Highly Sensitive and Miniaturized Fluorescence Detection System with an Autonomous Capillary Fluid Manipulation Chip

This paper presents a novel, highly sensitive and ultra-small fluorescent detection system, including an autonomous capillary fluid manipulation chip. The optical detector integrates a LED light source, all necessary optical components, and a photodiode with preamplifier into one package of about 2 cm × 2 cm × 2 cm. Also, the low-cost and simple pumpless microfluidic device works well in sample preparation and manipulation. This chip consists of capillary stop valves and trigger valves which are fabricated by lithography and then bonded with a polydimethylsiloxane-ethylene oxide polymer polydimethylsiloxane (PEO-PDMS) cover. The contact angle of the PEO-PDMS can be adjusted by changing the concentration of the PEO. Hence, the fluidic chip can achieve functionalities such as timing features and basic logical functions. The prototype has been tested by fluorescence dye 5-Carboxyfluorescein (5-FAM) dissolved into the solvent DMSO (Dimethyl Sulfoxide). The results prove a remarkable sensitivity at a pico-scale molar, around 1.08 pM. The low-cost and miniaturized optical detection system, with a self-control capillary-driven microfluidic chip developed in this work, can be used as the crucial parts in portable biochemical detection applications and point of care testing.