Professor Xuewei Wang of Virginia Commonwealth University

"Ionophore-Based Optical Ion Sensing in Paper Microfluidics and Droplet Microfluidics"

The Wang group at VCU chemistry is interested in designing portable, wearable, implantable, and microfluidic chemical sensors for the diagnosis and management of diseases (https://www.xueweiwanglab.com). In this seminar, I will focus on ionophore-based optical ion sensors for non-invasive or minimally invasive electrolyte monitoring. In one direction, we developed inkjet-printable ion-selective optodes on porous substrates such as cellulose paper and fabrics. A nanolayer of rationally combined chemicals including a pH or solvatochromic dye, a hydrophobic ion exchanger, and an ionophore is printed onto polymer fibers in a precise, rapid, and reproducible manner, enabling calibration-free optical measurements of pH, Na + , K + , and other ions/polyions. In another direction, we developed a fluorescence-based electrolyte sensing platform in droplet microfluidics. The oil phase in droplet microfluidics is functionalized with a combination of hydrophobic sensing chemicals and becomes flowing sensors for aqueous droplets. Undiluted and untreated whole blood is successfully analyzed based on laser-induced fluorescence of the oil phase as the color and turbidity of the sample do not cause any optical interference to the oil sensors. Because the required blood volume for each measurement is << 1 microliter, this represents a minimally invasive diagnostic platform.