Chemical-assisted bonding of thermoplastics/elastomer for fabricating microfluidic valves.
Thermoplastics such as cyclic olefin copolymer (COC) and polymethylmethacrylate (PMMA) have been increasingly used in fabricating microfluidic devices. However, the state-of-the-art microvalve technology is a polydimethylsiloxane (PDMS)-based three-layer structure. In order to integrate such a valve with a thermoplastics-based microfluidic device, a bonding method for thermoplastics/PDMS must be developed. We report here a method to bond COC with PDMS through surface activation by corona discharge, surface modification using 3-(trimethoxysilyl)propyl methacrylate (TMSPMA), and thermal annealing. The method is also applicable to PMMA. The bonding strength between thermoplastics and PDMS was represented by the peeling force, which was measured using a method established by the International Organization for Standardization (ISO). The bonding strength measurement offered an objective and quantitative indicator for protocol optimization, as well as comparison with other PDMS-associated bonding methods. Using optimized bonding conditions, two valve arrays were fabricated in a COC/PDMS/COC device and cyclic operations of valve closing/opening were successfully demonstrated. The valve-containing devices withstood 100 psi (∼689 KPa) without delamination. Further, we integrated such valve arrays in a device for protein separation and demonstrated isoelectric focusing in the presence of valves.
Interdisciplinary Microsystems Group, Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, Florida 32611-6250, United States.
Pan
P
Gu
Ke
K
Liu
Hong
H
Chen
Toshikazu
T
Nishida
Z Hugh
ZH
Fan
D003516:Cycloparaffins / Q000737:chemistry; D004129:Dimethylpolysiloxanes / Q000737:chemistry; D020724:Elastomers / Q000737:chemistry*; D046210:Microfluidic Analytical Techniques / Q000379:methods*; D055616:Microtechnology / Q000379:methods*; D019904:Polymethyl Methacrylate / Q000737:chemistry; D011506:Proteins / Q000302:isolation & purification
D003516:Cycloparaffins; D004129:Dimethylpolysiloxanes; D020724:Elastomers; D011506:Proteins; C013830:baysilon; D019904:Polymethyl Methacrylate