A miniature, nongassing electroosmotic pump operating at 0.5 V

Area of Science:

• Electrochemistry
• Materials Science
• Fluid Dynamics

Background:

• Traditional electroosmotic pumps often use platinum electrodes and high voltages, leading to water electrolysis and gas bubble formation.
• Gas bubbles can adhere to electrodes and membranes, hindering pump performance and preventing steady flow rates.
• Existing designs face challenges in maintaining consistent operation due to electrolysis byproducts.

Purpose of the Study:

• To develop a more efficient and stable electroosmotic pump by replacing conventional platinum electrodes.
• To investigate the feasibility of operating electroosmotic pumps below the water electrolysis threshold.
• To characterize the performance and efficiency of pumps utilizing silver/silver oxide electrodes.

Main Methods:

• Replaced platinum electrodes with consumed silver/silver oxide (Ag/Ag(2)O) electrodes in electroosmotic pumps.
• Operated the pumps at voltages below the 1.23 V threshold for water electrolysis.
• Measured flow rates, efficiency (water molecules per electron, water volume per joule), and power consumption.

Main Results:

• Pumps operated efficiently below 1.23 V, avoiding hydrogen and oxygen gas production.
• Achieved high efficiency with 13,000 water molecules pumped per reacted electron.
• Demonstrated a flow rate of 0.13 mL min(-1) V(-1) cm(-2) and 290 mL min(-1) W(-1) flow rate per unit power.

Conclusions:

• Silver/silver oxide electrodes enable stable and efficient electroosmotic pumping below the water electrolysis threshold.
• The proton-driven mechanism provides a reliable method for fluid transport.
• The developed pumps offer sufficient flow rates for potential applications in drug delivery systems.