In order to use a micro ultrasonic bonding method to package polymer microfluidic chips

an auxiliary microstructure named micro energy director is designed and fabricated on two sides of the microchannel by a selective bonding method in this paper. A hot embossing method is adopted to fabricate this newly designed Polymethyl Methacrylate(PMMA) substrate containing both convex micro energy directors and concave microchannels

then a complex silicon mold is designed and fabricated by the multi-photolithography and wet etching. By the Taguchi method

the optimized parameters for hot embossing are obtained. Experimental results show that the optimized embossing temperature is 15-20 ℃ higher than that of the simply replicate concave microstructure

since concave and convex micro structures are formed simultaneously. With the optimized parameters in an embossing temperature of 140 ℃

holding time of 300 s

and an embossing pressure of 1.65 MPa

the accuracy of replication can be up to 99%.