| Description |
Significant progress has been made in recent years advancing microfluidic extraction systems for nucleic acids (NAs). However, much remains to be done in the area of sample preparation as it presents significant challenges and additional steps before nucleic acids can be extracted. These difficulties prompted the design of a versatile, disposable extraction system that was robust enough to handle a wide range of raw biological samples and perform the necessary sample preparation protocols. This design was accomplished through an iterative design process, building on Johnsons's polydimethylsiloxane (PDMS) extraction chip [1]. With a primary focus on reducing cost and improving manufacturing time, a new chip was designed and constructed from 3 layers of laminated polycarbonate and a silicone flexible membrane layer. Four features were adapted or redesigned to make the chip fully function: the microvalves, fluid inlet connections, reservoir-pumps and microfilter. Significant design changes were used to make this integration possible. The most notable change involved removing the lower portion of Johnson's PDMS chip[1] and integrating it as a permanent fixture on the pneumatic actuation system. This modification greatly simplified the chip, minimizing cost and manufacturing time while allowing the microvalves and reservoir-pumps to function exactly as before. In addition to designing a new extraction chip, the supporting pneumatic actuation system was redesigned and rebuilt as well. Pneumatic failures in Johnson's pneumatic machine were common, which were caused by an excessive amount of flexible tubing and connectors. To create a more reliable pneumatic machine, a central manifold was constructed with access to the necessary pressure sources. The new system was tested with water for basic fluidic functionality. It successfully demonstrated working valves, reservoir pumps and filter flow. Subsequent testing revealed the successful extraction of DNA from a purified sample. The new extraction system is simpler, easier to use and fabricated in 1/16th of the time and produced for 1/60th of the cost of Johnson's PDMS chip. |
