Focusing on perfect processes

With our wide ranging expertise in the development of optical measuring systems, our extensive experience in control engineering and our innovative solutions that utilize future oriented communications technology, we are the right partner to help optimize your metrology. As a one stop supplier of measurement and network technology, we have modern development tools and a pool of tested hardware and software modules at our disposal. Our customers benefit from our expertise and are able to efficiently develop solutions of the highest quality.

As an ISO certified company (ISO 9001 EN 13485), our innovative applications will ensure the maintenance of your quality standards.

What does DIALUNOX’s detector offer?

DIALUNOX’s novel micro fluorescence detector enables synchronous confocal fluorescence measurement, providing sensitivity that is equivalent to a top-of-the-range commercial spectrometer, all housed within a minuscule package. Our detector is suitable for implementation into in-line and on-line applications as well as in hand-held devices for final product evaluation.

DIALUNOX’s unique fluorescence detector was developed using an uncompromising approach to both optical performance and implementation, and can be used in a wide range of applications. The detector is available in single- or dual-channel formats (each having separate excitation and emission wavelengths). It uses confocal optics with small measurement windows for the assessment of liquids or solids. The detector is also packed into a solid casing that protects the device from dust and humidity and shields the sensor from electromagnetic radiation. Its lack of moving parts and low operating voltage (5V DC) make it suitable for use in hazardous environments without the need for extensive housing modifications. Whether analysis is required in a reaction vessel, in-line, in transfer, recycling, packaging or shipping, the ESE fluorescence detector can provide information to improve product quality and yield. This in turn helps decrease waste, and all without the need for complicated operational and calibration requirements.


What is fluorescence?

The fluorescence phenomenon has been observed for thousands of years and was mentioned in Chinese books as far back as 1500 BC.
Several hundred years ago, Johann W. von Goethe described fluorescent light phenomenon in his Theory of Colors. He asked his readers to: “… dip a fresh piece of horse chestnut bark into a glass of water; the bark will immediately turn sky-blue. “ However, only today do we truly understand this phenomenon and have the ability to control and make use of its processes.

Fluorescence is a special form of luminescence, an optical phenomenon in cold bodies, in which a molecule absorbs a high-energy photon, and reemits this light at a lower-energy or longer-wavelength. The term fluorescence is named after the mineral calcium fluoride, which has been seen to exhibit this phenomenon.

The energy difference between the absorbed and emitted photons is released as molecular vibrations (heat). Usually the absorbed photon is in the ultraviolet part of the spectrum, and the emitted light (luminescence) is in the visible range, but this depends on the absorption curve and Stokes Shift of the particular fluorophore. The Stokes shift, so named after the Irish physicist George G. Stokes, is the difference (usually in frequency units) between the spectral positions of the band maxima (or the band origin) of the absorption and luminescence arising from the same electronic transition.
Generally, the luminescence that occurs at longer wavelengths than the absorption is stronger than those at shorter wavelength. The latter may be called an anti-Stokes shift. Each fluorescent material has its own unique value, basically a fingerprint that allows the material to be clearly identified.

Where do we use fluorescence technologies?

Fluorescence has proven to be a versatile tool for myriads of applications. This powerful technique can be used to study molecular interactions in analytical chemistry, biochemistry, cell biology, physiology, nephrology, cardiology, photochemistry, and environmental science as well as in other areas. Fluorescence detection has three major advantages over other light-based investigation methods: high sensitivity, high speed, and safety. Safety here refers to the fact that samples are not affected or destroyed in the process and no hazardous byproducts are generated.

New developments in instrumentation, software, probes, and applications have resulted in a heightened popularity for a technique that was first observed over 150 years ago. There are many natural and synthetic compounds that exhibit fluorescence, and they have a number of different diagnostic, medical or biochemical applications.

For example, a fluorescent chemical substance or fluorophore can be attached to large biological molecule that is of interest and fluorescence can then be used to identify if the molecule of interest is present. This enables very specific analyses and, more importantly, quantitative results as the signal strength will depend on the number of fluorophores in the sample. Applications include DNA-sequencing, biochips, tumor and immunological marker detection.

Fluorescence is also used in many industrial applications, for example, to identify substances, surface coatings and final products. Applications include proof of authenticity (currency notes, expensive consumer products), inspection of coatings and tagging of fuel or oil. In addition, organic material when excited with UV-Light, will often display a strong auto-fluorescence and this attribute has a wide variety of applications without the need to use additional fluorescence markers. One such example would be the measurement of contamination (e.g. oil in water) and the detection of oil and fat residues on surfaces in hygiene testing.

How do you measure fluorescence?

Due to the fact that today‘s measurement technology is complex, expensive and only practical in labs, it has not always been possible to use fluorescence techniques for many applications. Lab-based measurement systems, while highly sensitive, are usually bulky and expensive.

The measurement of fluorescence demands complex, highly sensitive systems because the emission energy, the energy of the sample‘s fluorescence light, is nearly a million times smaller than the energy of the excitation. The fact that the emission has only a slightly different wavelength than the excitation (20-30 nm) is one of the challenges of this technique. In addition, lab-based measurement systems use a laser or high-pressure lamp (for variable wavelengths) to excite the sample and highly sensitive detectors, such as photomultipliers or ccd-detectors, to measure the emitted energy. The optical separation of excitation and emission is usually confducted at a measurement angle of 90°. This measurement principle is known as Off-Axis-Measurement and requires a very precise positioning of the excitation and emission beam on the sample. Therefore lab systems are very powerful and able to detect arbitrary fluorescent objects. However, these systems are very large, heavy, consume high amounts of energy and cannot be used under difficult environmental conditions due to the fact that temperature-differences, humidity or dirt particles have an enormous effect on the measured results. The operation of these systems normally requires trained personnel, which incurs additional costs. Thus the use of these systems is still limited to labs and research institutions.

What is special about DIALUNOX’s fluorescence detectors?

DIALUNOX has developed a small, easy to use fluorescence measurement system, which is extremely sensitive, robust and affordable! With our consistent use of modern microsystems technology, state of the art LED- and filter technology, as well as highly integrated embedded systems, we were able to develop a fluorescence detector that can be used for mobile measurement systems or integrated into systems for online process monitoring (e.g. in production lines or labs).

The fluorescence detector‘s distinguishing features are its size, ease of use and outstanding price to performance ratio. In addition, the sensitivity of the detector is comparable with expensive lab systems.
DIALUNOX’s ESElog and Fluo Sens measurement systems work with impinging light based on a confocal measurement principle. In contrast to the off-axis principle, the excitation and emission beam in confocal systems have the same, parallel course. In the detector, the measurement signal is extracted by a precise system of beam splitters and filters. This can be used on arbitrary surfaces as well as in liquids.

One of the major advantages of the confocal principle compared with the off-axis principle used by lab-based systems is the much higher flexibility regarding detector and sample positioning. As seen in the comparison graph below, the accurate positioning of the sample is highly critical when using the off-axis principle whereas with the confocal principle positioning of the sample is not critical and comparable results can be easily obtained.