Contact free dispensing for in vitro diagnostics : challenges of the reagent diversity on the performance of appropriate dispensing technologies Zusammenfassung: Trends in the laboratory diagnostic are mainly triggered by the improvement of the medical values of the offered test parameters and the increase of the test efficiency. Improving the test efficiency and the accompanying economic added value for the healthcare system aims to reduce the costs per result. Two mayor cost factors for the IVD tests are the consumption of reagents and disposables. Hence the trend of the industry is towards the reduction of the needed reagent volumes in future IVD analyzers which could be achieved by better detection methods and innovative dispensing systems. A most promising method to handle reagent volumes down to the sub µl range is the usage of microfluidic contact free dispensing systems. In this account it has to be ensured that the dispensing system ejects the whole spectrum of IVD reagents precisely and accurately. Aims of this work are the description of the whole IVD reagent spectrum according their fluidic properties; the evaluation of selected dispensing systems regarding their applicability as IVD reagent dispenser; and the definition of operational modes to ensure a lossless fluid transfer from the dispensing nozzle into the reaction vessel. The required energy for a contact free fluid breakup form the dispensing nozzle is mainly determined by the fluid properties density viscosity and surface tension. Hence in order to ensure a reliable fluid breakup for all IVD reagents these fluid properties have to be known. These are not disclosed in the scientific literature thus far; hence their determination is one key element of this work. To achieve this objective a representative set of 646 IVD reagents are selected measured and arranged in a diagram: the fluid properties landscape. Out of this landscape eight simple and easy to prepare model fluids are developed covering almost the whole property range of the IVD reagents (offered by the Roche Diagnostics GmbH). They are aimed to evaluate dispensing systems for their applicability of dispensing the IVD reagents within the desired performance. It is demonstrated in this work that the model fluids behave like real IVD reagents when the aforementioned fluid properties are almost identical. The differences in their chemical compositions do not influence the dispensing result significantly so that instead of an evaluation with all IVD reagents only an evaluation with these eight model fluids is sufficient.The required volume range of present and fut ...