Bubble‐free electrokinetic flow with propylene carbonate

Sritharan, Deepa; Chen, Abraham Simpson; Aluthgama, Prabhath; Naved, Bilal A.; Smela, Elisabeth

doi:10.1002/elps.201400443

Cited by 5 publications

(12 citation statements)

References 43 publications

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“…The pumping liquid for electroosmosis was propylene carbonate (PC) (anhydrous 99.7%, Sigma-Aldrich, St. Louis, MO, USA, 310328). The PC was stored in a glove box with an argon atmosphere because exposure to ambient moisture causes irreversible chemical degradation [8]. The device fabrication and experiments were, however, performed under atmospheric conditions, not in a glove box.…”

Section: Methodsmentioning

confidence: 99%

“…Typically, water is used in EO pumps due to its high polarity, but in water, electrolysis causes depletion of the pumping liquid, changes in pH, and evolution of gas bubbles, resulting in irreproducible pumping, low actuation pressure, and device failure. In this paper, we used propylene carbonate (PC) as the pumping liquid because it exhibits bubble-free operation up to kV [8,56]. The zeta potential for both water and PC in PDMS is negative [8]: fluid moves from the positive electrode toward the negative electrode, indicating that the mobile charges at the walls are positive (cations).…”

Section: Device Designmentioning

confidence: 99%

“…Electroactive and stimuli-responsive polymer actuators span a wide range of materials and performance (see recent reviews [1,2,3] and conference proceedings [4,5,6]). The electroosmotic actuator presented here makes use of a different actuation mechanism, based on microfluidics [7,8].…”

Section: Introductionmentioning

confidence: 99%

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Fabrication of a Miniature Paper-Based Electroosmotic Actuator

Sritharan

Smela

2016

Polymers

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A voltage-controlled hydraulic actuator is presented that employs electroosmotic fluid flow (EOF) in paper microchannels within an elastomeric structure. The microfluidic device was fabricated using a new benchtop lamination process. Flexible embedded electrodes were formed from a conductive carbon-silicone composite. The pores in the layer of paper placed between the electrodes served as the microchannels for EOF, and the pumping fluid was propylene carbonate. A sealed fluid-filled chamber was formed by film-casting silicone to lay an actuating membrane over the pumping liquid. Hydraulic force generated by EOF caused the membrane to bulge by hundreds of micrometers within fractions of a second. Potential applications of these actuators include soft robots and biomedical devices.

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Section: Methodsmentioning

confidence: 99%

Section: Device Designmentioning

confidence: 99%

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Fabrication of a Miniature Paper-Based Electroosmotic Actuator

Sritharan

Smela

2016

Polymers

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“…Apart from depleting the pumping liquid, the evolved gases form bubbles, which adhere to the channel walls and block the electrodes, interrupting current flow and causing pump failure. We have recently demonstrated [18] that EO can be performed with an electrochemically stable polar organic liquid [19], propylene carbonate (PC), as the pumping fluid to replace water for bubble-free electroosmosis. PC is nonvolatile [20] and has a high dielectric constant of 64 [20].…”

Section: Equationmentioning

confidence: 99%

Stable electroosmotically driven actuators

et al. 2013

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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/d 2 , 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.

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“…In analogy to botany where changes in hydrostatic cell pressure, e.g., water content, cause movement of plants, these devices were named 'nastic actuators.' Only recently the same group published a further development, where propylene carbonate (PC) was used instead of water in order to avoid bubble generation and pressure fluctuations which allowed the realization of a fully sealed microfluidic hydraulic actuator [100].…”

Section: Microstructures Based On Pdmsmentioning

confidence: 99%

Stimulus-active polymer actuators for next-generation microfluidic devices

Hilber

2016

Appl. Phys. A

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Microfluidic devices have not yet evolved into commercial off-the-shelf products. Although highly integrated microfluidic structures, also known as lab-on-a-chip (LOC) and micrototal-analysis-system (lTAS) devices, have consistently been predicted to revolutionize biomedical assays and chemical synthesis, they have not entered the market as expected. Studies have identified a lack of standardization and integration as the main obstacles to commercial breakthrough. Soft microfluidics, the utilization of a broad spectrum of soft materials (i.e., polymers) for realization of microfluidic components, will make a significant contribution to the proclaimed growth of the LOC market. Recent advances in polymer science developing novel stimulus-active soft-matter materials may further increase the popularity and spreading of soft microfluidics. Stimulus-active polymers and composite materials change shape or exert mechanical force on surrounding fluids in response to electric, magnetic, light, thermal, or water/solvent stimuli. Specifically devised actuators based on these materials may have the potential to facilitate integration significantly and hence increase the operational advantage for the end-user while retaining costeffectiveness and ease of fabrication. This review gives an overview of available actuation concepts that are based on functional polymers and points out promising concepts and trends that may have the potential to promote the commercial success of microfluidics.

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Bubble‐free electrokinetic flow with propylene carbonate

Cited by 5 publications

References 43 publications

Fabrication of a Miniature Paper-Based Electroosmotic Actuator

Fabrication of a Miniature Paper-Based Electroosmotic Actuator

Stable electroosmotically driven actuators

Stimulus-active polymer actuators for next-generation microfluidic devices

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