A compact, low cost, automated
electrophoresis apparatus provides for the optical detection of multiple
DNA samples. A substantially cylindrical gel
cartridge houses multiple sample lanes that are sealed on the outer periphery by a shrink tube, which allows for straightforward
gel casting, as well as for the pre-
casting of sequencing gels. The radial
column design of the gel
cartridge also facilitates the use of a
light source to illuminate one or more sample lanes at the same time. The radial
column design further provides for an increased sample lane depth that allows for reading through a greater
optical path length of the migrated samples, yielding greater optical
signal strength, and an increased
signal to
noise ratio. The gel lanes can be designed to vary in depth as a function of longitudinal length, allowing for a variable
current density. Additionally, this radial design allows for different types of optical detection techniques to be performed on the sample, including
transmittance and
fluorescence. A
system of cooling channels incorporated into the radial
column design allows for a
coolant to be recirculated in the cooling channels between the actual running sample lanes for better lane-to-lane
thermal control. This cooling
system allows higher operating voltages and facilitates the use of multiple thermal zones, as required, for instance, for single-strand conformation polymorphism (SSCP) applications.