Carbon dioxide sensors have potential applications in medical diagnoses, health care, environmental monitoring, food and medicine industry. In recent years, many novel biological, physical and chemical sensors have employed microcantilevers due to their simplicity, ease of fabrication and integration with electronics. This paper presents design, modeling and simulation of a microcantilever working in dynamic mode for CO 2 gas sensing with electromagnetic actuation and capacitive sensing using comb fingers. The sensor is based upon 0.35 micron CMOS technology. CoventorWare and MATLAB have been used as simulation software. According to the developed model and simulation results the resonator has a quality factor of 3333 in air and mass sensitivity of 3.2 Hz/ng. © 2011 IEEE.