System for wide frequency dynamic nanomechanical analysis
View Patent ↗Dynamic nanomechanical analysis of a sample is performed by using a cantilever probe that interacts with the sample using a force applied across a wide range of frequencies that includes frequencies greater than 300 Hz. The motion of the cantilever probe is detected in response to the applied force over the range of frequencies and analyzed over at least a portion of the wide range of frequencies to determine a mechanical response of the sample, preferably including quality factor and modulus of the sample. The analysis of the motion of the cantilever probe is preferably performed in terms of amplitude, phase, and frequency of both the probe and the sample and preferably, where the applied force is analyzed to determine both a real and an imaginary modulus of a mechanical response of the sample. Preferably, the force is applied so as to produce a minimum of phase and amplitude response variation in the absence of the sample. Furthermore the motion of the cantilever can be flexural or torsional and combinations thereof.
1. A method of performing dynamic nanomechanical analysis of a sample comprising the steps of:
providing a cantilever probe;
interacting the cantilever probe with a sample by applying a force across a wide range of frequencies such that the applied force produces a phase response variation in the absence of contact of the tip with the sample that is less than ±10° over at least 10 kHz of the range of frequencies;
detecting a motion of the cantilever probe in response to the applied force over the range of frequencies; and
analyzing the motion of the cantilever probe over at least a portion of the range of frequencies to determine a mechanical response of the sample.
2. The method of claim 1 , further comprising performing the steps at a plurality of positions with respect to the sample.
3. The method of claim 1 , further comprising performing the steps at a plurality of temperatures.
4. The method of claim 1 , further comprising performing the steps at a plurality of environmental conditions.
5. The method of claim 1 , wherein the step of detecting the motion detects a value selected from the set consisting of: a motion of the cantilever probe, a motion of the sample, a deformation of the sample, or any combination thereof.
6. The method of claim 1 , wherein the step of interacting the cantilever probe with the sample is performed by applying a preset force selected from the set including: a force applied in a DC mode, a force applied in an AC mode, or any combination thereof.
7. The method of claim 6 , further an AC force that perturbs the preset force over a continuous wide frequency range.
8. The method of claim 1 , wherein the step of detecting a motion detects a motion of both the cantilever probe and a deformation or motion of the sample.
9. The method of claim 1 , wherein the step of analyzing is performed in terms of amplitude, phase and frequency of the cantilever probe and in terms of amplitude, phase and frequency of the sample.
10. The method of claim 8 , wherein the step of analyzing is performed in terms of: a three-dimensional motion of the cantilever probe, a three-dimensional deformation of the sample, or a combination of both the motion of the cantilever probe and the deformation of the sample.
11. The method of claim 1 , wherein the step of analyzing is performed in terms of amplitude, phase, and frequency.
12. The method of claim 1 , wherein the step of analyzing is performed in terms of the free decay of the cantilever probe after the force is withdrawn.
13. The method of claim 1 , further comprising choosing a tip of the cantilever probe from the group consisting of a stylus shaped tip and a ball shaped tip.
14. The method of claim 1 , wherein the sample is provided in a deformable shape such that the step of interacting the cantilever probe is accomplished through contact of a probe tip to the deformable sample to cause deformation across the wide range of frequencies.
15. The method of claim 14 , wherein the deformable shape is selected from the set consisting of: a secondary cantilever with at least one end fixed, a membrane, a bridge, or any combination thereof.
16. The method of claim 1 , wherein the step of detecting is accomplished by a primary displacement transducer detecting the cantilever probe motion.
17. The method of claim 8 , wherein the step of detecting is accomplished by a secondary displacement transducer detecting the motion and deformation of a deformable sample.
18. The method of claim 1 , wherein the mechanical response includes a mechanical property of the sample that is selected from the set consisting of: mechanical quality, elasticity, viscoelasticity, or any combination thereof.
19. The method of claim 1 , wherein the mechanical response includes a mechanical property of the sample that is selected from the set consisting of: mechanical quality, elasticity, viscoelasticity, or any combination thereof that is determined as a function of temperature, frequency or any combination thereof.
20. The method of claim 1 , wherein the step of providing a cantilever probe includes providing a cantilever probe selected from the set including: a cantilever only and a cantilever with a tip operably attached to the cantilever.
21. The method of claim 1 , wherein the step of providing the cantilever probe includes providing a cantilever probe with an active piezoelectric layer coated on at least a portion of a surface of the cantilever probe and the piezoelectric layer is utilized to apply the force in the step of interacting the cantilever probe with the sample in the range of frequencies.
22. The method of claim 1 , wherein the force applied to the cantilever probe is an amount between 10 −6 and 1000.0 micro Newtons.
23. The method of claim 1 , wherein the step of interacting the cantilever probe with the sample is accomplished by applying the force through a combination of flexural and torsional deformation of the cantilever probe.
24. The method of claim 23 , wherein the step of providing the cantilever probe includes providing a cantilever probe with an active piezoelectric layer coated on at least a portion of a surface of the cantilever probe and the piezoelectric layer is utilized to apply the force in the step of interacting the cantilever probe with the sample.
25. The method of claim 24 , wherein the active piezoelectric layer comprises at least two symmetric strips positioned along an axis of the cantilever probe and wherein electrodes operably associated with each strip each receive a drive signal out of phase with any other drive signals to excite torsional deformation of the cantilever probe, and each electrode receives a drive signal in phase with the other drive signals to excite flexural deformation of the cantilever probe.
26. The method of claim 25 , wherein a magnitude of the drive signal in-phase and out of phase drives to individual piezo elements is adjustable independently.
27. A method of performing dynamic nanomechanical analysis of a sample comprising the steps of:
providing a cantilever probe:
interacting the cantilever probe with a sample by applying a force across a wide range of frequencies such that the applied force produces a phase response variation in the absence ot contact of the tip with the sample that is less than ±10° over at least 10 kHz of the range of frequencies:
detecting a motion of the cantilever probe in response to the applied force over the range of frequencies; and
analyzing the motion of the cantilever probe over at least a portion of the range of frequencies to determine a mechanical response of the sample, wherein the step of analyzing is performed in temis of sample oscillation after the force is withdrawn in order to derive the mechanical response in terms of at least one of the following properties: elasticity, anelasticity, or viscoelasticity of the sample.