Heat Regulated Sample Chamber To Maintain Optimal Thermal Conditions For Biological Cell Microscopy

In order to acquire useful and accurate data from cells during biological cell microscopy, a temperature of 37° Celsius is required to maintain viability. To achieve a constant body temperature within a closed microscope slide, a feedback circuit is used as a thermostat. This circuit contains an operational amplifier that compares a constant voltage to the voltage from a thermistor and a transistor that activates a ceramic heating ring depending on the output voltage of the operational amplifier. The heating ring, which heats the slide to 37° Celsius, rests on the glass coverslip. A thermistor is used to monitor the temperature of the sample chamber. As the thermistor heats up, its resistance decreases, thus the voltage applied to the operational amplifier is increased. As the voltage from the thermistor rises above the constant voltage setpoint, it will cause the operational amplifier to decrease the current to the transistor, thereby turning off the heater. Here, a schematic of the circuit and verification of its effectiveness is presented.