In this paper we present the design, realization and measurement results of a novel optical flow cytometric system for static and dynamic absorbance-based biochemical analysis fabricated by Si-micromachining. This lab-on-a-chip platform comprises integrated polymer based waveguides and a single biconcave air/resist lens for incident light guiding and focusing to increase the measurement sensitivity and minimize coupling losses. The microfluidic channel structure enables versatile 3D hydrodynamic sample focusing to an arbitrary position in the channel. For the optofluidic interconnection a new plastics holder was fabricated to simplify chip and sample handling. To confirm the fluid dynamics and raytracing simulations and characterize the sensor we conducted static and dynamic absorbance and extinction measurements stating the high sensitivity and applicability of this analysis system.