Combed Spacer for Side-Loaded EWOD Fluid Control
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Solution Overview
Problem
Current side loading designs for EWOD devices face challenges in controlling the input of polar fluids, particularly when using an incomplete oil filling method, leading to inefficient and uncontrolled fluid loading, with issues such as air bubbles forming at incorrect locations and polar fluids becoming stranded away from the EWOD channel.
Innovation Solution
An enhanced spacer configuration with combed teeth extending into the EWOD channel, defining fluid input ports that ensure polar fluids make contact with nonpolar oil, allowing for controlled side loading by directing fluids into the channel and preventing mixing or stranding, thus facilitating efficient fluid input and output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If side loading is used for fluid input, then device complexity is reduced and manufacturing cost decreases, but fluid input control becomes uncontrolled and unreliable
Solution Approach 1:
The spacer is segmented into multiple teeth structures that extend into the EWOD channel, creating discrete fluid input ports between adjacent teeth. This segmentation allows controlled fluid input at multiple locations while maintaining the simplicity of side loading, resolving the contradiction between ease of manufacture and fluid input control reliability.
Solution Approach 2:
The spacer teeth act as intermediary structures that mediate between the external fluid source and the EWOD channel. These teeth create defined pathways and barriers that control fluid entry, ensuring reliable fluid input control while maintaining the simplified side loading approach.
2Ease of manufacture
If incomplete oil filling method is used, then device assembly is simplified, but air bubbles form at incorrect locations and polar fluids become stranded
Solution Approach 1:
The spacer teeth are pre-configured to create defined fluid input ports and pathways before fluid loading occurs. This preliminary structural arrangement ensures that when incomplete oil filling is used, air bubbles form at predetermined locations and polar fluids are guided to correct positions, preventing stranding and improving manufacturing precision.
Solution Approach 2:
The spacer teeth create localized regions with different fluid dynamics characteristics. The spaces between teeth provide controlled entry points for polar fluids, while the teeth themselves act as barriers that prevent fluid stranding. This local differentiation of fluid control quality resolves the contradiction between simplified assembly and precise fluid positioning.
3Productivity
If multiple fluid input ports are created in upper substrate, then fluid loading capability increases, but substrate complexity and manufacturing difficulty increase
Solution Approach 1:
The spacer structure is combined with the substrate to create fluid input ports, merging the functions of structural support and fluid control into a single component. This eliminates the need for separate holes in the upper substrate while maintaining multiple fluid loading capability, reducing device complexity while preserving productivity.
Solution Approach 2:
Instead of creating multiple holes in the two-dimensional substrate plane, the fluid input ports are created by extending the spacer structure into the third dimension (vertical height) of the device. The teeth extend downward into the EWOD channel, creating multiple access points without increasing substrate planar complexity.
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
The enhanced spacer configuration ensures reliable and controlled fluid input into the EWOD channel, reducing manufacturing costs and increasing the density of fluid entry points, while maintaining the structural integrity of the device, and allows for efficient extraction of processed fluids.
Implementation Method 1
the spacer is configured for directing fluid from the fluid input ports into the channel
Implementation Method 2
The function of the oil is to reduce the surface tension at the surfaces of the polar droplets, and to increase the electro-wetting force
Implementation Method 3
Electrowetting on dielectric (EWOD) is a well-known technique for manipulating droplets of fluid by the application of an electric field
Data Source
AI summary
An EWOD device includes a first and second substrate assemblies, and a spacer that spaces apart the first substrate assembly from the second substrate assembly to define a channel between them. The spacer defines fluid input ports that are in fluid communication with the channel, and the spacer is configured for directing fluid from the fluid input ports into the channel. The spacer has a combed spacer configuration to define the fluid input ports, including alternating teeth that extend into the channel from a base region, and the teeth isolate adjacent fluid input ports from each other. The spacer may contact only a portion of the first and second substrate assemblies to form a spacerless region within the EWOD device, and the spacer includes regions that are in contact with both the first and second substrate assemblies and extend into the channel to define a cell-gap of the channel.