Nonlinear nanomechanical oscillators for ultrasensitive inertial detection
A system for ultrasensitive mass and/or force detection of this invention includes a mechanical oscillator driven to oscillate in a nonlinear regime. The mechanical oscillator includes a piezoelectric base with at least one cantilever resonator etched into the piezoelectric base. The cantilever resonator is preferably a nonlinear resonator which is driven to oscillate with a frequency and an amplitude. The system of this invention detects an amplitude collapse of the cantilever resonator at a bifurcation frequency as the cantilever resonator stimulated over a frequency range. As mass and/or force is introduced to the cantilever resonator, the bifurcation frequency shifts along a frequency axis in proportion to the added mass.
1. A method for ultrasensitive mass and force detection comprising:
mounting a cantilever resonator on a piezoelectric transducer;
driving the piezoelectric transducer to oscillate the cantilever resonator with an amplitude over a frequency range;
deflecting a laser beam focused at an angle on the cantilever resonator;
projecting the deflected laser beam as a spot with an oscillation amplitude onto a screen; and
detecting a bifurcation frequency of the cantilever resonator as a drop in the oscillation amplitude.
2. The method of claim 1 further comprising:
detecting the bifurcation frequency with a spot photodetector.
3. The method of claim 1 , wherein the angle in the deflecting step is greater than ten degrees.
4. The method of claim 1 , wherein the cantilever resonator is driven to oscillate in a nonlinear range.
5. The method of claim 4 , wherein the amplitude of the cantilever resonator is greater than ten micrometers.
6. The method of claim 1 , wherein a digital programmable sweep generator drives the piezoelectric transducer to oscillate the cantilever resonator over the frequency range.
7. The method of claim 1 , wherein the mounting step further comprises:
mounting an array of cantilever resonators etched on a chip on the piezoelectric transducer.
8. A system for ultrasensitive mass and force detection comprising:
a piezoelectric base;
a cantilever resonator including a free end and a fixed end, the fixed end attached to the piezoelectric base and the free end extending away from the piezoelectric base;
a transducer connected to the piezoelectric base to drive the cantilever resonator to oscillate at an amplitude and a frequency;
a digital programmable sweep generator in communication with the transducer to excite the cantilever resonator over a frequency range;
a laser including a laser beam focused at an angle to the cantilever resonator;
wherein the digital programmable generator sweeps the transducer across the frequency range to determine a bifurcation frequency and the system detects an external stimuli by measuring shifts of the bifurcation frequency.
9. The system of claim 8 wherein the transducer drives the cantilever resonator into a nonlinear resonance.
10. The system of claim 8 , wherein the cantilever resonator is a nonlinear resonator with a nonlinear elasticity.
11. The system of claim 8 , wherein the piezoelectric base and the transducer are combined as a piezoelectric transducer.
12. The system of claim 8 further comprising:
an array of cantilever resonators attached to the piezoelectric base.
13. The system of claim 8 , wherein the cantilever resonator is etched into the piezoelectric base.
14. The system of claim 8 , wherein the cantilever resonator oscillates at an amplitude of greater than 5% of a length of the cantilever resonator.
15. The system of claim 8 , wherein the cantilever resonator includes an asymmetric geometrical design.
16. The system of claim 15 , wherein the cantilever resonator includes an out-of-plane deformation.
17. The system of claim 8 , wherein the cantilever resonator functions as a mechanical demodulator converting the amplitude into a measurable DC signal.
18. A system for ultrasensitive mass and force detection comprising:
a piezoelectric base;
a transducer connected to the piezoelectric base;
a cantilever resonator including a free end and a fixed end, the fixed end mounted to the piezoelectric base and the free end extending away from the piezoelectric base;
a driver in electrical communication with a modulated light source and a projecting optics, the modulated light source and the projecting optics directing light on the cantilever and the piezoelectric base;
a digital camera, an imaging optics and a spatial filter positioned over the piezoelectric base and the beam to capture a reflected light from the piezoelectric base and the cantilever; and
wherein the transducer drives the cantilever into a nonlinear resonance and the system detects an external stimuli by measuring shifts in a bifurcation point.
19. The system of claim 18 , wherein the cantilever resonator is a nonlinear resonator with a nonlinear elasticity.
20. The system of claim 18 , wherein the cantilever resonator includes an asymmetric geometrical design and an out-of-plane deformation.