Self-Sensing Micro- and Nanocantilevers with Attonewton-Scale Force Resolution

Abstract

Thin, piezoresistive silicon cantilevers are shown to provide unprecedented sensitivity for force detection in an integrated, self-sensing, readily scalable configuration. The devices realized herein are patterned from single-crystal Si epilayer membranes utilizing bulk micro- and nanomachining processes. We demonstrate an electrically transduced force sensitivity of 235 aN/Hz1/2 at room temperature and 17 aN/Hz1/2 at 10 K. Enhancement of the p+ piezoresistive gauge factor is observed at cryogenic temperatures. The results are employed to elucidate the ultimate, low-temperature sensitivity attainable from self-sensing nanoelectromechanical systems utilizing displacement transduction based upon semiconducting piezoresistors.

Piezoelectric nanoelectromechanical resonators based on aluminum nitride thin films

“…These miniaturized nanoscale devices, particularly cantilever and beam flexural-mode resonators, have enabled the demonstrations of single-molecule mass sensors 10 and single-cell-level force sensors. 11 For NEMS resonators in such applications, piezoelectric actuation appears to be particularly advantageous compared to the more conventionally employed magnetomotive, 10 electrostatic, 12 and electrothermal 13 excitations. Among its attributes are intrinsic integrability, high efficiency and electrical tunability, low power consumption, and low thermal budgets for materials processing permitting post-CMOS integration.…”

Design optimization of piezoresistive cantilevers for force sensing in air and water

“…Thermomechanical noise 27,28 and fluid damping noise 29 are not included in the present analysis but should be considered in certain applications, such as those requiring subpiconewton force resolution. 30 These other noise sources will be briefly discussed at the end of this section.…”

Fast on-wafer electrical, mechanical, and electromechanical characterization of piezoresistive cantilever force sensors

“…These include the development of atomic force microscopy (AFM) probes, [5][6][7][8] probes for magnetometry, 9 the high force sensitivity achievement with <100 nm thin cantilevers, 10 the characterization of low force electrical contacts 11 and the study of the ultimate piezoresistive sensitivity at low temperatures. 12 We have previously presented the fabrication of cantilevers made of polycrystalline silicon using a commercial CMOS process flow together with integrated read-out a) Electronic mail: joan.bausells@imb-cnm.csic.es. circuitry.…”

“…That can be done by performing an accurate deflection of the cantilever while recording the resistance variation (i.e., the voltage variation on a Wheatstone bridge). In order to deflect the cantilever with high accuracy, various approaches have been used, such as a needle mounted on a bimorph piezodisk, 17 a calibrated piezotube, 18 an AFM in contact mode 12 or in tapping mode, 19 etc. A parallel approach, only valid for very low stiff devices, measures the resonant thermomechanically-driven displacement fluctuations.…”