The Research Of Sealing Micro/Nano Fluidic Channels Based On SU-8Resist

Sealing of micro/nano fluidic channels is the key to fabricate the micro/nanofluidic system, but how to seal them with high precision, low cost, simple andquick way has become an important problem that should be solved in time. In thispaper, we put forward two kinds of innovative technology in sealing the polymerSU-8trench structure on the basis of summarizing the existing channel sealingtechnology, which are Reversal Thermal Bonding and capillary-pressure balance.We also analysis and explore the fabricating process and sealing mechanism aboutthese two technologies.Reversal thermal bonding using the feature of UV tape that adhesive force will bechanged after UV exposure obtain the SU-8trench structure on the UV tape by pouringtransfer printing technique, and implement twice transfer process of SU-8trenchstructure. The flexibility of UV tape make the SU-8trenches and the encapsulation layerof Si substrate fit tightly, which is different from the previous method that fabricate thetrench structure on a rigid substrate and then sealing. By changing the thickness of theencapsulation, we obtained different size of nanochannels and established the linearrelationship between the thickness of the encapsulation layer and the size of thenanochannels. Based on the simulation of the filling mechanism of SU-8resist using thefinite element, we analyzed the role of the capillary force during the bonding process.Capillary-pressure balance using the principle of SU-8resist’s contact wire willdelay in the flow process to seal the trenches. The trapped air will be compressed bythe capillary force, and air infiltrate from the no-curing SU-8resist in this process,which will lead to an equilibrium state between increasing pressure of the trapped airand capillary force eventually. The size of the SU-8trenches will have a great effect onthe shape of nanochannels. If the aspect ratio of SU-8trench is big, it would be ameniscus channel, and if it is small, it would be a circular channel, and we also usefinite element method to simulate the forming mechanism of the two channels.