EWOD Fluid Loading Holdback Port for Precise Droplet Input
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional EWOD devices face challenges in efficiently controlling the input and output of fluids, leading to overfilling and reduced throughput due to the lack of precise control over fluid loading and extraction, which is not adequately addressed by existing mechanisms.
Innovation Solution
The implementation of a controlled and automated fluid input and extraction system using a seal mechanism in EWOD devices, where fluid is held back in a dedicated well and input into the channel only when needed, allowing for precise control through the manipulation of the seal and electrowetting forces, enabling efficient handling of multiple droplet manipulation operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional fluid input mechanisms are used in EWOD devices, then fluid can be input into the channel, but fluid overfilling occurs and throughput is reduced due to lack of precise control
Solution Approach 1:
The patent introduces a control port with a seal as an intermediary component between the fluid reservoir and the EWOD channel. This seal acts as a mediator that precisely regulates fluid transfer, allowing controlled dispensing of droplets while preventing overfilling. The control port mechanism enables exact fluid metering, directly resolving the contradiction between maintaining high throughput and achieving precise fluid loading control.
2Reliability
If fluid is continuously supplied to the EWOD channel, then the channel remains filled, but dead volume increases and fluid resources are wasted
Solution Approach 1:
The patent implements preliminary action by pre-filling the reservoir with fluid before the EWOD device is activated. The control port remains sealed during storage and transport, maintaining fluid readiness without continuous supply. This approach ensures the channel can be quickly filled when needed while minimizing dead volume and preventing fluid waste during idle periods, thus resolving the contradiction between maintaining fluid availability and reducing fluid loss.
3Manufacturing precision
If a seal mechanism is added to control fluid input, then precise fluid control is achieved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the fluid input system into distinct functional components: a reservoir, a control port with seal, and the EWOD channel. This modular segmentation allows the seal mechanism to be integrated as a discrete element that provides precise control without requiring complex overall device redesign. The segmented architecture enables precise fluid input control while managing device complexity through functional modularity.
4Quantity of substance
If the control port is sealed during fluid holding, then fluid is restricted from entering, but activation volume increases due to additional sealing requirements
Solution Approach 1:
The patent implements self-service by designing the control port seal to be automatically activated and deactivated based on the operational state of the device. The seal engages naturally when the device is in fluid holding mode and disengages when fluid input is required, eliminating the need for additional actuation mechanisms. This self-regulating seal design ensures precise fluid holding control while minimizing activation volume requirements.
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 enhances the efficiency of fluid handling, reduces overfilling, and maintains high throughput by allowing for controlled and reproducible fluid input and output, minimizing the 'dead volume' and activation volume required, thus optimizing the use of fluid resources.
Implementation Method 1
excess oil fills the fluid input wells of the input ports and is held back within the vent hole in the top substrate due to surface tension
Implementation Method 2
voltages termed the EW drive voltages, (e.g. V T , V 0 and V 00 in Fig. 1) may be externally applied to different electrodes (e.g. reference electrode 30, element electrodes 12, 12A and 12B, respectively). The resulting electrical forces that are set up effectively control the hydrophobicity of the hydrophobic coating 24
Implementation Method 3
vent hole also may be provided through the top substrate assembly for the elimination of air from the EWOD channel
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An electrowetting on dielectric (EWOD) device includes a first substrate assembly and a second substrate assembly spaced apart to define a channel between them; an input port in fluid communication with the channel, the input port defining an input well for receiving a fluid for inputting into the channel; and a control port in fluid communication with the channel, the control port defining a control well for receiving a fluid and having a seal that seals the control port in a sealed state in which fluid is restricted from entering the control well from the channel. When the seal is pierced, the control port is placed in an unsealed state permitting fluid to enter the control well from the channel. The electrowetting force may be manipulated to remove the dispensed droplets via an exit port. Multiple cycles of fluid input/droplet manipulation/fluid extraction may be repeated to perform complex reaction protocols.