**4. Conclusions**

In this chapter, the related manufacturing technologies for microfluidic chip fabrication are detailly described. Although rapid prototyping technologies for microfluidic chips, such as PDMS casting, micro machining, and 3D-printing, are well used in laboratory, the efficiency, machining accuracy and surface integrity of chips are still problematic for low-cost industrial batch production. Mass

production based on micro injection molding is important for the fabrication of plastic microfluidic chips, where multiple metal micro mold tool inserts can be used. The LIGA-like process with the characteristic of high precision replication, such as UV-LIGA, presents considerable advantages to fabricate industrial-grade mold tool inserts for the fabrication of plastic microfluidic chips. For future development direction of microfluidic chip fabrication, a hybrid tooling technology for multi-scale mold insert should be explored to combine feature from micrometer scale to nanometer scale; high aspect ratio microchannel replication is an important task, which is challenging micro injection molding; the rheological behaviors of polymer materials are worth studying in nanoscale for high-precision microinjection molding of polymeric parts. Functional precision components, such as microsensors, micropumps, and microelectrodes, should be integrated onto microfluidic chips along with the bonding process. Additionally, quality control of microfluidic chips should be highlighted, such as channel dimensions and consistency.
