Employing fluorescence analysis for real-time determination of the volume displacement of a pneumatically driven diaphragm micropump

Abstract

In this work, we propose a new optical measurement method and setup to investigate the dynamic behavior of a pneumatically driven diaphragm micropump in a microfluidic system. The presented method allows a contact-free spatially and temporally resolved determination of the membrane displacement. Hence, it enables to derive the volume flow rate, generated by the micropump. The method is based on the Lambert–Beer law, which describes the intensity weakening of light traveling through a medium with an absorbing substance. The fluorescence emission of a medium can thus be related to the light traveling length. The measurement method is used to deduce the flow rate profile generated by the micropump of the Lab-on-Chip system Vivalytic from Bosch Healthcare Solutions. We further quantify effects of fluidic components and system parameters on the transient flow rates. This allows the determination of maximum flow rates and pumping cycle durations as a basis for the implementation of fluidic processes on the system. The presented method requires neither additional, integrated sensor components nor a complex measurement setup. It can be implemented in any microfluidic system with membrane-based, optically accessible micropumps without major hardware modifications.