An inexpensive and portable microchip-based platform for integrated RT–PCR and capillary electrophoresis

Abstract

We present an inexpensive, portable and integrated microfluidic instrument that is optimized to perform genetic amplification and analysis on a single sample. Biochemical reactions and analytical separations for genetic analysis are performed within tri-layered glass-PDMS microchips. The microchip itself consists of integrated pneumatically-actuated valves and pumps for fluid handling, a thin-film resistive element that acts simultaneously as a heater and a temperature sensor, and channels for capillary electrophoresis (CE). The platform is comprised of high voltage circuitry, an optical assembly consisting of a laser diode and a charged coupled device (CCD) camera, circuitry for thermal control, and mini-pumps to generate vacuum/pressure to operate the on-chip diaphragm-based pumps and valves. Using this microchip and instrument, we demonstrate an integration of reverse transcription (RT), polymerase chain reaction (PCR), and capillary electrophoresis (CE). The novelty of this system lies in the cost-effective integration of microfluidics, optics, and electronics to realize a fully portable and inexpensive system (on the order of $1000 in component costs) for performing both genetic amplification and analysis - the basis of many medical diagnostics. We believe that this combination of portability, cost-effectiveness and performance will enable more accessible healthcare.

Fast identification of foodborne pathogenic viruses using continuous-flow reverse transcription-PCR with fluorescence detection

“…Quake and co-workers (Marcus et al 2006b) were one of the first groups to demonstrate microchip RT-PCR in a single chamber. Although there have been a few demonstrations Hsieh et al 2009;Huang et al 2006;Kaigala et al 2008;Lee et al 2008;Lien et al 2007;Lien et al 2009;Marcus et al 2006a, b;VanDijken et al 2007) of chamber stationary RT-PCR microfluidics, they generally lack the flexibility to change the reaction rate, resulting in more cycling and heating time. Moreover, in order to reduce the reaction time and power consumption, the system thermal mass often needs to be optimized considerably (Liu et al 2002).…”

Lab-on-a-chip: a component view

“…By applying a voltage across two electrodes placed at the end of the channels, sample is injected into the separation channel and isolation of particles occurs. Ease of implementation, portability, minimal reagent consumption and high speed have made CE Kaigala et al 2008;Vieillard et al 2007) by far the most popular and matured technique in separation technology. Separation efficiency in CE is often limited by dispersion and this is investigated in (Ghosal 2006).…”

Optothermal sample preconcentration and manipulation with temperature gradient focusing

“…Available methods that can provide the required temperature variations include thin-film heating elements made of platinum (Pt), indium tin oxide (ITO), and non-metallic polysilicon Kaigala et al 2008;Liao et al 2005); heating/cooling blocks (Ross and Locascio 2002;Balss et al 2004;Sommer et al 2007); embedded resistive wires or silver-filled epoxy Vigolo et al 2010); external Peltier modules (Ross and Locascio 2002;Huber and Santiago 2007;Liu et al 2002); localized convective heating (Lee et al 2004, Wang et al 2003; infrared, visible, or microwave radiation (Duhr and Braun 2006;Krishnan et al 2009;Oda et al 1998;Ke et al 2004;Issadore et al 2009); chemical reactions (Guijt et al 2003); and Joule heating (Sommer et al 2007;Erickson et al 2003). Among the abovementioned methods, heating/cooling blocks (Ross and Locascio 2002;Balss et al 2004;Sommer et al 2007), Peltier elements (Huber and Santiago 2007;Matsui et al 2007), and Joule heating in a variable cross-section microchannel (Ross and Locascio 2002;Sommer et al 2007) have been used for analyte preconcentration with TGF.…”