%0 Journal Article
%T On-Chip Real-Time Chemical Sensors Based on Water-Immersion-Objective Pumped Whispering-Gallery-Mode Microdisk Laser
%A Liang Fu
%A Qijing Lu
%A Shusen Xie
%A Xiang Wu
%A Xiaogang Chen
%J Archive of "Nanomaterials".
%D 2019
%R 10.3390/nano9030479
%X Optical whispering-gallery-mode (WGM) microresonator-based sensors with high sensitivity and low detection limit down to single unlabeled biomolecules show high potential for disease diagnosis and clinical application. However, most WGM microresonator-based sensors, which are packed in a microfluidic cell, are a ˇ°closedˇ± sensing configuration that prevents changing and sensing the surrounding liquid refractive index (RI) of the microresonator immediately. Here, we present an ˇ°openˇ± sensing configuration in which the WGM microdisk laser is directly covered by a water droplet and pumped by a water-immersion-objective (WIO). This allows monitoring the chemical reaction progress in the water droplet by tracking the laser wavelength. A proof-of-concept demonstration of chemical sensor is performed by observing the process of salt dissolution in water and diffusion of two droplets with different RI. This WIO pumped sensing configuration provides a path towards an on-chip chemical sensor for studying chemical reaction kinetics in real time
%K whispering-gallery-mode (WGM)
%K sensor
%K water-immersion-objective (WIO)
%K microdisk
%K laser
%U https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6474083/