We offer a 24-channel reader SDR (SensorDish Reader) for measurement of pH and oxygen concentration in 24-well microtiter plates (SensorDishes®). These sterile multidishes contain optical sensors for oxygen (OxoDish®) or pH (HydroDish®), which are located at the bottom of each well. The sensors are fluorescent, analyte-sensitive dyes embedded in a tissue-compatible polymer. The SensorDish® is placed on top of the SDR device and read out from the bottom. The SDR offers completely new possibilities for on-line monitoring of cell cultivation and assay improvement. Toxicological tests are another possible application.

The principle of the sensor operation is based on luminescence lifetime detection as analyte-dependent parameter. Therefore, the signal is not affected by fluctuations in the light source intensity or the detector stability. Intensity fluctuations caused by changes of the optical properties of the sample (coloration, turbidity, intrinsic fluorescence, refractive index etc.) do not interfere with the measurement. Measurements do not have to be performed under total exclusion of light but can take place under dim, ambient light. For measurements in bright places, we offer a light-tight cover for the SensorDishes. Excitation of the analyte-sensitive dyes and collection of their fluorescence emission takes place through the bottom of the SensorDish® by the SDR device attached under it. This non-invasive method enables rapid online screening without addition of reagents or need of sampling. The whole system is controlled by a PC for online control as well as data storage.

The plate is a sterile, polystyrene microtiter plate in the common 96-well format with 96 integrated optical sensors. A sensor is immobilized on the bottom of each well. This sensor can be read out from the bottom side like depicted beneath. This can be done bye almost any commercially available fluorescence plate readers. High accuracy is assured by using two different dyes to get an internally referenced signal.