A lightweight resonance tracking system for piezoresistive microcantilever sensors

Abstract A lightweight resonance tracking system designed for precise monitoring of resonant frequency shifts in microcantilever sensors is introduced. The system integrates a Phase-Locked Loop (PLL)-based technique with a Python-based interface for real-time control and visualization. A tipless microcantilever sensor was tested under relative humidity (RH) conditions ranging from 63% to 90% to experimentally validate the system. The system demonstrated a sensitivity of 1.082 Hz/% RH and a Limit of Detection (LOD) of 1.89% RH. The silicon dioxide ( $$SiO_2$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>S</mml:mi> <mml:mi>i</mml:mi> <mml:msub> <mml:mi>O</mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:math> ) surface of the microcantilever is hygroscopic, allowing water vapor adsorption and causing frequency shifts. This effect is more pronounced at high humidity levels (&gt;80% RH) due to multilayer adsorption. These results confirm the reliability and precision of the system in detecting environmental changes. The findings highlight the potential of the developed system for applications in environmental monitoring, healthcare diagnostics, and industrial chemical sensing.