Heater tubes annular flow

The PCR channel for these CFPCR devices can also consist of either capillary tubes [99, 100] or an on-chip annular channel [95, 101]. The serpentine channel formats on a monolithic chip can utilize thermal insulation with the aid of air gaps [102, 103] or by utilizing glass chips with a low thermal conductivity [104, 105]. Recently, a novel spiral chaimel configuration was also used to perform CFPCR on a single PC wafer with a circular arrangement of three temperature zones, allowing for a compact footprint and a minimal number of heaters for temperature control [106, 107]. CFPCR microfluidics can also use a uiudirectional PCR or oscillatory flow [108]. 

The first loop circulates Freon-12 through a pump, reservoir, heating coil, test section, condenser, and back to the pump. The second loop circulates hot water, which is pumped from the heater to the annular space between the Freon and hot water tube. In the test section the Freon and hot water flow counter-currently. 

---