Ultrasensitive Piezoelectric-Based Microcantilever Biosensor: Theory and Experiment

Microcantilever (MC)-based sensors have become an advantageous tool for detection of ultrasmall masses and biological species. Exploiting high affinity of biomolecules, MCs offer a simple, inexpensive, and highly sensitive platform for high throughput diagnosis and analytical sensing. A number of methods have been reported targeting sensitivity enhancement of MC-based systems including geometry modification, employing nanoparticle-enhanced MCs, and operating MCs in lateral and torsional modes. High mode resonating MCs have been reported as a promising sensitivity enhancement method. Although being investigated, there have not been enough analytical high fidelity models describing all dynamics and behavior of MCs operating in high modes with experimental proof. In this study, experimental results of a piezoelectric self-sensing MC operating as a biological sensor at ultrahigh mode along with theoretical verification are presented. Effect of absorbed mass on the frequency shift was investigated using self-sensing and optical measurement methodologies. Mode convergence theory was adopted in order to get the best estimation of resonance frequencies at different modes. Amino groups of aminothenethaiol solution are immobilized over MC. Shift in resonance frequencies in higher modes are measured and the quality factor is calculated proving the fact that sensitivity of MC to detect absorbed masses enhances as the number of modes increases.