Integrated polymethylmethacrylate - polydimethylsiloxane devices for microfluidic applications

Polymeric materials are widely used in manufacturing of microfluidic devices, and polydimethylsiloxane (PDMS) is a commonly used polymeric material in research laboratories due to its potential for rapid prototyping. However, PDMS is less desirable for mass production applications as it requires considerable processing time. With the development of micro/nano imprinting techniques, microfluidic structures can also be rapidly imprinted on other polymers such as Poly(methyl methacrylate) (PMMA) and polycarbonate using molding technologies. Even though PMMA is the material of preference for our application-a nanoporous membrane-based RNA extraction system-a PDMS membrane is an integral part for the functioning of pneumatically actuated valves and pumps. Since there is no well-established method that exists for bonding PDMS to PMMA, an attempt has been made in this thesis to increase the functionality of PMMA microfluidic parts. The work can be classified into two main categories: manufacturing of hot embossed plastic parts and development of bonding technology for PDMS and PMMA. To prepare the PMMA parts, a hot embossing template of brass is designed and manufactured for imprinting the microfluidic parts. Functional silanes such as Amino-Propyl-Tri-Ethoxy- Silane and Bis-Tri-Methoxy-Silyl-Propyl-Amine are used to obtain an irreversible chemical bond between PMMA and PDMS, which cannot be achieved effectively with existing bonding practices such as glow discharge and thin layer PDMS adhesive.