Abstract: The present invention relates a laboratorial microsystem for biological fluid analysis, especially the concentration measurement of biomolecules in those fluids, for application in clinical analyses. This device combines in a single microsystem the microchannels, the optical filters, the detectors and the readout electronics, enabling the measurement of the concentration of several biomolecules using white light source as illumination, thus avoiding the use of a wavelength dependent light source (such as a laser, for example). Its operation is based on colorimetric detection by optical absorption. A white light beam is guided through the microchannels containing the samples to analyse. The impinging light is filtered by a narrow passband optical filter at the wavelength defined by the biomolecule being analysed.