TY - JOUR
T1 - Surface Modification of Glass/PDMS Microfluidic Valve Assemblies Enhances Valve Electrical Resistance
AU - Wang, Xuemin
AU - Agasid, Mark T.
AU - Baker, Christopher A.
AU - Aspinwall, Craig A.
N1 - Funding Information:
This research was supported by National Institutes of Health via the National Institute of Biomedical Imaging and Bioengineering under Grant No. 2R01EB007047 and 1R21EB022297 and the National Institute of General Medical Sciences under Grant No. 1R01GM095763. The content is solely the responsibility of the authors and does not necessarily represent the official views of the sponsors.
Publisher Copyright:
Copyright © 2019 American Chemical Society.
PY - 2019/9/18
Y1 - 2019/9/18
N2 - Microfluidic instrumentation offers unique advantages in biotechnology applications including reduced sample and reagent consumption, rapid mixing and reaction times, and a high degree of process automation. As dimensions decrease, the ratio of surface area to volume within a fluidic architecture increases, which gives rise to some of the unique advantages inherent to microfluidics. Thus, manipulation of surface characteristics presents a promising approach to tailor the performance of microfluidic systems. Microfluidic valves are essential components in a number of small volume applications and for automated microfluidic platforms, but rigorous evaluation of the sealing quality of these valves is often overlooked. In this work, the glass valve seat of hybrid glass/PDMS microfluidic valves was surface modified with hydrophobic silanes, octyldimethylchlorosilane (ODCS) or (tridecafluoro-1,1,2,2-tetrahydrooctyl)dimethylchlorosilane (PFDCS), to investigate the effect of surface energy on electrical resistance of valves. Valves with ODCS- or PFDCS-modified valve seats both exhibited >70-fold increases in electrical resistance (>500 Gω) when compared to the same valve design with unmodified glass valve seats (7 ± 3 Gω), indicative of higher sealing capacity. The opening times for valves with ODCS- or PFDCS-modified valve seats was ca. 5× shorter compared to unmodified valve seats, whereas the closing time was up to 8× longer for modified valve seats, although the total closing time was ≤1.5 s, compatible with numerous microfluidic valving applications. Surface modified valve assemblies offered sufficient electrical resistance to isolate sub-pA current signals resulting from electrophysiology measurement of α-hemolysin conductance in a suspended lipid bilayer. This approach is well-suited for the design of novel microfluidic architectures that integrate fluidic manipulations with electrophysiological or electrochemical measurements.
AB - Microfluidic instrumentation offers unique advantages in biotechnology applications including reduced sample and reagent consumption, rapid mixing and reaction times, and a high degree of process automation. As dimensions decrease, the ratio of surface area to volume within a fluidic architecture increases, which gives rise to some of the unique advantages inherent to microfluidics. Thus, manipulation of surface characteristics presents a promising approach to tailor the performance of microfluidic systems. Microfluidic valves are essential components in a number of small volume applications and for automated microfluidic platforms, but rigorous evaluation of the sealing quality of these valves is often overlooked. In this work, the glass valve seat of hybrid glass/PDMS microfluidic valves was surface modified with hydrophobic silanes, octyldimethylchlorosilane (ODCS) or (tridecafluoro-1,1,2,2-tetrahydrooctyl)dimethylchlorosilane (PFDCS), to investigate the effect of surface energy on electrical resistance of valves. Valves with ODCS- or PFDCS-modified valve seats both exhibited >70-fold increases in electrical resistance (>500 Gω) when compared to the same valve design with unmodified glass valve seats (7 ± 3 Gω), indicative of higher sealing capacity. The opening times for valves with ODCS- or PFDCS-modified valve seats was ca. 5× shorter compared to unmodified valve seats, whereas the closing time was up to 8× longer for modified valve seats, although the total closing time was ≤1.5 s, compatible with numerous microfluidic valving applications. Surface modified valve assemblies offered sufficient electrical resistance to isolate sub-pA current signals resulting from electrophysiology measurement of α-hemolysin conductance in a suspended lipid bilayer. This approach is well-suited for the design of novel microfluidic architectures that integrate fluidic manipulations with electrophysiological or electrochemical measurements.
KW - electrical resistance
KW - electrochemical properties
KW - microfluidic valve
KW - surface energy
KW - surface modification
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U2 - 10.1021/acsami.9b12342
DO - 10.1021/acsami.9b12342
M3 - Article
C2 - 31496217
AN - SCOPUS:85072509714
SN - 1944-8244
VL - 11
SP - 34463
EP - 34470
JO - ACS Applied Materials and Interfaces
JF - ACS Applied Materials and Interfaces
IS - 37
ER -