Entwicklung einer in den Probenröhrchen Sortierer ATRAS integrierten Füllstandsmessung für Blut- und Urinprobenröhrchen

Abstract

Das Ziel dieser Arbeit ist es, eine Füllstandsmessung für Blut- und Urinprobenröhrchen zu entwickeln, die in das Sortiergerät ATRAS eingebaut werden kann. Auf diesem Weg sollen Proben, die zu wenig Inhalt für die anschließenden Analysen enthalten, erkannt und in ein Fehlerfach sortiert werden, damit für die Untersuchung keine Ressourcen unnötig verbraucht werden.

The present Bachelor thesis deals with the topic of developing a measurement in order to state the fill level of blood- and urine-sample tubes. The aim is to find out those samples, which do not have enough liquid for carrying out the following analysis, and would consequently lead to a wasting of resources. This method is to be integrated into the ATRAS (Automatic Tube Registration And Sorting), an instrument which isolates, recognizes and sorts tubes, depending on which analysis is to be done with the interior. Therefore the development must be adjusted to the given circumstances in the mainframe. The first part of the development is devoted to the problem of identifying the tubes while transporting them on a conveyor belt, like it is done in the ATRAS. The solution was achieved by using a scanner and a self-invented program, which records the profile of the passing object. Because of this information conclusions could be drawn to the volume the tube possesses. Furthermore, investigations were done whether the signal should be transmitted better by current or voltage in order to optimize the identification. As a result the transmission by current showed smaller interferences. In the second part, the concentration lay on the actual measurement of the fill level. Even though in this context many different procedures exist, the only acceptable one in this case was the method determining the weight. For this purpose two series of tests were carried out, one with resistance strain gauges, the other with a piezoelectric sensor. However, the first mentioned method did not have the required sensitivity to distinguish between the varying states of fill. In contrast, the piezoelectric sensor fulfilled the demands, thus further investigations were established to find out the best way the sensor could be applied. The given results underlined the manufacturer’s information, which is to use it in an upright orientation. Finally, both pieces of development were combined by integrating them into one program, which includes the identification, the measurement of the weight and the respective evaluation. The final result is a measurement, which has the ability to find out samples with more than ten percent fault of the real filling level.