Microdroplet Loading via Pressure and Electrowetting Pathways
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Solution Overview
Problem
Existing electrowetting-on-dielectric (EWOD) and optoelectrowetting (oEWOD) devices face limitations in processing large numbers of microdroplets due to constraints on parallel processing capacity and inefficient loading methods, which hinder high-throughput manipulation and separation of droplets in pharmaceutical applications.
Innovation Solution
A device comprising a chip with a channel system that allows microdroplets to flow from a reservoir into a manipulation region at a controlled velocity, using a pressure source and fluted or blunted channel ends to slow droplets for efficient loading and separation, along with electrowetting pathways for precise control and sieving effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If microdroplets are loaded at high velocity to increase throughput, then productivity is improved, but manufacturing precision deteriorates due to inability to control droplet placement
Solution Approach 1:
The loading process is divided into two distinct phases: a high-velocity loading phase where droplets are rapidly introduced onto the chip, and a low-velocity manipulation phase where droplets are precisely positioned using electrowetting forces. This segmentation allows the system to achieve both high throughput and precise placement by optimizing each phase independently.
Solution Approach 2:
Droplets are pre-loaded onto the chip at high velocity without immediate manipulation, allowing rapid population of the chip surface. The precise positioning and manipulation actions are then applied subsequently using electrowetting forces, separating the loading function from the positioning function to maximize both speed and precision.
2Productivity
If large numbers of droplets are processed in parallel to increase throughput, then productivity is improved, but device complexity increases due to optical manipulation constraints
Solution Approach 1:
The patent replaces complex optical manipulation systems with electrowetting-based actuation. Instead of using multiple optical focuses to manipulate individual droplets, the system uses electrical fields applied through pixelated electrodes to control droplet movement, merging, and positioning. This substitution dramatically reduces device complexity while enabling processing of millions of droplets in parallel.
Solution Approach 2:
The system changes the control parameter from optical focusing to electrical voltage application. By varying the voltage applied to different electrode pixels, the system can selectively manipulate droplets across the entire chip surface simultaneously, achieving high parallel processing capacity without the complexity of optical systems.
3Ease of operation
If batch loading processes are used to load droplets, then ease of operation is improved, but loss of time increases due to process switching
Solution Approach 1:
The electrowetting-based loading system enables continuous operation without batch processing interruptions. Droplets are continuously introduced and manipulated in real-time using electrical fields, eliminating the need to stop and restart processes. This continuous action maintains ease of operation while eliminating time losses associated with batch process switching.
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
Enables the efficient loading and manipulation of millions of microdroplets, optimizing space usage and allowing for rapid identification and removal of undesired droplets, thereby enhancing the throughput and yield of desired droplets in EWOD or oEWOD systems.
Implementation Method 1
a pressure source for moving the microdroplets from the microdroplet source along the channel and into the first region of the chip
Implementation Method 2
the distal end of the channel is fluted or blunted such that the microdroplets move from the distal end of the channel into the first region of the chip at a velocity which is lower than the first velocity
Implementation Method 3
Electrowetting-on-dielectric (EWOD) is a well-known effect in which an electric field applied between a liquid and a substrate makes the liquid more wetting on the surface than the natural state
Implementation Method 4
At least one of the containing walls includes what are hereinafter referred to as 'virtual' electrowetting electrode locations which are generated by selectively illuminating an area of a semiconductor layer buried within
Data Source
AI summary
A device for manipulating many hundreds or thousands of microdroplets into an array using EWOD or oEWOD is provided. The device comprises: i) a chip comprising a first region for receiving and manipulating microdroplets; a second region comprising the array and a plurality of electrowetting pathways leading to the array; ii) a microdroplet source configured to provide microdroplets of a predetermined target diameter; iii) a channel configured to provide fluid communication between the microdroplet source and the first region of the chip; and iv) a pressure source configured to move the microdroplets between the microdroplet source and the first region of the chip. The electrowetting pathways on the chip are centre to centre separated by at least double the predetermined target diameter of the microdroplets from the microdroplet source. Furthermore, the controller is configured to enable synchronous movement of the microdroplets in the electrowetting pathways by application of EWOD or oEWOD force.