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A novel technique for bonding polymer substrates using PDMS-interface bonding is presented in this paper. This novel bonding technique holds promise for achieving precise, well-controlled, low temperature bonding of microfluidic channels. A thin (10-25 µm) poly(dimethylsiloxane) (PDMS) intermediate layer was used to bond two poly(methyl methacrylate) (PMMA) substrates without distorting them. Microchannel patterns were compressed on a PMMA substrate by a hot embossing technique first. Then, PDMS was spin-coated onto another PMMA bare substrate and cured in two stages. In the first stage, it was pre-cured at room temperature for 20 h to increase the viscosity. Subsequently, it was bonded to the hot embossed PMMA substrate. In the second stage, PDMS was completely cured at 90 • C for 3 h and the bonding was successfully achieved at this relatively low temperature. Tensile bonding tests showed that the bonding strength was about 0.015 MPa. Microfluidic channels with dimensions of 300 µm × 1.6 cm × 100 µm were successfully fabricated using this novel bonding method.

We present a biosensor design based on capturing the two-dimensional (2D) phase image of surface plasmon resonance (SPR). This 2D SPR imaging technique may enable parallel label-free detection of multiple analytes and is compatible with the microarray chip platform. This system uses our previously reported differential phase measurement approach, in which 2D phase maps obtained from the signal (P) and reference (S) polarizations are compared pixel by pixel. This technique greatly improves detection resolution as the subtraction step can eliminate measurement fluctuations caused by external disturbances as they essentially appear in both channels. Unlike conventional angular SPR systems, in which illumination from a range of angles must be used, phase measurement requires illumination from only one angle, thus making it well suited for 2D measurement. Also, phase-stepping introduced from a moving mirror provides the necessary modulation for accurate detection of the phase. In light of the rapidly increasing need for fast real-time detection, quantification, and identification of a range of proteins for various biomedical applications, our 2D SPR phase imaging technique should hold a promising future in the medical device market.

A novel technique for bonding polymer substrates using PDMS-interface bonding is presented in this paper. This novel bonding technique holds promise for achieving precise, well-controlled, low temperature bonding of microfluidic channels. A thin (10-25 µm) poly(dimethylsiloxane) (PDMS) intermediate layer was used to bond two poly(methyl methacrylate) (PMMA) substrates without distorting them. Microchannel patterns were compressed on a PMMA substrate by a hot embossing technique first. Then, PDMS was spin-coated onto another PMMA bare substrate and cured in two stages. In the first stage, it was pre-cured at room temperature for 20 h to increase the viscosity. Subsequently, it was bonded to the hot embossed PMMA substrate. In the second stage, PDMS was completely cured at 90• C for 3 h and the bonding was successfully achieved at this relatively low temperature. Tensile bonding tests showed that the bonding strength was about 0.015 MPa. Microfluidic channels with dimensions of 300 µm × 1.6 cm × 100 µm were successfully fabricated using this novel bonding method.