Advanced Assay Stability

Steady experimental conditions are a prerequisite for robust and high-quality data. Temperature is one factor that may significantly affect experimental results, especially when screening assays in 384 or 1536 well formats. If temperature fluctuates when an assay or detection is in progress, changes in thermodynamic conditions can influence many events including molecular interactions, the efficiency and kinetics of chemical and biochemical reactions and the photon yield of luminescence and AlphaScreen®/AlphaLISA® assays. This can result in irreproducible results, potential false positive signals and poor statistical outcomes. 

Many factors can influence the internal operating temperature of a microplate reader. In a lab, room temperature can fluctuate depending on location, exposure to sunlight, time of day, local climate, season, heat from neighbouring lab instrumentation and use of heating or air conditioning. 

Fig. 1: Temperature fluctuations in a laboratory over a 12-hour span. The room temperature increases up to 3°C when the lab is busy and different instruments are operated.

In general, microplate readers can control the internal temperature from a few degrees above room temperature to 45°C or higher. Typically, these instruments work to regulate the measurement chamber temperature. The gap between room temperature and the controllable temperature is mainly due to electronics within the instrument that generate heat, especially if the reader is heavily used. 

A stable detection environment – even below room temperature

The new Advanced Assay Stability (AAS) system enables the PHERAstar® FSX to match room temperature conditions and to be maintained at any temperature between 18 and 45°C. It achieves this by automatically heating or cooling the microplate measurement chamber depending on the external environment.

Fig. 2: PHERAstar FSX with AAS system

The AAS system provides a steady temperature that is unaffected by external environmental changes while the plate reader is operating - providing improved assay stability and more reliable data. 

The special design of the AAS system, which is a closed system, also eliminates the external airflow to the inside of the plate reader and helps keep humidity constant.


Benefits of the PHERAstar FSX with AAS system

  • Plates that are incubated at room temperature remain at the same temperature when entering the reader and during measurement
  • Stable temperature inside the reader regardless of external or internal temperature fluctuations
  • Reproducible screening results across laboratories in different locations and environments worldwide 
  • Consistent environment for temperature-sensitive applications and kinetic measurements
  • All plates in a batch or a screening campaign are measured under the same conditions
  • Ideal conditions for assays that need to be run at room temperature or below
  • Significant reduction of reader cool-down time when switching from one application to another (e.g., from incubation at 37°C to room temperature at 23°C)
  • Constant humidity and reduced airflow reduce sample evaporation compared to a conventional plate reader.

An empirical analysis of the benefits of the PHERAstar FSX with AAS system as well as comparisons to competitor readers can be found in the application note Advanced Assay Stability system facilitates a stable detection environment for temperature-sensitive assays

The AAS system is only available on the PHERAstar FSX microplate reader. It adds about 10 cm additional depth at the rear of the instrument. The overall size of the plate reader with AAS is slightly larger than the standard PHERAstar FSX (see specifications). No additional installations, tubes or devices are required for operation.

Fig. 3: The AAS system adds about 10 cm additional depth at the rear of the PHERAstar FSX. No additional tubes or devices are required.


The plate carrier has the same plate in/out positions, and the reader feet are in the same position on every PHERAstar FSX to enable seamless automation and uniform compatibility with the BMG LABTECH Stacker.

Newsletter Sign-up