EWOD Droplet Control With Intermittent Actuation Patterns

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Solution Overview

Problem

Excessive or prolonged actuation of EWOD or AM-EWOD elements can damage droplets and device components due to electric fields, affecting delicate reagents and reducing device lifetime.

Innovation Solution

Implementing a control system that uses intermittent actuation patterns to minimize the time EWOD elements are actuated, thereby reducing exposure to electric fields and minimizing damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If continuous actuation is used to maintain droplet operations, then droplet manipulation reliability is improved, but device lifetime deteriorates due to electric field damage

Engineering Contradiction:

Improvedroplet manipulation reliabilityVSAvoiddevice lifetime

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent applies periodic action by implementing intermittent actuation patterns where EWOD elements are activated only during necessary operations rather than continuously. The control system monitors droplet state and triggers actuation only when needed, creating periodic on/off cycles that maintain operational reliability while reducing cumulative electric field exposure and extending device lifetime.

Inventive Principle:

Principle #19Periodic action

2Stability of the object's composition

If prolonged actuation is applied to ensure droplet operation stability, then droplet position control is improved, but droplet damage increases due to electric field exposure

Engineering Contradiction:

Improvedroplet position stabilityVSAvoiddroplet damage from electric fields

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The patent implements feedback control by continuously monitoring droplet state (position, shape, size) and using this information to determine when actuation is necessary. The control system adjusts actuation timing based on real-time droplet state, applying electric fields only when droplet stability requires correction, thereby maintaining position stability while minimizing harmful electric field exposure.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system uses periodic monitoring and intermittent actuation, triggering EWOD element activation only when droplet state deviations exceed thresholds. This creates selective periodic action rather than continuous actuation, maintaining droplet stability when needed while reducing cumulative electric field damage.

Inventive Principle:

Principle #19Periodic action

3Manufacturing precision

If frequent actuation is used to maintain precise droplet control, then droplet operation precision is improved, but reagent damage increases due to excessive electric field exposure

Engineering Contradiction:

Improvedroplet operation precisionVSAvoidreagent damage from electric fields

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The control system uses feedback from droplet state monitoring to determine precise when actuation is needed, avoiding unnecessary frequent actuation. By triggering EWOD elements only when droplet position, shape, or size deviations occur, the system maintains operational precision while minimizing electric field exposure that could damage delicate reagents.

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 approach effectively performs droplet operations while reducing the risk of damage to droplets and device components, enhancing device reliability and preventing harm to fragile reagents.

Implementation Method 1

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

Methodology Applied

Scientific EffectElectrowetting: Electrowetting

Implementation Method 2

The resulting electrical forces that are set up effectively control the hydrophobicity of the hydrophobic coating 24

Methodology Applied

Scientific EffectElectric field: Electric Field

Data Source

PatentEP3381557B1Am-EWOD device and control methods with intermittent actuation patterns

Publication Date: 2025.05.07 SHARP LIFE SCI EU LTD

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AI summary

A microfluidic system includes an electro-wetting on dielectric (EWOD) device and a control system that controls actuation voltages applied to the element array of the EWOD device to perform manipulation operations as to fluid droplets. The control system applies a sequence of actuation voltages to a portion of the array elements associated with a droplet to maintain the droplet in a desired droplet state corresponding to a predetermined droplet property. The sequence of actuation voltages includes an actuation-on period in which the portion of the array elements associated with the droplet is actuated and an actuation-off period in which the portion of the array elements associated with the droplet is not actuated, and the actuation-off period is non-zero. The control system may apply a sequence of actuation voltages comprising a predetermined duty cycle, and/or the actuation voltages may be applied in accordance with a sensor based intervention.