| A sensing scheme involving a commercially available piezoelectric microcantilever and accompanying self-sensing circuit is investigated for atomic force imaging in intermittent contact (tapping mode) and mercury vapor detection. The development of a self-sensing circuit and its application are the main focus of this thesis. The piezoelectric self-sensing scheme is a stepping stone for achieving simple, extremely sensitive, compact, and low-power-consuming sensors.; Typically, atomic force microscopy is accomplished through monitoring the amplitude of oscillation optically (using a laser and a photosensitive detector). This involves the tedious task of laser alignment. Piezoelectric sensing eliminates the need for the optical system. Previous research involving a piezoelectric sensing scheme has been limited by stress in the cantilevers, thickness and size of the cantilevers, un-optimized electrical trace design, and/or a lack of a probing tip. Comparisons of typical amplitude detection by optical means versus the new piezoelectric sensing are made. Tests indicate amplitude resolution with self-sensing to be as good or better than optical detection, and sensitivities to be twice as good, with the same type cantilever.; The same piezoelectric sensing platform was used for mercury vapor detection, where changes in oscillatory amplitude are the result of shifts in the resonance frequency. Mercury vapor adsorbed onto the gold electrodes of the cantilever creates a mercury gold amalgamation. The amalgam increases the cantilever stiffness and, therefore, the resonance frequency. |
