EWOD Droplet Diffusion Separation for Microfluidic Sizing

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Solution Overview

Problem

Conventional microfluidic systems for diffusion separation are bulky and require large amounts of sample and buffer fluids, making them inefficient compared to Active Matrix Electrowetting-On-Dielectric (AM-EWOD) devices.

Innovation Solution

The use of an EWOD or AM-EWOD device to perform droplet-based microfluidic diffusion sizing and separation by forming sample and collection droplets, merging them to enable particle diffusion, and then separating the droplets to fractionate particles, using electrowetting forces to minimize bulk disturbance and convective mixing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If conventional microfluidic systems are used for diffusion separation, then separation can be achieved, but the systems become bulky and require large amounts of sample and buffer fluids

Engineering Contradiction:

Improveamount of sample and buffer fluidsVSAvoidsystem size

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The invention segments the continuous fluid system into discrete droplets that can be individually manipulated on the EWOD device. By dividing the sample and buffer into separate droplets that can be precisely controlled and merged only when needed, the system achieves separation functionality while dramatically reducing the total volume of fluids required compared to conventional continuous flow systems.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention replaces the mechanical continuous flow system with an electrowetting-based droplet manipulation system. Instead of using pumps and channels to continuously flow large volumes of fluid, the system uses electrical fields to control discrete droplets, enabling precise control with minimal fluid volumes and eliminating the need for bulky mechanical components.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Stability of the object's composition

If electrowetting forces are used to control droplets, then bulk disturbance and convective mixing are minimized, but precise control of droplet merging is required

Engineering Contradiction:

Improvedroplet composition stabilityVSAvoiddroplet merging control

Core Design Contradiction:

Stability of the object's compositionVSEase of operation

Solution Approach 1:

The invention uses optical detection (analogous to color changes) to monitor droplet positions and merging events in real-time. Sensors detect the presence and position of droplets, providing feedback that enables precise control of the electrowetting operations, ensuring droplets merge only when intended while maintaining composition stability during transport.

Inventive Principle:

Principle #32Color changes

Solution Approach 2:

The system incorporates sensors that detect droplet positions and provide feedback to the control system. This feedback mechanism allows the system to adjust electrowetting voltages in real-time, ensuring precise control of droplet merging while maintaining droplet stability during transport, thus resolving the contradiction between stability and ease of operation.

Inventive Principle:

Principle #23Feedback

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 method achieves efficient particle separation using less buffer and sample materials than conventional systems, allowing for more precise and cost-effective microfluidic diffusion separation.

Implementation Method 1

Electrowetting on dielectric (EWOD) is a well-known technique for manipulating droplets of fluid by application of an electric field

Methodology Applied

Scientific EffectElectrowetting: Electrowetting

Implementation Method 2

at an initial time, initiating a process of particle separation by which a portion of the sample droplet is introduced into the collection droplet, wherein the first particles move through the collection droplet at a rate different from the second particles

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS11219898B2Molecular separation by diffusion using an EWOD device

Publication Date: 2022.01.11 SHARP LIFE SCI EU LTD

AI summary

A method of operating an electrowetting on dielectric (EWOD) device performs microfluidic diffusion separation. The method includes the steps of: inputting a sample droplet into the EWOD device, wherein the sample droplet includes a mixture of particles including first particles and second particles that are different from each other; inputting a collection droplet into the EWOD device; performing an electrowetting operation to bring the sample droplet into contact with the collection droplet; at an initial time, initiating a process of particle separation by which a portion of the sample droplet is introduced into the collection droplet, wherein the first particles move through the collection droplet at a rate different from the second particles; and after a time interval from the initial time, performing an electrowetting operation to segment a leaving droplet from the collection droplet, wherein the leaving droplet has a higher concentration of the first particles relative to the second particles as compared to a concentration of the first particles relative to the second particles in the sample droplet at the initial time. The method may be performed by an AM-EWOD control system executing program code stored on a non-transitory computer readable medium.