How does the Soleris system read the vials?

The vial features an agar plug, located at the bottom of the vial, through which optical measurements are performed. Above the plug, liquid growth media and appropriate dye(s) are present. The sample is added to the liquid broth. The agar plug area is not influenced by the particulates in the sample, since only small molecules and ions can diffuse to or equilibrate with the plug. This creates a clear window that allows precise optical measurements of changes in colour due to microbial growth. 

These changes are detected photometrically by an optical sensor. Light from light-emitting diodes pass though the agar and a photodiode on the other side of the vial reads the colour change as microbial growth occurs. As soon as a colour change is detected, the time of detection is recorded. The instrument measures the optical properties of the window every six minutes. 

This automatic detection makes Soleris a valuable tool for real-time detection of a wide range of microorganisms in various products. A crucial element to the technology is the monitoring of these changes in the agar zone or the well, which is separated from the liquid medium. This eliminates the masking of the optical pathway by the product, or microbial turbidity. 

Changes in colour, expressed as optical units, are monitored by the optical sensor and recorded in the computer.