(Invited) Droplet Microfluidic Devices for Chemical Sensing Application; 1) Paper Digital Microfluidics and 2) Modular Microfluidics

Abstract

In this presentation, I want to share my recent research works about microfluidics chemical sensors. There are two topics; 1) Paper Digital Microfluidics and 2) Modular Microfluidics. First, the double-sided electrohydrodynamic jet printing of circuitry using silver nanowires (AgNWs) and dispensing of high viscosity silver nanoparticles (AgNPs) is demonstrated in the fabrication of an array of electrodes (3D circuitry) on a single sheet of paper. The penetration of AgNW ink through the paper’s thickness by capillary imbibition allows for multilayer electrical access to connect the individual electrodes. This makes it an automated and efficient choice as the functional area of the device is conserved and the surface of the paper is preserved. This allows for two-dimensional droplet manipulation on a paper-based digital microfluidics (PBDMF) platform. Compared to printed circuit board technology, paper-based electronics offer a range of desirable properties: they are light weight, portable, economical, flexible, biodegradable, and the materials are abundantly available. The fabricated PBDMF chip is demonstrated to be a low-cost, fully reconfigurable, and disposable point-of-care diagnostic platform for the environmental sensing of pesticide using organophosphorus hydrolase enzyme through colorimetric detection via smartphone. Second, we designed a modular microfluidic system for generating droplets using a three-dimensional (3D) printer. This system was manufactured as a modular system with multipurpose droplet generation flexibility. We fabricated various microfluidic modules with different functions, such as droplet generation, mixing, and electrical field generation. We demonstrate flexibility of this system by generating various types of emulsion droplets by changing the combination of modules. Moreover, the generated emulsion droplets showed electrodydrodynamic phenomena, such as the shape deformation, coalescence, breakup, and others, which can be applied to material synthesis, chemical sensing and reaction, bioassay and other applications. This modular microfluidic system is suitable to achieve various purpose as desired by the end user.