Nanoporous Membrane Fabrication via Liquid Metal Ion Beam

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Solution Overview

Problem

The challenge lies in the simple, economical, and reproducible manufacture of nano-porous membranes with variable characteristics, such as size and material, to meet the increasing demand, while existing methods face issues with reproducibility and mechanical/chemical contamination.

Innovation Solution

A method using an ion beam generator with a liquid metal ion source, where the ion beam is focused and controlled to create and plug pores in membranes with adjustable diameters, employing a charged particle detector and electrostatic optics to manage the ion beam's intensity and area of impact, ensuring precise control over pore formation and filling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an erosion mechanism is used to seal pores, then pore sealing is achieved, but mechanical damage and chemical contamination increase significantly

Engineering Contradiction:
Improvepore sealing effectivenessVSAvoidmechanical damage and chemical contamination
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical erosion-based sealing mechanism with a chemical deposition mechanism. Instead of physically eroding material to seal pores, the invention uses ion beam-induced deposition of material onto the pore walls, transforming the sealing process from a mechanical to a chemical/physical deposition process that avoids mechanical damage.

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

Solution Approach 2:

The patent converts the potentially harmful ion beam, which can cause damage through erosion, into a beneficial tool for deposition. By controlling the ion beam parameters and using it in deposition mode rather than erosion mode, the harmful erosive effect is transformed into a useful depositional effect that seals pores without mechanical damage.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

2Adaptability or versatility

If variable pore characteristics are implemented, then adaptability increases, but manufacturing complexity increases

Engineering Contradiction:
Improvevariable pore characteristicsVSAvoidmanufacturing process complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent achieves variable pore characteristics by changing ion beam parameters (energy, current, duration, scanning patterns) rather than changing the physical manufacturing setup. This allows different pore sizes, shapes, and distributions to be created using the same equipment by simply adjusting beam parameters, maintaining manufacturing simplicity while achieving high adaptability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses dynamic control of the ion beam scanning patterns and exposure times to create different pore configurations. The beam can be dynamically steered and modulated to produce various pore characteristics on demand, allowing a single static manufacturing system to produce dynamically variable results.

Inventive Principle:
Principle #15Dynamics

3Manufacturing precision

If high precision pore formation is achieved, then manufacturing precision improves, but process time increases

Engineering Contradiction:
Improvepore formation precisionVSAvoidprocess time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent uses periodic pulsed ion beam exposure rather than continuous exposure. The beam is applied in controlled pulses with specific durations and intervals, allowing precise material removal or deposition while minimizing total process time. This periodic action enables high precision by controlling the cumulative dose while reducing overall exposure time compared to continuous low-intensity irradiation.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent performs preliminary focusing and positioning of the ion beam before the actual pore formation process. By pre-positioning the beam with high accuracy and pre-setting the scanning patterns, the actual processing time is minimized while maintaining high precision. The preliminary setup ensures that subsequent processing is both fast and precise.

Inventive Principle:
Principle #10Preliminary action

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 allows for the controlled creation and plugging of pores with high precision, reducing mechanical damage and contamination, and enabling the production of membranes with desired properties, improving reproducibility and adaptability.

Implementation Method 1

a beam-forming device adapted to emit a beam of charged species along an optical axis towards a sample holder carrying a membrane opposite the source along the optical axis

Methodology Applied
Scientific EffectIon beam etching: Ion Beam

Implementation Method 2

In drilling mode, as long as a number of ions is detected below a predetermined threshold, the generator delivers a beam of charged species onto an area of the membrane

Methodology Applied
Scientific EffectSputtering: Sputtering

Implementation Method 3

a charged particle detector being provided downstream of the membrane along the optical axis, the particle detector being adapted to detect a number of ions transmitted through the membrane

Methodology Applied
Scientific EffectIon detection: Ionisation

Implementation Method 4

a target pore diameter is defined, and the drilling and sealing modes are alternated until a pore of said diameter is formed

Methodology Applied
Scientific EffectElectrostatic lensing: Electrostatic Lens

Implementation Method 5

the ion beam is focused at the sample holder into an area of adjustable diameter

Methodology Applied
Scientific EffectElectrostatic deflection: Electrostatics

Data Source

PatentEP2877273B1Method and apparatus for forming a nanoporous membrane
Publication Date: 2022.10.26 CENT NAT DE LA RECH SCI (C N R S)
  • EP2877273B1 patent drawingFigure 1
  • EP2877273B1 patent drawingFigure 2a~7
  • EP2877273B1 patent drawingFigure 4~5b

AI summary

An ion beam generator (100) is supplied with liquid metal, emitting a beam of charged particles along an axis. A sample carrier (4) is provided bearing a membrane facing the source along the axis. A particle detector (15) is provided. The ion beam is controlled according to the number of ions detected.