The images projected by scanned laser pico-projectors (SLPPs) contain speckle noise caused by the reflection of the high coherent laser light source from the projection screen. A speckle pattern can be used to detect the concentration of liquid solution with nanoparticle. Three samples: solid solution, liquid solution, and collagen solution are tested. The experimental results show that the green laser within the SLPP provides a better sensitivity and resolution than the red or blue lasers. In solid solution measurement, different concentrations of nanoparticles embedded in a poly (methyl methacrylate) (PMMA) matrix are tested. In liquid solution measurement, different concentrations of nanoparticles dissolved in deionized water are also tested. Finally, the system shows ability to measure the collagen concentrations from 0.125% to 0.025%. Accordingly, the proposed system provides a viable, low-cost solution for high-sensitivity in biomedical, chemical and environmental applications.