Devices (EAPAD) 2013, 86872C (9 April 2013); doi: 10.1117/12.2009048
Show Author Affiliations
Deepa Sritharan, Univ. of Maryland, College Park (United States)
Mylene Motsebo, Univ. of Maryland, College Park (United States)
Julia Tumbic, Univ. of Maryland, College Park (United States)
Elisabeth Smela, Univ. of Maryland, College Park (United States)


Published in SPIE Proceedings Vol. 8687:
Electroactive Polymer Actuators and Devices (EAPAD) 2013
Yoseph Bar-Cohen, Editor(s)

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