Miniatured dual-field microscope for intelligent Marine algae detection, sizing and counting in a microfluidic chip.

On-site and accurately detecting, sizing and counting living algae are greatly needed under International Ballast Water Convention, yet still challenging due to the lack of miniatured device. In this paper, a miniatured microscope that has both blue view field and fluorescence field was developed. Dual-view-field with one exciting light is achieved by using a beam splitter to direct the light into two mini cameras. Due to the strong intensity of the exciting blue light, the excited fluorescence light is overridden by the blue light and cannot be observed in the blue-field camera. To image the chlorophyll fluorescent light, a chlorophyll filter is placed before the fluorescence-field camera. An intelligent algorithm was developed for automatically sizing and counting the detected algae. It was experimentally found that both the total algae and the living algae can be clearly shown in the cameras. The counting accuracy is larger than 89 %. The maximum allowable detection speed is determined by the diameter of the algae, the frame rate (fps) and resolution of the two mini cameras. The total size of the device is 260 mm ∗ 260 mm ∗ 280 mm (length ∗ width ∗ height) and is thus suitable for on-site evaluation of the living status of algae in treated ship's ballast water.