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A high-mode resonant silicon cantilever sensor is developed for detection of airborne nanoparticles (NPs) by monitoring the change in resonant frequency induced by an additional trapped NPs mass. A piezoresistive bridge is integrated in the cantilever for signal sensing. An electrostatic method is employed to trap the NPs on the cantilever surface. The experimental results indicate that the cantilever sensor operated in the second resonant mode exhibits higher quality factor than the fundamental mode, i.e. 2100, implying that a higher sensitivity, i.e. 32.75 Hz/ng, can be attained by operation at higher resonant mode. The influences of thermal, pressure and relative humidity, respectively, on the sensor have also been investigated with the purpose of observing the limitation of sensor sensitivity imposed by the environment.