In-Plane Reference Electrode for AM-EWOD Cross-Talk Reduction
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Solution Overview
Problem
The actuation of liquid droplets in Active Matrix Electro-wetting-On-Dielectric (AM-EWOD) devices requires high voltage switching, and the sensor performance is inadequate due to insufficient voltage minimization and cross-talk between array elements.
Innovation Solution
An AM-EWOD device with an in-plane reference electrode configuration, where the reference electrode is disposed on the same substrate as the array element electrodes, allowing for separate voltage waveforms for actuation and sensing operations, minimizing voltage switching and using the reference electrode as an electromagnetic shield to reduce cross-talk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high voltage switching is used for actuation of liquid droplets, then droplet actuation is enabled, but voltage requirements are excessive and sensor performance deteriorates due to cross-talk
Solution Approach 1:
The patent segments the voltage control by providing separate voltage waveforms for actuation and sensing operations. The reference electrode receives a first voltage waveform during actuation and a second voltage waveform during sensing, allowing independent optimization of each function and minimizing interference between them.
Solution Approach 2:
The reference electrode acts as an intermediary element that, when disposed in-plane with the array element electrodes, serves as an electromagnetic shield during sensing operations. This shielding configuration reduces parasitic interactions and cross-talk between neighboring array elements while maintaining actuation functionality.
2Ease of operation
If conventional EWOD configuration is used, then droplet manipulation is achieved, but voltage switching requirements are high
Solution Approach 1:
The patent implements dynamic voltage waveform control where the reference electrode voltage is changed based on operational mode. During actuation, a first voltage waveform is applied, and during sensing, a second voltage waveform is applied, allowing the system to adapt voltage requirements dynamically and minimize energy consumption for voltage switching.
Solution Approach 2:
The patent changes the voltage parameter of the reference electrode based on operational requirements. By switching between different voltage waveforms (different amplitude, frequency, or phase characteristics) for actuation versus sensing modes, the system optimizes performance while reducing excessive voltage requirements.
3Measurement precision
If sensor operations are performed with actuation voltages applied, then droplet sensing is enabled, but sensor performance is insufficient due to parasitic interactions
Solution Approach 1:
The in-plane disposed reference electrode serves as an electromagnetic shield during sensing operations, intercepting and redirecting electromagnetic fields that would otherwise create parasitic interactions between neighboring array elements. This shielding effect isolates the sensing measurement from harmful electromagnetic interference.
Solution Approach 2:
The patent employs periodic switching between actuation and sensing modes with corresponding voltage waveforms. During sensing periods, the reference electrode is configured to minimize parasitic interactions, allowing accurate measurements to be taken periodically without continuous interference from actuation voltages.
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 configuration enables efficient actuation of liquid droplets with minimized voltage requirements and improved sensor performance by reducing parasitic interactions between neighboring array elements.
Implementation Method 1
using the reference electrode as an electromagnetic shield to reduce cross-talk
Implementation Method 2
Electro-wetting on dielectric (EWOD) is a well known technique for manipulating droplets of fluid by application of an electric field
Data Source
AI summary
An AM-EWOD device comprises: first and second substrates (72,36); first and second array element electrodes (38A, 38B) disposed on the first substrate (72) and defining first and second array elements in the AM-EWOD device; a reference electrode (28) disposed on the first substrate (72); a sensor; and a reference electrode drive circuit (50). The reference electrode drive circuit (50) is configured to drive the reference electrode with a first voltage waveform for actuating an array element or with a second voltage waveform different from the first voltage waveform when performing a sensing operation.