Measure and Visualize Oxygen, pH or Carbon Dioxide Distributions in 2D for Biological Research

Software

All software versions, whether for O₂, pH or CO₂ imaging, have the same user interface, so you only have to get familiar with it once to be able to work with all.The software allows controlling the image recording process, and assists image processing and evaluation. An easy to use camera controlling user interface manages image acquisition and storage. Measure- ments which belong together can be organized in user defined sessions as separate folders and annotated with a free text comment. Acquired images can be single images or atomatically recorded time series.

Benefits:

• Display the sensor response in false color image
• Display the acutal pixel information
• Display ROI statistics of user defined polygon ROIs
• Interactive x- and y-axis profiles
• Z-axisprofiles for plotting ROI average at defined coordinates
• Follow kinetics through a time series and display as 2D-plots
• Side-by-side image comparison of selected images
• Alpha blending of false color sensor response with color image

The Smart Measurement Method

Fluorescence Ratiometric Imaging (FRIM) is a method for reading out the signal of a fluorescent chemical optical sensor. Ratiometric measuring compensates most of the common interferences, e. g. inhomogeneous lightfields. An optical sensor foil contains an analyte sensitive dye and a reference dye which are immobilized in a permeable polymer matrix layer. The indicator dye is emitting red or green fluorescence, depending on the analyte and respective  sensor foil type, which is dynamically quenched by the analyte while the reference dye is giving a constant green or red light signal respectively. These emissions meet exactly the red and green channel sensitivity of a color RGB chip.

Visualized Respiration in Leaves

Plants are both producers and consumers of oxygen, while CO₂ is constantly produced. Visualizing O₂ and CO₂ levels on the surface of plant leaves can give important information about oxygen demand and CO₂ production during light/dark conditions. The sensor foils attached to the leaf surface seal it against oxygen or CO₂ from ambient air and translate the respective analyte level with high spatial resolution. During a continuing dark phase the oxygen concentration on the surface of a rose petal , for example, decreases (see images left). The leaf consumes oxygen, while it produces a higher level of CO₂. With VisiSens it is even possible to investigate different petal structures and compare them in terms of oxygen consumption. Findings in these experiments might be important information relevant for transport and storage of cut flowers.

O₂, pH, and CO₂ Dynamics in the Rhizosphere of Crop Plants

Research on metabolic activity of plant roots and determining the best cultivation conditions for optimal growth will be of major importance for sustainable agriculture, as e. g. water supply and fertilizing could be adjusted for the respective crop plant. 2D imaging with VisiSens is performed to visualize O₂, pH, and CO₂ dynamics in complex root systems and the surrounding media. With this easy-to-handle but extremely precise device metabolic processes and how they change can be monitored over long time periods; parameters responsible for changes can be determined. The acquired analyte maps for distinct root regions are quantitative and have a resolution in sub-millimeter range.
Blossfeld et al., Quantitative imaging of rhizosphere pH and CO2 dynamics, Annals of Botany 2013, in press

Visualizing O₂, pH, and CO₂ in Sediments

Oxygen, pH, and CO₂ are key factors and indicators for microbial activity in sediments. Microbial degradation of organic material under aerobic conditions can be detected in an increased oxygen consumption. With VisiSens high resolution images can be recorded detecting analyte dynamics in different sediments or sediment depth over long time periods. The portable device can be applied in the laboratory as well as out in the field. As experiment conditions can be changed during measurements the impact of changing parameters on microbial activity can be analyzed.

Controlling Microbial Biodeterioration of Historical Monuments

Historical monuments are often subject to microbial biodeterioration. Effective treatments that inhibit biological growth on ancient rock surfaces have to be found. Oxygen imaging with VisiSens allows determining the health status of e. g. lichen after biocide treatment and with it assessing the effectiveness of the biocide. This technique also allows for a direct in situ analysis of the health state of a small quantity of biological material on the facade of historical monuments or buildings. Showing fast results it can be implemented in evaluation studies and conservation.
C. Ascaso & J. Wierzchos: Assessing Biocide Actions on Lichen with VisiSens, Oxygen in Action Competition Report, 2012