Embodiments of this invention relate generally to a method for detection of pathogens, biomarkers, or any compound using data fusion and machine learning. The method includes generating, with a first miniature UV absorption spectrometer of a multi-spectral optical device, a first absorption spectral output based on receiving an absorbance light channel from a sample, generating, with a second miniature UV fluorescence spectrometer of the multi-spectral optical device, a second emission spectral output based on receiving an emission light channel from the sample and performing, with the multi-spectral optical device, data fusion between the first absorption spectral output and the second emission spectral output to generate fused data.