Capillary-Stop Valve Activation via Electrostatic Liquid Attraction
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Solution Overview
Problem
Existing micro fluidic devices with capillary-stop valves lack user-activated control over liquid flow, limiting the ability to initiate liquid discharge from the container.
Innovation Solution
Incorporating a first electrode in contact with the liquid and a second electrode spaced by an electrically insulating gap, connected to a voltage source, to apply an electric potential difference that attracts the liquid and overcomes the capillary-stop valve's stopping effect, allowing controlled discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a capillary-stop valve is used to stop liquid flow, then the liquid remains contained in the reservoir, but the user cannot activate liquid discharge at will
Solution Approach 1:
The patent replaces the traditional mechanical valve structure with an electrostatic actuation system. Two electrodes generate an electric field that applies electrostatic force to the liquid meniscus at the capillary outlet, enabling user-controlled discharge without mechanical moving parts. This resolves the contradiction by eliminating mechanical complexity while providing ease of operation through electrical control.
Solution Approach 2:
The patent changes the physical state or parameters of the liquid interface by applying electrostatic force. The electric field modifies the contact angle and surface tension characteristics of the liquid at the capillary outlet, enabling controlled discharge. This parameter change approach allows simple electrical activation without complex mechanical valve mechanisms.
2Ease of operation
If electrodes are placed close to the capillary-stop valve to attract liquid, then liquid discharge is enabled, but the risk of electrical discharge or breakdown increases
Solution Approach 1:
The patent introduces the liquid itself as an intermediary medium between the electrodes. The liquid forms a conductive bridge that allows controlled electrical discharge only when desired, while the gas gap prevents unwanted discharge. This intermediary approach enables safe electrical control by using the liquid's own properties to mediate the electrical interaction.
Solution Approach 2:
The patent utilizes the gas gap (air or other gas) as an electrical insulator to prevent electrical breakdown. By maintaining a gas-filled space between the electrode and capillary outlet, the system achieves electrical isolation while still allowing electrostatic influence on the liquid. This pneumatic approach solves the electrical discharge risk by using gas properties for insulation.
3Reliability
If a gas gap is maintained between the second electrode and liquid, then electrical insulation is provided, but the electrode cannot directly attract the liquid
Solution Approach 1:
The patent segments the electrical field interaction into two distinct zones: a gas-filled insulation zone and a liquid-filled attraction zone. The first electrode contacts the liquid directly for strong electrostatic attraction, while the second electrode maintains a gas gap for insulation. This segmentation allows both electrical insulation and effective attraction force to coexist by separating their functional locations.
Solution Approach 2:
The patent utilizes the spatial dimension created by the gas gap to resolve the contradiction. The electric field penetrates through the gas gap to act on the liquid, allowing the second electrode to be positioned on the opposite side of the capillary outlet. This dimensional arrangement enables both insulation (via gas gap distance) and attraction (via field penetration) simultaneously.
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 user-controlled liquid flow by increasing the contact angle or attracting the liquid to a second electrode, ensuring reliable discharge without moving parts, and allows for detection of valve activation without chemical reactions.
Implementation Method 1
a voltage source connected to said first and second electrode which is activatable for applying an electric potential difference at the first and second electrode such that the liquid in the liquid container is attracted in the direction of said second electrode
Implementation Method 2
Such capillary-stop valves function by introducing an abrupt increase in the effective contact angle between the liquid and the inner surface of the capillary-stop valve
Implementation Method 3
a capillary-stop valve that refers to both a capillary valve and a hydrophobic valve
Data Source
AI summary
The invention relates to a device (20), comprising:a liquid container (21) for containing a liquid;a capillary-stop valve (22) that is in medium through flow connection with said liquid container (21) for stopping said liquid in said container from flowing out of said container via said capillary-stop valve (22);a first electrode (7) being arranged such that in use said first electrode is in contact with said liquid in said liquid container;a second electrode (2) that is spaced apart from said capillary-stop valve by an electrically insulating medium gap (24), anda voltage source (V) connected to said first and second electrode which is activatable for applying an electric potential difference at the first and second electrode such that the liquid in the liquid container is attracted in the direction of said second electrode so as to allow the liquid to overcome the stopping effect of the capillary-stop valve for discharging liquid from said liquid container via said capillary-stop valve. The invention also relates to a method for activating a capillary-stop valve of a device.