Microchannel Electrophoretic Separations of DNA in Injection-Molded Plastic Substrates

Abstract

Microfabricated electrophoretic separation devices have been produced by an injection-molding process. The strategy for producing the devices involved solution-phase etching of a master template on a silicon wafer, followed by electroforming more durable injection-molding masters in nickel from the silicon master. One of the nickel electroforms was then used to prepare an injection mold insert, from which microchannel chips in an acrylic substrate were mass-produced. The microchannel devices were used to demonstrate high-resolution separations of double-stranded DNA fragments with total run times of less than 3 min. Run-to-run and chip-to-chip reproducibility was good, with relative standard deviation values below 1% for the run-to-run data and in the range of 2-3% for the chip-to-chip comparisons. Such devices could lead to the production of low-cost, single-use electrophoretic chips suitable for a variety of separation applications, including DNA sizing, DNA sequencing, random primary library screening, and rapid immunoassay testing.

Peer Reviewed: Polymeric Microelectromechanical Systems.

“…The large EOF for glass devices requires either a dynamic or polymer overcoat on the wall to suppress the EOF with DNA. Indeed, both single-and double-stranded DNA separations have been carried out on unmodified plastic microfluidic devices (12,22,24,25).…”

Modification of a poly(methyl methacrylate) injection-molded microchip and its use for high performance analysis of DNA

“…The pressure was removed at room temperature after 30 minutes. Compared to the thermal bonding methods reported [11,20], the method has a number of advantages such as a simplicity of process, straightforward conditions, etc. Most importantly, the method does not change the microchannel profile or block the microchannel because the solvents are volatile.…”

“…A number of polymeric materials have been used to create microfluidic devices, such as poly(methyl methacrylate) (PMMA) [4], polycarbonate [5], SU-8 photoresist [6], Zeonor 1020 [7], and the elastic poly(dimethylsiloxane) (PDMS) [8,9]. Polymeric substrates have been patterned using laser ablation [3], X-ray lithography [10], injection molding [11], and imprinting from master templates [12].…”

“…Mass production may effectively reduce the cost of polymeric devices. There are many mass production methods for polymeric devices, such as a casting protocol for silicone devices [13], production of microseparation channels in plastic substrates via laser ablation [14], use of a nickel electroform to prepare an injection-mold insert for producing microchannel chips from an acrylic substrate [11], and rapid prototyping for injection-molded integrated microfluidic devices and diffractive element arrays [15]. In summary, injection molding, compression molding, or stamping processes provide the possibility of producing hundreds of thousands of essentially uniformly fabricated plastic separation microdevices from a single master in a cost-effective manner.…”

Surface modification in microchip electrophoresis

“…There are, however, some manufacturing issues associated with glass microchips, which makes the use of alternative materials like different polymers attractive [28]. An advantage of polymer-based microfluidic chips is the wide choice in microfabrication techniques like injection molding [29], laser ablation [30], imprinting [31], or hot embossing [32]. For such microfluidic devices inexpensive mass production is possible which makes them attractive as disposable devices for commercial applications.…”