Temperature control for microscopy imaging : incubation chambers
Tracking biological processes using microscopy imaging requires maintaining the cells as healthy as possible and sometimes for very long period for time depending on the experiments. Several temperature controllers are available; they all have positive and negative features, it lends on microscope users to evaluate which one is best suited for their experiments. Incubator chamber for microscope is a stable way to control the cells temperature and environment.
Introduction
Microscope thermal stages can thermalize across a large range of temperatures, from -190°C to more than 500°C depending on the application. This is why they are the system of choice for applications where very high freezing/heating rates are required. However, simpler thermal stages exist for live cell imaging purposes in biological research, with temperature ranges between -5° C and 99°.
How does an incubation chamber for microscopes work?
Incubator boxes are generally made of polycarbonate (plexiglass) and enclose most of the microscope. Temperature control is achieved by an electrical resistance and/or by regulating the temperature of the gas that flows in the chamber. Incubation boxes are able to thermalize the whole microscope after a sufficient time, tipically a 3 to 4 hours period of time to reach a good equilibrium at the microscope level. This system is particularly suitable for long-term imaging as it maintains the temperature of the microscope to ensure a steady focus level during acquisition.
Features
Homogeneous sample temperature
Because most of the microscope is thermalized inside the incubator box, temperature is very stable over the time. Stable temperature prevents focus drift.
No requirement of objective heating system
Incubation boxes do not require to be coupled to an objective heating system to prevent phenomena associated with heat sink from the immersion objective. Objectives are enclosed in the box at the same temperature so they don’t generate thermal gradients across the sample. Nevertheless, objectives should withstand the thermal expansion generated in the temperature range of the incubation box.
Long time-lapse acquisition
Incubation chambers control the whole cell environment including other parameters together with temperature, thus they are well-suited for mammalian cell imaging and long term experiments. Temperature and steady focus are maintained for long periods of time. Flexibility for different specimens Fully compatible with microscope slides as well as different sizes of Petri dishes and multiwell plates.
Easy to use
Once the box is set-up, it is easy to use, and doesn’t require any particular training from the operators.
Drawbacks
Slow temperature shifts (30-60 min)
The main advantage of these systems, their stability, can become a drawback when temperature shifts are needed. Indeed, temperature changes are rather slow given the system’s inertia. Thus these systems are not suitable to investigate biological phenomena that need fast temperature changes.
Limited temperature range
Most of the commercially available systems scan thermalize between RT +3°C to 50°C, although temperatures below ambient are achievable through air conditioning systems. However, when using incubation boxes provided of air conditioning, strong local temperature increases can occur across the sample when turning on DIC illumination or during extended acquisitions using strong light sources.
Ergonomy
These systems are custom-installed on specific set-ups and cannot be moved from scopes to scopes.
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