Microfluidic Flow Sorting Via Localized Sheath-Fluid Heating

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Solution Overview

Problem

Current microfluidic devices are limited in their ability to sort nano-objects at high speeds without damaging their integrity or viability, and they require excessive dilution and encapsulation steps that are not compatible with biological and medical applications.

Innovation Solution

A microfluidic device with sheath fluid inlet channels and a common channel that uses localized heating by photo-thermal or electro-thermal transducers to modify the viscosity of sheath fluid, allowing precise deflection of sample fluid towards specific outlet channels at high switching frequencies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If traditional flow cytometers are used to detect and sort nano-objects, then detection and sorting capability is provided, but the sorting rate is limited to below 1 kHz and the objects must be larger than 100 nm

Engineering Contradiction:

Improvesorting rateVSAvoidobject size detection limit

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent replaces mechanical sorting methods with optical manipulation using optical tweezers. A focused laser beam creates gradient forces that trap and manipulate individual nano-objects in a fluid stream, enabling high-speed sorting of objects below 100 nm without mechanical contact or large drop encapsulation

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the detection and manipulation parameters by using optical fields instead of mechanical fields. The optical tweezers can detect and sort nano-objects based on their optical properties (scattering, absorption) rather than requiring them to be larger than a certain size, achieving both high sorting rates and nanometric detection capability

Inventive Principle:

Principle #35Parameter changes

2Productivity

If micromechanical techniques with valves are used to sort cells, then sorting capability is provided, but the sorting rate does not exceed 1 Hz

Engineering Contradiction:

Improvesorting rateVSAvoidvalve mechanism complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent replaces complex micromechanical valve systems with a simple optical trap. The optical tweezers can rapidly redirect trapped nano-objects into different collection channels by moving the laser beam or adjusting trap position, achieving kHz sorting rates without mechanical moving parts

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an optical field as an intermediary between the fluid stream and the sorting mechanism. The optical tweezers act as a non-contact mediator that can rapidly transfer nano-objects between different spatial locations and collection channels, enabling high-speed sorting without mechanical valves

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If dielectrophoresis or surface acoustic waves are used for sorting, then sorting rate of kHz is achieved, but preformed micrometric drops encapsulating individual objects are required

Engineering Contradiction:

Improvesorting rateVSAvoidencapsulation process complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent replaces the need for micrometric drop encapsulation with direct optical manipulation of individual nano-objects in a continuous fluid stream. The optical tweezers can selectively trap and sort objects without requiring them to be encapsulated in drops, simplifying the overall process while maintaining kHz sorting rates

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Productivity

If cavitation is used to laterally move particles at 10 kHz switching frequency, then high switching frequency is achieved, but the integrity of nano-objects or viability of biological objects is damaged

Engineering Contradiction:

Improveswitching frequencyVSAvoiddamage to nano-objects and biological cells

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the potential harm of intense laser fields into a beneficial effect by using optical tweezers. The same laser technology that could cause cavitation and damage is instead used at controlled intensities to create gentle gradient forces that trap and manipulate objects without contact, achieving high switching frequencies while preserving object integrity and biological viability

Inventive Principle:

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

Data Source

PatentUS20250325979A1Microfluidic device, system and method for manipulating a flowing fluid

Publication Date: 2025.10.23 HEKAT

AI summary

The invention relates to a microfluidic device (100) comprising at least one sheath fluid inlet channel (1, 2) and a sample fluid inlet channel (3), and a common channel (4) configured to guide the sample fluid (20), with hydrodynamic focusing, and the at least one sheath fluid (21, 22) in the direction of at least two outlet channels (11, 12, 13).According to the invention, the microfluidic device comprises heating means arranged to transmit over a short period of time an amount of heat localised in the at least one sheath fluid flow (21, 22) in the common channel (4) upstream of a junction between the at least two outlet channels (11, 12, 13) and the at least one sheath fluid having a thermal variation in viscosity suitable for diverting or extracting a portion (120, 130, 220) of the sample fluid selectively towards a given outlet channel.