Optical Heater Microfluidics Valve Actuation
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Solution Overview
Problem
Existing microfluidics valves based on paraffin wax are often single-use, have slow response times, and require challenging deposition of molten wax, with electrical heaters necessitating multiple electrical connections that increase cost and complexity, especially in disposable lab-on-a-chip systems.
Innovation Solution
A light-addressable microfluidics valve with a meltable material barrier, utilizing an optical heater that projects from both sides of the barrier to rapidly melt and eject the material, allowing fluid passage and re-sealing without electrical connections, using a photothermal material with a melting point between 50°C and 150°C, and optionally multiple heaters for pressure difference scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If electrical heaters are used to melt the wax barrier, then the valve can be actuated, but the device complexity and manufacturing cost increase due to requiring multiple electrical connections per heater
Solution Approach 1:
The patent replaces electrical heating systems with a mechanically/optically actuated system. A laser beam or optical heater melts the wax barrier without requiring electrical connections to the chip, substituting complex electrical infrastructure with a simpler optical actuation mechanism that can be controlled externally.
Solution Approach 2:
The patent extracts the heating function from the chip structure itself by using an external optical heater or laser beam that acts on the wax barrier from outside the chip. This removes the need for integrated electrical heaters and their associated electrical connections, simplifying the chip design.
2Ease of operation
If electrical heaters are used in disposable lab-on-a-chip systems, then valve control is achieved, but the manufacturing cost increases due to connectors with many pins
Solution Approach 1:
The heating function is extracted from the disposable chip and placed in an external device (optical heater or laser source). This allows the chip itself to remain simple and connectorless, while the expensive optical actuation system is reused across multiple disposable chips, reducing per-unit manufacturing costs.
Solution Approach 2:
A single optical heater or laser source can actuate multiple valves across different chips or on the same chip, providing a universal actuation mechanism that reduces the need for individual electrical connections per valve, thereby lowering manufacturing complexity and cost.
3Ease of operation
If conventional wax valves are used, then flow control is achieved, but the response time is slow
Solution Approach 1:
The patent changes the thermal parameters of the system by using optical heating which delivers energy more rapidly and locally to the wax barrier. This concentrated optical energy heating method raises the heating rate parameter, enabling faster melting and thus faster valve response compared to conventional electrical heating.
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
The valve achieves fast response times, low energy consumption, and multiple actuations with reduced complexity and cost, being leak-proof and suitable for high-integration applications like lab-on-a-chip systems and samplers, with opening and closing times of approximately 100 ms and 500 ms respectively, and energy consumption under 1 J.
Implementation Method 1
an optical heater that projects from both sides of the barrier to rapidly melt and eject the material
Implementation Method 2
a barrier of a meltable material is placed in a microchannel. At the usual working temperature, the meltable material is blocking the passage of fluid through the microchannel. In order to allow the fluid passage through the microchannel, the meltable material, has to be heated.
Data Source
Figure 1a
Figure 1b~1c
Figure 2a~2b
AI summary
A microfluidics valve comprises at least two substrates (1) between which there is at least a microchannel (5). It additionally comprises at least a barrier (4) of a meltable material, placed in the microchannel. The valve further comprises at least an optical heater (6) placed in correspondence with the barrier (4) and at least a section of one of the substrates (1), in correspondence with the optical heater (6), is transparent. The optical heater is a colored line that, when is illuminated with a light source, is heated and releases the heat to the barrier (4) thus melting the part of it that is closer to the line.