A portable fluorescent sensor for on-site detection of microalgae

This work reports the development of a portable and low cost fluorescent sensing system with a disposable microfluidic chip for on-site detection of a microalgal sample and its concentration. The sensor system has multiple light emitting diodes (LEDs) for excitation and a photodetector for measuring a fluorescent signal from a microalgal sample. The concentration of a microalgal sample is determined by measuring the fluorescent signal emitted by chlorophyll a. A dichroic filter and a color filter are also added to allow only the fluorescent signal from chlorophyll a to pass through the photodetector. The microfluidic chip consists of a glass slide and a PDMS channel with a vacuum pump, which collects a small volume of the microalgal sample (<101 mu l). The fluorescent sensor was characterized with varying concentration of microalgal samples and demonstrated its capability of measuring microalgal concentrations. The sensor was also tested with microalgal samples mixed with different turbidity water to validate its selectivity. The results show that the fluorescent detection of microalgal concentration is not influenced by the turbidity level of the sample solution. The developed system can be used for on-site screening and monitoring of microalgal population with an integrated excitation and detection circuitry. (C) 2015 Elsevier B.V. All rights reserved.