Frequency-addressed NEMS arrays for mass and gas sensing applications

This paper reports the design, fabrication and characterization of NEMS resonator arrays along with their associated readout scheme enabling the probing of all the resonators within an array. The successful monitoring of arrays of 20 NEMS in both air and vacuum is presented and the significant advantage these arrays provide over individual resonators for mass and gas sensing is discussed. Arrays of 20, 49 and 100 resonators have been designed and characterized in terms of Signal to Background Ratio (SBR) of the NEMS frequency response and Allan Deviation (ADEV) for the frequency stability of the resonators. While probing an array in closed loop, mass additions onto the NEMS were simulated by electrostatically-induced frequency shifts. These shifts were applied simultaneously on the entire array to demonstrate the ability of this system to track the complete array in real time. On the other hand, a noise reduction at short integration times by a factor close to √N, where N is the number of resonators, has been obtained by averaging all the resonators' signal. The ability to control arrays of NEMS with a simplified routing and a reduced number of electrical connections is demonstrated and the great potential of NEMS arrays for gas and mass sensing applications is highlighted.