Heating The Mouse - SA Instruments 1030 Operation Manual

Air Heater System
On/off control with manual control of the heater duty factor should be selected
when using the SAII Air Heater System. Here, heater duty factor, PWM max heat and
Maximum Heat Output all refer to the same setting.
When the mouse temperature is several degrees below the desired set point, the duty
factor should be set near 100%. As the mouse temperature gets closer to the set point,
reduce the duty factor (to near 50%) to prevent temperature overshoot. Once the
measured temperature has reached the set point the system will turn on and off as
required to hold the temperature at the set point.
Light used to control the heater is pulse width modulated (PWM). Selecting a small duty
factor results in narrow light pulses which turns the heating element on for short time
durations. A large PWM value results in wide light pulses and increased heat from the
Heater Module.
Manual operation with manual control of the duty factor allows the Air Heater
System to operate without regard for the measured temperature or the value of the set
point. This method can be used to heat the local environment in the magnet bore
before positioning the animal.

Heating the mouse

In the main HEATER window, select the temperature probe and set the set point.
Position the tube from the Heater Module a few inches from the mouse. It may be
necessary to insulate the environment around the animal from the magnet bore. Chilled
water for gradient coil cooling may dramatically reduce the temperature of the bore. A
plastic tube section, a plastic sandwich bag or foam can be used to funnel air from the
heater around the animal. When using a plastic sandwich or larger bag, open both
ends of the bag to allow air flow both into and out of the bag.
Turn the Air Heater System on. Observe that the green power indicator is illuminated
on the Heater Module. Also observe that the yellow heat indicator is intermittently
flashing. If the heat indicator is not flashing check that the temperature measurement is
lower than the set point (refer to Appendix C). Note that the control signal for the
Heater Module will not be on if the temperature probe is not connected.
Set the duty factor based on the measured temperature of the mouse. If the mouse's
temperature is more than 5 °C below the set point, use a duty factor of 100%. Observe
the measured temperature of the mouse and decrease the duty factor to minimize
overshoot. When the measured temperature reaches the set point, a duty factor of 50%
or more should maintain the temperature within +/-0.1 °C.
Caution: The temperature at the end of the heater hose
The rectal probe can be used to check Air Heater System performance. Place the
probe just inside the 2m warm air tube and set the set point high to 70
factor to 100%. The measured temperature on the monitor display should rapidly climb
o
to 55 C or more.
6-4
can be 55 °C or more. Do not position the
hose closer than 4" to the mouse.
adequate air flow around the mouse.
Revision C, August 2013
Allow
o
C and the duty