Experimental and Numerical Studies of Cantilever Sensors

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Existing methods for detecting heavy metals in fresh water require samples be collected and sent to specialized laboratories to be analyzed. Such a procedure is time consuming and expensive. Portable devices containing arrays of microcantilever sensors capable of detecting several analytes at one time could, one day, be used for performing a complete heavy metal analysis of water onsite, quickly, cost effectively, and with minimal user training. Microcantilever sensors are small cantilevers approximately 400 microns long, 50 microns wide, and 1 micron thick functionalized to be receptive to specific target analyte. Because of their small size, hundreds of cantilevers can be incorporated in an area the size of a dime. Although cantilever sensors offer all the necessary criteria for satisfying the above goal, their reproducibility has prevented them from being implemented into commercial devices. The principle objective of this application is to investigate, using an innovative combination of experimental observations and numerical modeling and simulations, the factors that affect the reproducibility of cantilever sensors by: exploring the materials science issues such as the morphology of the thin Au film used to anchor the sensing layer; understanding how analyte flows within the sensor cell using fluid dynamics simulations; and studying the host/guest reactions of new calixarene sensing layers designed to detect specific heavy metals. The results of the proposed work will quicken the application of cantilever sensors into commercial devices for a variety of applications from detecting viruses to trace gases from explosive devices. Understanding the materials science issues will benefit a variety of sensor technologies that translate a chemical or biological stimulus into a mechanical response. The long term objective of developing portable devices for measuring heavy metal levels in fresh water will not only benefit Canada but also governments and environmental protection agencies worldwide as the contamination of our freshwater sources continues to grow. As a second objective, which will rely on my expertise in scanning probe microscopy, we will endeavour to be the first to investigate the validity of new theories of friction and frictional aging. Friction and frictional aging are fundamental properties of materials with far reaching implications from machine wear to the motion of tectonic plates. Understanding these fundamental concepts ultimately leads to the ability to control them which could have significant implications in many technological applications from developing more efficient engines to more wear resistant tools. We will also attempt to develop a new theory to better interpret dynamic force spectroscopy measurements. If successful the results of this work will allow the strength of molecular and biological bonds to be measured with unprecedented accuracy.