Microfluidic Pump with Variable Oxidation State Electrodes
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Solution Overview
Problem
Existing microfluidic pumps based on electrowetting require high voltages, making integration with standard IC technologies impossible, as they are not compatible with state-of-the-art IC fabrication processes.
Innovation Solution
A microfluidic pump system utilizing metal electrodes that oxidize in air, where the oxidation state of the electrodes is controlled to vary wettability, allowing for lower voltage operation and integration with semiconductor devices, using a substrate with dielectric layers and wells for electrode placement, and a counter electrode for liquid movement control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrowetting systems use high voltage (40V-80V) to control droplet movement, then droplet motion control is achieved, but integration with standard IC technologies becomes impossible
Solution Approach 1:
The patent changes the operating voltage parameter from high voltage (40V-80V) to low voltage by utilizing the oxidation-reduction property of metal electrodes. The metal electrodes naturally oxidize in air to form oxide layers that provide the necessary wettability control without requiring high external voltages, thus enabling compatibility with standard IC technologies while maintaining reliable droplet motion control
Solution Approach 2:
The metal electrodes perform self-service by naturally oxidizing in air to form the required oxide surface. This self-oxidation process eliminates the need for external high voltage applications or complex dielectric layers, simplifying the device structure and enabling direct integration with IC technologies while maintaining effective wettability control for droplet manipulation
2Reliability
If a dielectric layer is used to separate the electrode metal from the liquid to prevent electrolysis, then electrolysis is prevented, but the device size increases and integration becomes more difficult
Solution Approach 1:
The patent extracts and removes the dielectric layer from the system by utilizing metal electrodes that naturally form protective oxide surfaces through air oxidation. This eliminates the need for separate dielectric layers while maintaining electrolysis prevention, thereby reducing device size and simplifying the overall structure for better integration
Solution Approach 2:
The metal oxide surface acts as an intermediary between the metal electrode and the liquid. The oxide layer provides the necessary barrier function to prevent electrolysis while allowing the system to operate at low voltages, effectively replacing the traditional dielectric layer and reducing device complexity and size
3Use of energy by moving object
If metal electrodes with variable oxidation states are used to control wettability, then lower voltage operation is achieved, but control mechanisms become more complex
Solution Approach 1:
The metal electrodes utilize their inherent property of oxidizing in air to control wettability. By simply exposing the metal electrodes to air, they naturally form oxide surfaces that provide the desired wettability characteristics, eliminating the need for complex external control mechanisms while achieving low voltage operation
Solution Approach 2:
The metal electrodes are pre-treated by exposure to air during fabrication or operation to establish the oxide surface before liquid contact. This preliminary oxidation action prepares the surface with the required wettability properties, simplifying subsequent operation and reducing the complexity of real-time control mechanisms
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 creation of smaller, more integrated microfluidic devices that can be fabricated using standard semiconductor processes, allowing for lower voltage operation and compatibility with IC technologies, facilitating the use of microfluidic pumps in biosensors and ISFETs with reduced device size and voltage requirements.
Implementation Method 1
a plurality of metal electrodes which oxidise in air
Implementation Method 2
A liquid that touches a surface will spread along this surface by an amount which depends on its wettability on this surface
Implementation Method 3
Many different microfluidic pumps have been proposed which operate based on the principle of electrowetting
Data Source
AI summary
A microfluidic pump comprises a plurality of metal electrodes (10) which oxidise in air, a liquid droplet (14) to be moved by the pump, which is in contact with a least one metal electrode, and a controller for controlling the oxidation state of the metal electrodes in order to vary the electrode wettability. This arrangement enables full integration with a semiconductor device, and with low drive voltages.