Droplet Enhanced Fluorescence for Ultrasensitive Detection Using Inkjet.

A fluorescence enhanced phenomenon was found within a micrometer-sized liquid droplet, and it was adopted to construct droplet enhanced fluorescence (DEF) for ultrasensitive fluorescence detection. In this paper, an inkjet was utilized to eject perfect spherical droplets to construct a microspherical resonator and to develop a DEF system. It was utilized to implement ultrasensitive fluorescence detection in a liquid specimen with a volume of several microliters. The DEF detection of fluorescent molecules, fluorescein sodium, was used as a model to validate the proposed enhanced fluorescence detection method. A low limit of detection (LOD) for fluorescein sodium of 124 pM was obtained. The sensitive detection of single stranded DNA (ssDNA) was experimentally completed, with a wide range of linearity with a LOD of 312 pM. The proposed mechanism can be used as an ultrasensitive detection technique for analyzing microliters of liquid samples.