Miniaturized Optical Tweezer Array with Reflective Elements

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Solution Overview

Problem

Existing optical tweezers systems face limitations in generating efficient 3-dimensional traps due to high NA optics requirements, limited field of view, and difficulty in miniaturization, as well as inefficiencies in trap addressing and alignment, particularly when trying to create large arrays of traps.

Innovation Solution

The use of an array of micro-lenses combined with an array of micro-mirrors to counterbalance scattering forces, allowing for efficient 3-dimensional optical trapping without the need for high NA objectives, and incorporating optical valves for independent trap addressing and miniaturization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high NA objectives are used to create 3D optical traps, then trapping efficiency is improved, but device complexity and difficulty of miniaturization increase

Engineering Contradiction:
Improvetrapping efficiencyVSAvoidoptics complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the optical system into multiple micro-lens elements arranged in arrays, where each micro-lens creates individual focal points that serve as optical traps. This segmentation replaces the need for a single high-NA objective with multiple lower-NA micro-lenses, enabling miniaturization while maintaining trapping capability through distributed focal points

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from using a single high-NA objective in one dimension to using arrays of micro-lenses in multiple dimensions (2D or 3D arrangements). This dimensional expansion allows creation of multiple optical traps simultaneously in different spatial locations, achieving both miniaturization and efficient trapping

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Quantity of substance

If arrays of VECSELs are used to generate multiple optical traps, then trap array size is improved, but manufacturing difficulty and cost increase

Engineering Contradiction:
Improvenumber of trapsVSAvoidfabrication yield
Core Design Contradiction:
Quantity of substanceVSEase of manufacture

Solution Approach 1:

The patent merges multiple laser sources into a single laser that illuminates an entire array of micro-lenses. This combining approach replaces the need for multiple independent VECSELs with one laser source, dramatically simplifying manufacturing while still generating large arrays of optical traps through the micro-lens array

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent uses a single laser beam that is copied and distributed across multiple micro-lenses in the array. Each micro-lens creates a focal point that is essentially a copy of the original beam's trapping capability, enabling generation of many traps from one source

Inventive Principle:
Principle #26Copying

3Adaptability or versatility

If diffractive optical elements are used to create trap arrays, then trap array configuration is improved, but trapping efficiency decreases due to ghost images and diffraction orders

Engineering Contradiction:
Improvetrap configurationVSAvoidtrapping efficiency
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent extracts the trap configuration function from the optical element itself and separates it into two components: micro-lenses that provide efficient focal points without ghost images, and spatial light modulators or movable stages that independently control trap positions. This extraction eliminates the ghost image problem inherent in diffractive elements while maintaining configuration flexibility

Inventive Principle:
Principle #2Taking out (Extraction)

4Ease of operation

If spatial light modulators are used for trap addressing, then individual trap control is improved, but response speed decreases

Engineering Contradiction:
Improvetrap addressingVSAvoidresponse time
Core Design Contradiction:
Ease of operationVSSpeed

Solution Approach 1:

The patent replaces the liquid crystal-based spatial light modulator with a mechanically controlled system using movable stages or piezoelectric actuators that physically reposition the micro-lens array or the sample stage. This mechanical substitution eliminates the slow response time of liquid crystals while maintaining individual trap addressing capability through precise positional control

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

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 the creation of compact, scalable 3D optical trap arrays that can handle high numbers of particles with improved trapping efficiency and flexibility, suitable for bio-chip technologies, and allows for parallel processing and real-time manipulation.

Implementation Method 1

Momentum transfer between light and dielectric matter allows manipulation of micron-sized particles immersed in a fluid media whose refractive index is different than that of the particle

Methodology Applied
Scientific EffectOptical trapping: Optical Tweezers

Implementation Method 2

A highly focused laser beam allows three dimensional trapping of particles

Methodology Applied
Scientific EffectLight focusing: Focusing

Implementation Method 3

an array of micro-mirrors to counterbalance scattering forces, allowing for efficient 3-dimensional optical trapping

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP1934645B1Miniaturized optical tweezer array with an array of reflective elements for reflecting the light back to a focal area
Publication Date: 2011.08.17 ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE (EPFL)
  • EP1934645B1 patent drawingFigure 1
  • EP1934645B1 patent drawingFigure 2
  • EP1934645B1 patent drawingFigure 3

AI summary

Apparatus for forming a single or a plurality of threedimensional optical traps, the apparatus comprising: a. A collimated light source that is directed onto an array of focalizing refractive or diffractive elements providing a single or a plurality of focal areas, and b. An array of reflective elements, placed opposite to the said focalizing elements described in a), which reflect back the light into the said focal area. The invention also relates to a method for using this apparatus.