The development of miniaturized analytical systems brought several examples of novel platforms for a variety of applications in medical diagnostics, food safety, biodefense, agricultural and environmental monitoring. Portability, sensitivity, reliability, short turn-around-time, cost-effciency and connectivity are some of the critical assets that successful devices should possess. The advancements in such areas enabled the detection and analysis of biological and chemical agents outside the laboratory settings. In this thesis, we focus on the development of miniaturized sensor designs for on-site biological and chemical detection utilizing surface plasmon resonance sensing and infrared absorption spectroscopy. We proposed an integrated refractometric sensor combining a grating-coupled plasmon resonance surface with a planar photodiode which can find applications in lab-on-a-chip designs with high integration density. In order to address the use of lab-on-a-chip systems in point-of-care testing applications, we have developed a surface plasmon resonance imaging platform integrated with a smartphone. We have fabricated low cost and sensitive grating coupled surface plasmon resonance sensor chips using of-the-shelf optical storage discs. Then we have experimentally shown the capability of multiplexed detection and biomolecular sensing. Finally, we demonstrated infrared absorption spectroscopy on a mobile phone by developing a compact mid-infrared spectrometer that hosts a miniature uncooled thermal camera and a custom-designed silicon transmission diffraction grating.