The effect of pre-polymer/cross-linker storage on the elasticity and reliability of PDMS microfluidic devices

Polydimethylsiloxane (PDMS) is a commonly used material in biomedical engineering (Sollier et al. in Lab Chip 11(22):3752–3765, 2011 ; Palchesko et al. in PLoS ONE 7(12):e51499, 2012 ; Berthier et al. in Lab Chip 12(7):1224–1237, 2012 ). Its elastic nature makes PDMS especially attractive for microf...

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Bibliographic Details
Published in:Microfluidics and nanofluidics 2017-07, Vol.21 (7), p.1, Article 117
Main Authors: Agaoglu, Sevda, Robles, Michael C., Smith, Connor D., Quake, Stephen R., Araci, I. Emre
Format: Article
Language:English
Subjects:
Actuation
Analytical Chemistry
Biomedical engineering
Biomedical Engineering and Bioengineering
Biomedical materials
Chips
Components
Crosslinking
Defects
Deflection
Elastic properties
Elasticity
Engineering
Engineering Fluid Dynamics
Exposure
Humidity
Large scale integration
Mechanical properties
Modulus of elasticity
Nanotechnology and Microengineering
Photosystem I
Polydimethylsiloxane
Polymers
Pressure
Properties
Reliability
Research Paper
Scientific apparatus & instruments
Silicone resins
Storage
Storage conditions
Technology
Valves
Yields
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Summary:Polydimethylsiloxane (PDMS) is a commonly used material in biomedical engineering (Sollier et al. in Lab Chip 11(22):3752–3765, 2011 ; Palchesko et al. in PLoS ONE 7(12):e51499, 2012 ; Berthier et al. in Lab Chip 12(7):1224–1237, 2012 ). Its elastic nature makes PDMS especially attractive for microfluidic large-scale integration (mLSI) technology where micromechanical valves are actuated by deflecting a PDMS membrane under pressure. Therefore, understanding and control of PDMS elastic properties have commercial and scientific significance. In this study, we have investigated the effects of pre-polymer/cross-linker storage conditions on the mechanical properties of cured PDMS films as well as on microfluidic devices. We have showed that when the uncured components of PDMS are exposed to different humidity conditions, the elasticity of the PDMS changes and this is revealed as a change in the Young’s modulus of the cured PDMS. The high humidity (~85%) exposure for 24 h causes PDMS to become softer as confirmed by a significant decrease in the Young’s modulus values from 1.2 to 0.9 MPa. Furthermore, as the PDMS is exposed to high humidity conditions for longer periods (72 h), the Young’s modulus decreases down to 0.7 MPa. We found that exposing only the pre-polymer PDMS (Part A) to humid air does not alter the cured PDMS properties significantly, whereas exposure of the cross-linker (Part B) is responsible for the elasticity change. We have strictly controlled the storage humidity to build more reliable microfluidic chips using mLSI. As a result, actuation pressure of valves (10 psi) and defects of devices (in 
ISSN:1613-4982
1613-4990
DOI:10.1007/s10404-017-1953-0