On-site portable single molecule fluorescence imaging device for high-sensitive and accurate target detection

Single molecule fluorescence detecting technique often has extremely high accuracy and sensitivity, thus it is often adopted in biomedicine detection, pollutant monitoring and chemical analysis. However, traditional single molecule fluorescence detecting devices often suffer from huge sizes and expensive costs, inevitably limiting their applications especially in on-site detections. In order to extend its application scope, we design a single molecule fluorescence imaging device (smFID), in which a laser is tilted illuminated on the sample chip, and a micro-objective is used for fluorescence signal collection, moreover, a smartphone with a filter is adopted to record the fluorescence images. According to the system design, smFID can reach a wide field of view of 1.5mm(2), a high resolution of 2.2 mu m and signal to noise ratio of similar to 22dB. Additionally, smFID is implemented in single molecule detection combining with the magnetic bead system, and its sensitivity can reach 1 nM and its detection range is wide from 1 nM to 1 mu M, which are much better than traditional chemical and optical methods. Considering smFID can be used for single molecule testing with compact configuration, fast speed, high sensitivity and accuracy, it is a favorable device potentially used in on-site single molecule sensing and imaging fields.