Droplet-Based Analytical Chemistry Platforms Using Superhydrophobic and Superamphiphobic Surfaces

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Our laboratory is interested in the development of novel separation and detection methods for chemical analysis. Chemical analysis forms the basis for discovery in a wide variety of disciplines (e.g. environmental, medical and “omics” related research areas). The development of analysis systems that are faster, require less sample with increased sensitivity are in constant demand and become critical to probing e.g. biological and chemical systems in a variety of matrices. Our laboratory will develop droplet-based (digital) microfluidic platforms that combine low friction surfaces (superhydrophobic and super amphiphobic) with both magnetic and gravity-based droplet actuation and apply them to rapid/sensitive chemical analysis. My program will involve the synthesis and characterization of novel inorganic and polymer-based materials for low friction surface coatings and probe novel microfabrication methodologies to enable facile device fabrication (e.g. laser micromachining). Superhydrophobic/amphiphobic surfaces are characterized by extremely high contact angles (150 o) when droplets, of for example water, are placed upon their surface. The superhydrophobicity/amphiphobicity is generated through a combination of both surface chemistry and surface topography. The minimal surface adhesion enables the manipulation of droplets through the application of small forces (< 1 µN) on the droplet. A droplet can be rapidly actuated by introducing superparamagnetic particles to an aqueous droplet on a low friction surface, and applying a magnetic field (with speeds in excess of 50 cm/sec!). Alternatively we have shown that droplets can be manipulated using dissolved paramagnetic salts even though their magnetic susceptibility is approximately 10,000X less than that of the superparamagnetic particles. Paramagnetic particles can be functionalized with proteins, stationary phases, or with antibodies to conduct chemistry within the individual droplets. In this way multiplexed sample preparation prior to chemical analysis can be conducted (e.g. solid phase extraction, immuno-capture or derivatization). We will leverage my research group’s and our collaborator’s experience in mass spectrometry (MALDI and DESI-MS), fluorescence, electrochemical and absorbance detection to analyze of a variety of analytes (e.g. biomarkers, biosynthetic enzymes, environmental contaminants, etc.) within droplets following sample preparation. Our laboratory collaborates with a number of academic and industrial partners (e.g. NSERC Engage, Strategic and CREATE programs) to further augment and internationalize the training of researchers involved within my research program. The combination of experiences in microfabrication, microfluidics, mass spectrometry and surface science will provide students with a skill set relevant to the industrial, governmental and academic sectors.