Bioptechs' Temperature Control Algorithm Explained

Bioptechs' Temperature Control System Algorithm

The five input values read by the controller are:

1. User set point
2. Dish temperature below 0.9°C below user setpoint
3. Dish temperature from 0.9°C below user setpoint to 0.1°C below setpoint
4. Dish temperature between user setpoint minus 0.1°C and user setpoint (control resolution)
5. Dish temperature at or above set point

There are six conditions that affect the output:

[a] Object temperature is below 0.9°C below user setpoint (cold startup mode). The heater output starts at 0 volts and increases at a fixed rate to a maximum value.
[b] Object temperature increases above 0.9°C below user setpoint and below setpoint -0.1°C. A latch is set for condition [f] and output voltage acceleration rate decreases from cold startup mode and the output voltage is set at a rate about five times the minimum decay rate.
[c] Object temperature is above user setpoint. The output voltage is reduced to one-third its previous value and decays at an accelerated rate until condition [d] or [e] occurs.
[d] Object temperature falls from above user setpoint to within control resolution band. The output voltage is held steady at the previous high state value, minus the accelerated decay value if present, at a minimum decay rate. (Accelerated decay value present only if preceded by condition [c].)
[e] Object temperature is within control resolution band. The output voltage is held steady but decays at a minimum rate.
[f] Object temperature or thermistor reading falls below 0.9°C below user setpoint. The output voltage is shut off to the object and an alarm sounds until the user cancels the alert by pressing the red button. This occurs if the temperature sensor is subject to cold shock. The amplitude, gain and decay rate, maximum current, operating current, response time, sensitivity, alarm range, and bandwidth are all variables that are adjusted specifically for each type of controller. Although each type of controller auto-ranges, its range of accommodation is limited to the typical thermal load of the object it is regulating. Each channel is controlled separately but both share the same setpoint.

Reference Information

Industry Standard Thickness for Coverslip Glass:

#00 = 0.060 - 0.080              #2 = 0.170 - 0.250
#0 = 0.080 - 0.120                #3 = 0.280 - 0.320
#1 = 0.130 - 0.170                #4 = 0.380 - 0.420
#1.5 = 0.160 - 0.190             #5 = 0.500 - 0.600

Microscope Stage Types:

Single plate stage is defined by a thick metal plate that uses a separate mechanical specimen translator to slide the specimen on the surface of the stage. Friction occurs between the specimen and surface of the stage. The specimen sometimes is placed into an adapter plate.

Triple plate stage is made of three individual plates; bearing mounted, to eliminate friction between the plates. The specimen is placed in or on the top plate and both the specimen and the top plate move together. This is a premium stage with the best X, Y, Z stability.

Motorized Stages are usually of the triple plate type and provide automation and superior repeatability.