Analytische Chemie
Filtern
Dokumenttyp
Sprache
- Englisch (2)
Schlagworte
- Fuel adulteration (2) (entfernen)
Organisationseinheit der BAM
The fluorescence properties of three molecular rotors, related to 4-dimethylamino-4-nitrostilbene (4-DNS), are studied versus different diesel/kerosene blends. In nonviscous solvents, these compounds can populate a twisted intramolecular charge transfer state which deactivates nonradiatively, successfully suppressing fluorescence emission. Solution experiments with diesel/kerosene blends showed a good linear correlation between the fluorescence intensity of the probe molecules and the diesel fraction of the blend. The dyes have been immobilized on paper, retaining their fluorescence behavior, i.e., negligible emission in the presence of nonviscous organic solvents and increasing fluorescence when the environment is increasingly viscous. When the impregnated paper is devised as a test strip, the latter is compatible with a newly designed smartphone reader system, which allows in-the-field measurements. The method can safely detect the presence of kerosene in diesel at ≥7%, which competes favorably with current standard methods for the detection of diesel adulteration.
Sensors are the scientific and technological extension of human senses and enormously expand human capabilities. Despite the fact that scientific and technological advances are usually seen in a positive light, the name of this conference, Sensors for Good, put me in a bit of a trouble, because in general science does not operate in ethical categories, but instead it just tells how far from the truth one is. In this respect, sensors help us in recognizing states and events beyond our immediate reach. Fortunately, sensors are used for many applications, such as environmental monitoring, food control, and alike, which unequivocally benefit society.
I will focus on a particular type of sensors, those that rely on microfluidics for operation and which are typically realized in lab-on-a-chip (LOC) devices. In this domain, where at least one of the dimensions through which a fluid flows is submillimetric, our natural senses fail, because the phenomena are too small to be detected either by eye, smell, touch, and even the common sense explanation that we learn for many years in school is not applicable, because the phenomena are dominated by different parameters. To give one simple example, in general the direction of flow in microfluidic channels does not depend on the up-down direction of the channel, because gravitational force or the weight of the fluid is negligible compared to the viscous forces present on the chip.
This presentation consists of three parts: initially, two sensors produced in our lab are presented, followed by a simulation oriented discussion on microfluidics and biosensors, and finally a project in progress that we are involved in is presented, concluding with a list of open issues raised during the presentation.