An apparatus for use in controlling the temperature of one or more substances passing through one or more microfluidics channels in an analysis device is set forth. The apparatus includes a heating unit having first and second surfaces. The first surface of the heating unit is constructed so that it is at least partially exposed for cooling of the heating unit. The apparatus also includes a thermally conductive medium that is disposed proximate the second surface of the heating unit. The one or more microfluidics channels are disposed in the thermally conductive medium. In one embodiment, the one or more microfluidics channels are in the form of a plurality of capillary columns, such as those used in instruments for capillary electrophoresis. Each capillary column is substantially surrounded by the material forming the thermally conductive medium. In another embodiment, the thermally conductive medium, along with the corresponding plurality of capillary columns, can be easily disengaged from the heating unit in a non-destructive manner thereby allowing the heating unit to be reused.