Markus Gläser’s scientific contributions

Besides traditional machining processes, unconventional machining by EDM (Electrical Discharge Machining) is used, especially when precise cavities with complicated shapes are required or hard to machine alloys need to be machined. For the production of a geometrically complicated workpiece, numerous differently shaped electrodes are required due to the variety of the single cavities and the tool wear. Due to the process-related tool wear, the electrodes can only be reused a few times. Thus, process chains consisting of milling electrode production, automated electrode changing and CNC-controlled erosion process are frequently used. After fabrication of the milling electrode, the electrode geometry is measured for quality control usually using a tactile measuring device. In order to assist in the orientation of the electrode in the EDM system, the consideration of measurement results with respect to a reference point would be helpful. However, the transfer of the measured coordinate parameters from the measurement system to the EDM system is not possible in most cases since there is no connection between the measurement system and the EDM system. In addition, the tactile electrode measurement is time consuming. With the help of a machine-integrated optical measuring system, it will be possible to save time for measuring the electrodes by automated optical measurements and thus replacing the tactile measuring method. The present study describes the technological development of a machine-integrated optical measuring system, which enables a qualitative optimization of the process chain from the production of the EDM electrode and the subsequent erosion process. The design of an optical measuring system consisting of CCD (Charge Coupled Device) sensors and a custom software for the evaluation of the results of the optical measurements are presented. The presented solution will prospectively be implemented into an industrial EDM-machine with the aim to achieve a more efficient process chain and to avoid incorrect machining.

Wastewater treatment plants are the main release sources of pharmaceutical compounds present in surface waters. Even at low concentrations, many of these substances have long-term adverse effects on the environment. For an efficient control of pharmaceutical removal, a real-time recognition is a prerequisite. Currently, quantification of such compounds is done in special equipped laboratories and is rather time-consuming and expensive. Here, we introduce a novel biosensor for the detection of the pharmaceutical compound diclofenac, which can be produced with low costs, is easy in handling and can be applied directly on-site. Recognition of diclofenac is based on genetically engineered yeast cells which produce green fluorescent protein in a diclofenac concentration-dependent manner. Centerpiece of the sensor is a foil-based microfluidic flow cell, which allows supply with nutrient solution and analyte while preventing loss of reporter cells. Readout of data is accomplished by a newly developed spectrometric detection unit. With this device, we are able to determine diclofenac concentrations in a range from 10 to 50 μM.

Ziel des Vorhabens HIGS "Hochintegrierte Ganzzellsensoren für die Umwelt-und Medizintechnik" war die Entwicklung einer neuartigen Generation von Ganzzellsensoren, welche durch die Reaktion lebender Zellen die Bewertung der biologischen Wirkung von biomolekularen oder nichtbiologischen Analyten ermöglichen. Die innovative Lösung soll es weiterhin erlauben, dass zukünftig solche Sensoren, bei denen gentechnisch modifizierte Mikroorganismen zum Einsatz kommen, durch Integration in ein modulares Mikrofluidiksystem auch beim Arbeiten in konventioneller Arbeitsumgebung sowie in offenen technischen Systemen den Sicherheitsstandard S1 erfüllen. Dieses soll durch zwei in das Mikrofluidiksystem integrierte Module für die Detektion von einzelnen möglicherweise freien Zellen und deren sichere Denaturierung sichergestellt werden. Zusätzlich soll die Entwicklung erstmalig durch neuartige Konzepte zur internen Referenzierung mittels elektrischer Messung und zur biologisch-chemischen bzw. physikalischen Regenerierung der Sensoroberfläche applikationsreif erweitert werden. Wichtige Teilkomponenten des Systems umfassen die Mikrofluidikzelle, die Fluoreszenz, Impedanz-und Denaturierungsmodule sowie die gentechnisch modifizierten Sensor-Hefezellen. Erste Anwendungen des Prototypen werden im Bereich der Wasseranalytik am Bespiel der Detektion des Schmerzmittels Diclofenac präsentiert.

First results of the spectral 2D analysis of biological, fluorescent samples using a new video spectrometer (AOS) are presented (see Fig. 1). An acousto-optical TeO2-crystal can be tuned by ultrasound to act as a narrow, spectral filter for incoming light [1]. The wavelength ranges from 250-800 nm with a spectral resolution higher than 2.5 nm thus representing an ideal tool for in vitro analysis of fluorescent processes in biological systems. In combination with a microscope and a camera, processes can be resolved spatially (200 x 200 px) and in time (> 40 ms). Here, we exemplarily monitor genetically modified yeast cells containing fluorescent proteins such as tRFP or eGFP in a microfluidic device. These proteins are excited by an appropriate light source, e.g., an LED, and emitted fluorescence will finally be detected by adjusting the AOS to the excitation peak. The system offers the possibility to examine cellular reactions in response to changes in the surrounding medium and to monitor different, fluorescent processes with multiple dyes simultaneously simply by tuning the crystal. Applications are conceivable in genetic engineering, biotechnology, medical as well as life sciences.