We report a smartphone based multispectral imager (MSI), a promising tool for point-of-care (POC) testing, which utilizes a bio-inspired MSI chip to capture both the spectral and spatial information of a target simultaneously. As the key component for compact MSI, the proposed MSI chip mimics the structure of an insect compound-eye, wherein each sub-eye responds to a specific spectral band. This could allow a smartphone to be transformed into an MSI device that could acquire a snap-shot spectral image in a single exposure. An orthogonal polarization imaging method is adopted, to boost the capability of the smartphone MSI for chemical analysis. The feasibility and application potential of the proposed device are demonstrated non-invasively for skin lesion and dental plaque analysis. The experimental results are consistent with the physiological expectations, validating the ability of the smartphone MSI for multispectral image acquisition and further analytical determination. The chemical analysis capability, portability and cost-effectiveness of the smartphone MSI make it a promising analytical tool for POC testing, from chemical analysis to in vivo pathological diagnosis.