MAGNETIC FIELD DETECTION USING AN ACTUATED MICRO-SENSOR BASED ON PIEZO-RESISTOR TRANSDUCTION

Abstract

The measurement of an external magnetic field includes the implementation of as simple technique capable for transducing the defection induced by the Lorentz force, into electrical signals via advanced piezo-resistive technology. The piezo-resistive effect, which is highly dependent on the crystal lattice orientation, doping characteristics, and concentration levels of silicon, forms the core of this investigation. Polysilicon, renowned for its piezo-resistive properties, is utilized as the transducer material in this study. This paper focuses on the characterization of the transduction mechanisms and assesses the performance of several samples of piezo-resistors in converting cantilever displacement into measurable voltage outputs. The research outcomes illustrate that the variation in resistance (ΔRp %) exhibits a nonlinear relationship for different cantilever beam deflections. Utilizing a polysilicon piezo-resistor configured in a Wheatstone bridge, the proposed system effectively translates mechanical deflections into electrical measurements across different voltages and cantilever geometries. Remarkably, the highest sensitivity of approximately 64 mV/mT was attained, without amplification, using a thin polysilicon beam of 0.6 µm thickness embedded into a 2 µm thick silicon cantilever.