Creating Programs
Tech Support: 1-800-4BIORAD • 1-800-424-6723 • www.bio-rad.com
5-9
Considerations During Program Creation
Once you have written the body of your raw program, there are decisions to make
before creating your Tetrad 2 program. They concern how your steps should be
implemented. These decisions involve the following:
•
Temperature control mode
•
Lid control mode
•
Temperature ramping rate (advanced mode only)
•
Temperature hold time
•
Temperature time extend (advanced mode only)
•
Temperature increment (advanced mode only)
•
Temperature gradient (available with the 96-well Alpha unit only)
•
Outside of the example protocol: other considerations
Choosing a Temperature Control Mode
The DNA Engine Tetrad 2 cycler can control incubation temperature in two possible
ways, each of which has different implications for the speed and accuracy of sample
heating. These include
Calculated Control
and
Block Control
.
Calculated Control
When using calculated control, the DNA Engine Tetrad 2 cycler estimates sample tem-
peratures based on the block’s thermal profile, the rate of heat transfer through the
sample tube or slide, and the sample volume or mass. Since this estimate is based on
known quantities and the laws of thermodynamics, sample temperatures are controlled
much more accurately than with block control.
Since the sample temperature will always lag behind the block temperature, the
DNA Engine Tetrad 2 cycler can adjust the block temperature to bring samples of a
specific volume in a specific vessel type to programmed temperatures. This is done
through optimized overshoots of the block temperature by a few degrees for a few
seconds, which bring samples to the desired temperature more quickly.
