Directed Molecular Collection by E-Jet Printed Microscale Chemical Potential Wells in Hydrogel Films

A facile approach to locally concentrate analytes of interest will significantly enhance miniaturized, integrated chemical-analysis systems. Here, the directed analyte transport and concentration using ≈200 µm-diameter E-jet printed chemical potential wells in a polyacrylamide hydrogel is demonstrated. Using a cationic well as the model system, anionic analytes are accumulated into a microscale area with a local concentration enhancement of >50-fold relative to the surrounding area. By downscaling the diameter of the chemical potential well from a few millimeters to 100s of micrometers, it is found, using both fluorescence and Raman microscopy, that the molecular collection capacity of the well is greatly improved. Additionally, it is shown that molecules can be simultaneously transported and concentrated to arrays of microscale regions using an array of microscale chemical potential wells. This approach enhances many-fold the limit of detection, enables the formation of microscale potential well arrays with a variety of chemical properties, and provides a novel microscale molecular manipulation technique as an alternative to traditional microfluidic-based systems.