Improving electrokinetic microdevice stability by controlling electrolysis bubbles

Abstract

The voltage-operating window for many electrokinetic microdevices is limited by electrolysis gas bubbles that destabilize microfluidic system causing noise and irreproducible responses above ∼3 V DC and less than ∼1 kHz AC at 3 Vpp. Surfactant additives, SDS and Triton X-100, and an integrated semipermeable SnakeSkin® membrane were employed to control and assess electrolysis bubbles from platinum electrodes in a 180 by 70 μm, 10 mm long microchannel. Stabilized current responses at 100 V DC were observed with surfactant additives or SnakeSkin® barriers. Electrolysis bubble behaviors, visualized via video microscopy at the electrode surface and in the microchannels, were found to be influenced by surfactant function and SnakeSkin® barriers. Both SDS and Triton X-100 surfactants promoted smaller bubble diameters and faster bubble detachment from electrode surfaces via increasing gas solubility. In contrast, SnakeSkin® membranes enhanced natural convection and blocked bubbles from entering the microchannels and thus reduced current disturbances in the electric field. This data illustrated that electrode surface behaviors had substantially greater impacts on current stability than microbubbles within microchannels. Thus, physically blocking bubbles from microchannels is less effective than electrode functionalization approaches to stabilize electrokinetic microfluidic systems.

Template-Assisted Electrodeposition of Fe-Ni-Co Nanowires: Effects of Electrolyte pH and Sodium Lauryl Sulfate

“…[34][35][36] In addition to influencing bubble behavior, SLS can also be absorbed on the cathode surface. Gomez et al 37 found that SLS helped to render Zn electrodeposits more crystalline than other additives due to the larger overpotential evident in changes of voltammetry curves attributed to SLS adsorption.…”

Platinum electrode modification: Unique surface carbonization approach to improve performance and sensitivity

“…This PBS microfluidic system previously demonstrated electrolysis bubble generation ; thus, electrode electrolysis reactions occur concurrent with carbon adsorption. During current measurements, electrolysis of water generates oxygen and hydrogen gas bubbles at the anode and cathode electrode surfaces, respectively .…”

“…Platinum wires were cut via scalpel and bent by tweezers to immerse 2 mm into each reservoir. General‐purpose epoxy (Henkel Corporation, Rocky Hill, CT, USA) attached platinum wire electrodes to a photolithographically fabricated PDMS microfluidic layer, as previously described .…”

“…Triton X‐100 attenuates electrolysis bubble effects that destabilize current responses by facilitating formation of smaller bubbles. It was shown that 320 μM Triton X‐100 does not compromise RBC membrane integrity .…”

Modeling the trajectory of microparticles subjected to dielectrophoresis in a microfluidic device for field flow fractionation

“…(7) is satisfied by all DEP-FFF microdevices handling microparticles. Moreover, operation at high frequencies is advised in order to avoid corrosion of electrodes as well as gas generation at the interface between the electrode and the medium (Voldman, 2006); a recent work, Lee et al (2014), suggests addition of surfactants for mitigating gas generation in microfludic devices. Operation at high frequencies implies that the time period associated with the electric potential is extremely small thereby allowing for assuming it to be a constant, specifically the time averaged electric potential, i.e.…”