Bubble-Driven Micropump Using Electrolysis and Venting Membranes
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Solution Overview
Problem
Current bubble-driven micropumps are energy-intensive due to heat loss and lack a suitable mechanism for directional liquid pumping in closed-loop microfluidic devices, particularly in fuel cells, where bubble generation methods other than boiling are difficult to implement and inefficient.
Innovation Solution
A method and device utilizing directional growth and elimination of gaseous vesicles (bubbles) within a fluid-containing passageway, employing asymmetric channel structures and venting membranes to control bubble flow, allowing for the use of various bubble generation schemes like electrolysis, heating, or chemical reactions, enabling directional fluid pumping without condensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If thermal generation (boiling) is used to form bubbles, then bubble-driven pumping can be achieved, but energy consumption increases due to high heat loss in microscale environment
Solution Approach 1:
The patent changes the physical mechanism from thermal phase change to electrochemical gas generation. By using electrolysis to generate gas bubbles directly in the liquid phase without heating, the system eliminates the high heat loss associated with thermal generation in microscale environments, thereby improving energy efficiency
Solution Approach 2:
The patent replaces the thermal field (heating/boiling) with an electrochemical field (electrolysis). This substitution eliminates the need for thermal energy input and the associated heat loss, using electrical energy to directly generate gas bubbles for pumping
2Reliability
If conventional micromechanical pumps are used, then reliable liquid transport can be achieved, but device complexity increases due to moving valves and mechanical components
Solution Approach 1:
The patent extracts and eliminates the mechanical valve components from the pumping system. By using electrochemically generated gas bubbles to drive liquid flow through pressure differentials, the system achieves reliable pumping without moving parts, valves, or complex mechanical mechanisms
Solution Approach 2:
The patent implements a self-regulating pumping mechanism where electrochemical reactions automatically generate gas bubbles that create the necessary pressure differentials. The system uses the electrochemical energy input to directly create the driving force, eliminating the need for external mechanical control components
3Use of energy by moving object
If bubble generation methods other than boiling are used, then energy efficiency can be improved, but bubble removal becomes difficult in sealed devices
Solution Approach 1:
The patent introduces a porous gas-permeable membrane that allows generated gas bubbles to escape from the liquid phase while preventing liquid leakage. This membrane provides a controlled pathway for bubble removal, solving the problem of bubble accumulation in sealed devices while maintaining the energy efficiency of non-thermal bubble generation
Solution Approach 2:
The porous membrane acts as an intermediary between the liquid phase and the gas phase. It selectively allows gas molecules to pass through while blocking liquid, providing a simple and effective bubble removal mechanism that works with electrochemical gas generation methods
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 enables efficient directional fluid pumping in both open and closed configurations, addressing energy efficiency, thermal sensitivity, and bio-compatibility concerns, while utilizing the gaseous byproducts of fuel cell reactions to drive fluid circulation, particularly suitable for micro fuel cells like μDMFC.
Implementation Method 1
employing asymmetric channel structures and venting membranes to control bubble flow, allowing for the use of various bubble generation schemes like electrolysis
Implementation Method 2
allowing for the use of various bubble generation schemes like electrolysis, heating, or chemical reactions
Implementation Method 3
an asymmetric channel structure adjacent to a bubble provides higher capillary pressure on the smaller side. The bubble tends to grow along the larger microchannel
Implementation Method 4
The bubbles may be removed from the liquid flow by the use of one or more venting membranes
Data Source
AI summary
A method and device for the pumping of liquids utilizes the directional growth and elimination of gaseous vesicles or bubbles to provide the motive or pumping force. In one embodiment, the pumping device is a microfluidic pumping mechanism having a channel, a bubble generator for generating a plurality of bubbles within the channel, and a venting membrane disposed over a portion of the channel downstream of the bubble generator. A one-way valve or directional resistance feature is positioned upstream of the bubble generator to introduce directional transport of bubbles within the channel. The method and device may be integrated into micro fuel cells with organic liquid fuel such that liberated gaseous bubbles may be utilized to deliver fresh fuel or circulate reusable fuel without any power-consuming components.