The next processing step after the oxygen plasma assisted bonding of the PDMS-mould is the chip-packaging procedure via reflow soldering of the FPGA. Mounting and soldering of the chip and the additional necessary low impedance capacitors has been realized with a standard printed circuit board manufacturing process. No special requirements for this production process were needed.
One of the critical components for integrated microfluidic devices like the Chemical microprocessor (ChµP) is an efficient interconnection to our external fluid equipment such as high performance syringe pumps and the programmable fluidic-microwell interface.
The final interconnection step of the hybrid biochips to an external fluidic handling system were achieved via PTFE (Polytetrafluoroethylene) capillary tubing (inner/outer tube diameters are 200/800 µm) of 18 and alternative 35 (see opposite picture) parallel connected high-rate etching holes in the silicon-layer and we try to fix the teflon tubes with an adhesion technique based on photoactivated industrial adhesives. It has shown again and again, that we have a couple of problems with a leak tightness, especially regarding to resistance to variations in temperature as well as organic solvents. Furthermore, the used adhesive have have a strong tendency to flow inside and block the microfluidic channels because of the capillary effect. On this account we developed a simple and versatile method to fabricate a parallel, minimal dead-volume connector using PDMS casting techniques without use of any adhesive materials.