AFM Probe Optomechanical Resonator High Frequency Sensitivity

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Solution Overview

Problem

Current atomic force microscopy probes face limitations in increasing resonance frequency and measurement sensitivity, particularly due to the challenges of miniaturization, which reduces transduction capacity and limits detection of mechanical oscillations at high frequencies and low force resolutions.

Innovation Solution

A probe with an integrated optomechanical resonator that combines mechanical and optical volume vibration modes, utilizing optomechanical coupling for both detection and actuation, allowing for higher resonance frequencies and improved sensitivity without the need for dedicated excitation means.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the dimensions of the mechanical resonator are reduced to increase the natural resonant frequency, then the resonance frequency increases, but the transduction capacity decreases and measurement sensitivity is lost

Engineering Contradiction:
Improveresonance frequencyVSAvoidmeasurement sensitivity
Core Design Contradiction:
SpeedVSMeasurement precision

Solution Approach 1:

The patent merges mechanical resonance and optical resonance into a single integrated optomechanical resonator. The mechanical resonator and optical resonator are coupled such that mechanical vibrations modulate the optical resonance, enabling high-frequency detection while maintaining sensitivity through optical transduction rather than direct mechanical sensing.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces an optical field as an intermediary to transduce mechanical vibrations. The mechanical resonator's vibrations modulate the optical resonance frequency or intensity, which can be detected with high precision. This optical intermediary overcomes the limitations of direct mechanical transduction at high frequencies.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Speed

If conventional optical detection methods are used on miniaturized cantilevered beams, then the resonance frequency increases, but the optical diffraction limit prevents effective detection

Engineering Contradiction:
Improveresonance frequencyVSAvoiddetection capability
Core Design Contradiction:
SpeedVSDifficulty of detecting and measuring

Solution Approach 1:

The patent combines mechanical and optical resonance in a single integrated structure, eliminating the need for separate detection optics. The optomechanical resonator itself serves as both the mechanical element and the optical cavity, allowing detection without being limited by the diffraction of external light beams.

Inventive Principle:
Principle #5Merging (Combining)

3Speed

If electrostatic actuation with capacitive sensing is used to increase resonance frequency, then the resonance frequency increases, but the sensitivity limit degrades

Engineering Contradiction:
Improveresonance frequencyVSAvoidsensitivity limit
Core Design Contradiction:
SpeedVSMeasurement precision

Solution Approach 1:

The patent replaces electrostatic capacitive sensing with optical resonance-based sensing. The optical resonator's high Q-factor enables detection of mechanical vibrations with sensitivity that does not degrade with frequency increases, overcoming the limitations of electrostatic transduction.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Speed

If bending mechanical vibration modes are used with optical resonators, then the resonance frequency can be increased, but the probe dimensions must be reduced to a scale incompatible with industrial manufacturing

Engineering Contradiction:
Improveresonance frequencyVSAvoidindustrial manufacturing compatibility
Core Design Contradiction:
SpeedVSEase of manufacture

Solution Approach 1:

The integrated optomechanical resonator serves multiple functions simultaneously: it acts as both the mechanical resonator for force sensing and the optical resonator for high-sensitivity detection. This multi-functionality eliminates the need for separate miniaturized components, making the device compatible with standard semiconductor manufacturing processes while achieving high resonance frequencies.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables higher frequency measurements and enhanced sensitivity, achieving resonance frequencies between 1 MHz and 10 GHz with improved force measurement resolution, overcoming the limitations of prior art by maintaining industrial compatibility and cost-effectiveness.

Implementation Method 1

A probe with an integrated optomechanical resonator that combines mechanical and optical volume vibration modes, utilizing optomechanical coupling for both detection and actuation

Methodology Applied
Scientific EffectOptomechanical coupling:

Implementation Method 2

the optical resonator is coupled to the mechanical resonator and used to detect mechanical deformations of the resonator

Methodology Applied
Scientific EffectOptical detection:

Implementation Method 3

A classic operating mode is oscillatory mode, in which the mechanical resonator vibrates at a frequency close to one of its natural frequencies

Methodology Applied
Scientific EffectMechanical resonance: Resonance

Implementation Method 4

The vibrating tip interacts with the attractive and/or repulsive forces present on the surface of the material

Methodology Applied
Scientific EffectSurface interaction forces: Van der Waals Force

Data Source

PatentEP3571513B1Probe for atomic force microscope equipped with an optomechanical resonator and atomic force microscope comprising such a probe
Publication Date: 2023.11.08 VMICRO
  • EP3571513B1 patent drawingFigure 1~2B
  • EP3571513B1 patent drawingFigure 3
  • EP3571513B1 patent drawingFigure 4~5

AI summary

The invention relates to a probe (100) for an atomic force microscope comprising an optomechanical resonator (102) and a probe tip (103) protruding from the resonator, wherein the resonator is coupled to optical means configured to emit a light beam incident on the resonator and to receive a light beam emerging from the resonator. The optomechanical resonator comprises a body configured to resonate both in a volume mechanical vibration mode and in a volume optical vibration mode, wherein the optical vibration mode is coupled to the mechanical vibration mode such that a mechanical deformation of the resonant body in the mechanical vibration mode induces a change in the light transmission state in the optical vibration mode, which modifies the emerging light beam.