Fig. 7
Mechanical connectivity and geometric width of cantilevers enhance force detection sensitivity. a Schematic diagram showing attachment of molecules (yellow) to the nanomechanical cantilever surface. b The sketch shows a close-up image of the ligand–receptor complex on the nanomechanical cantilever surface as used for the detection of mechanical response. In a and b, the uncoated areas on the cantilevers (yellow orange) were passivated to block nonspecific interactions and the mechanical response was monitored in parallel using time-multiplexed optical beam detection on a single photodetector. c The mechanical force from 1 µM Van against three separate experiments (green, red and blue). d The mechanical force from 1 µM Van against broad geometrical width (purple) and narrow geometrical width (green) of nanomechanical cantilever sensors. In c and d, the shaded areas represent the time frame during which the phosphate-buffered saline solution was injected without analytes to establish a baseline. The reference signal is shown in black and the negative signal is associated with compressive mechanical force on the gold top surface causing the cantilever to bend down. The results show that narrow cantilevers have the outstanding sensitivity and robustness to detect vancomycin. In addition, the results show that continuous mechanical connectivity is a relevant control parameter of signal sensitivity and reproducibility
