Low‐voltage electroosmosis pump for stand‐alone microfluidics devices

Abstract

Two types of low-voltage electroosmosis pumps were developed using microfabrication technology for usage in handy or stand-alone applications of the micrototal analysis systems (micro-TAS) and the lab-on-a-chip. This was done by making a thin (< 1 microm) region in the flow path and by only applying voltages near this thin region using electrodes inserted into the flow path. The inserted electrodes must be free from bubble formation and be gas-tight in order to avoid pressure leakage. For these electrodes, Ag/AgCl or a gel salt bridge was used. For patterning the gel on the chip, a hydrophilic photopolymerization gel and a photolithographic technique were optimized for producing a gel with higher electric conductivity and higher mechanical strength. For high flow rate application, wide (33.2 mm) and thin (400 nm) pumping channels were compacted into a 1 mm x 6 mm area by folding. This pump achieves an 800 Pa static pressure and a flow of 415 nL/min at 10 V. For high-pressure application, a pump was designed with the thin and thick regions in series and positive and negative electrodes were inserted between them alternatively. This pump could increase the pumping pressure without increasing the supply voltage. A pump with 10-stage connections generated a pressure of 25 kPa at 10 V.

Self-Consistent Approach to Global Charge Neutrality in Electrokinetics: A Surface Potential Trap Model

“…In the past two decades, the EK effect has experienced a strong revival mainly owing to its various potential applications, e.g., an EO pump with no moving parts that can propel electrolytes and particles in the microscale [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23], as well as manipulate biological cells [24][25][26][27][28][29][30][31]. With the advent of microfluidic technology [32][33][34][35][36][37][38][39][40][41][42][43][44][45], many EK effect-based microfluidic devices have been fabricated, providing not only the opportunity to study the basic mechanisms of the EK effect, but also the push to extend its applications into many diverse interdisciplinary areas.…”

Microfluidic free-flow electrophoresis for proteomics-on-a-chip

“…Similar gels were used in microfluidic systems as so called ion-bridges or salt-bridges (e.g. used in electroosmotic pumps [55]) making it a also a suitable membrane material for µ-FFE.…”

“…These salt-bridges act as physical barriers towards the pressure driven flow but allow ions to pass in order to ensure electrical connection [55,78]. The device was used for efficient free-flow zone electrophoresis and isoelectric focusing.…”

“…An acrylamide solution of 18% acrylamide (monomer), 3% N,Nmethylenebisacrylamide (crosslinker) and 3% 2,2-dimethoxy-2-phenylacetophenone (photoinitiator) was prepared in IPA [55]. The silanized chips were filled with the monomer solution in the dark and placed in an in-house fabricated mask aligner.…”

“…The composition of acrylamide monomer, crosslinker and photoinitiator was taken from Y. Takamura et al [55] who describe high pressure EOF pumping with integrated salt-bridges. Therefore, it was assumed that the composition could also be used for the FFE chip.…”