Microfluidic Device Bonding via UV Adhesive Protrusions
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Solution Overview
Problem
Existing microfluidic device fabrication methods, such as ultrasonic welding and thermal bonding, face challenges with reagent vaporization, high energy requirements, and poor bonding reliability due to air bubbles and adhesive overflow, which affect the integrity of microfluidic structures and fluid containment.
Innovation Solution
A microfluidic device is fabricated using two substrates bonded with a UV-curable adhesive, where the lower substrate features protrusions to support the upper substrate only at specific points, minimizing adhesive usage and preventing air bubble formation, and the adhesive is applied using an inkjet method to control the amount and placement, ensuring reliable bonding without high temperature or energy-intensive processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ultrasonic welding method is used to bond substrates, then bonding strength is improved, but reagent vaporization and degeneration occur due to strong ultrasonic energy
Solution Approach 1:
The patent replaces the mechanical ultrasonic welding system with a chemical bonding system using adhesive. The adhesive is applied in groove structures that guide and contain it, eliminating the need for ultrasonic mechanical energy that causes reagent vaporization while still achieving reliable substrate bonding.
Solution Approach 2:
The patent introduces adhesive as an intermediary substance between the substrates. This adhesive mediator performs the bonding function without requiring direct mechanical energy transfer between substrates, thereby avoiding reagent vaporization while maintaining bonding strength.
2Reliability
If thermal bonding or laser welding method is used, then bonding reliability is improved, but high temperature and high energy conditions make it difficult to manufacture devices with liquid reagents
Solution Approach 1:
The patent replaces thermal bonding and laser welding methods with chemical adhesive bonding. This substitution eliminates the need for high temperature and high energy conditions, allowing liquid reagents to remain in chambers without vaporization or degradation while achieving reliable substrate bonding.
Solution Approach 2:
The patent changes the bonding parameter from high temperature/high energy (thermal or laser) to room temperature chemical bonding using adhesive. This parameter change enables the presence of liquid reagents during the bonding process without causing vaporization or degradation.
3Reliability
If liquid adhesive is injected into grooves to bond substrates, then bonding is achieved, but large amounts of adhesive are required and overflow may close fine channels
Solution Approach 1:
The patent segments the bonding area into specific groove structures that are strategically positioned around chamber and channel perimeters. This segmentation allows adhesive to be applied only where needed for structural bonding, minimizing the total adhesive quantity while preventing overflow into fine channels.
Solution Approach 2:
The patent applies adhesive locally in groove structures at specific locations (chamber perimeters, channel perimeters) rather than uniformly across entire substrate surfaces. This local application reduces the total adhesive quantity required while maintaining bonding reliability at critical interfaces.
4Ease of manufacture
If adhesive bonding is used to join substrates, then manufacturing complexity is reduced, but air bubbles form on bonding surfaces degrading bonding reliability
Solution Approach 1:
The patent performs preliminary action by creating groove structures on substrate surfaces before adhesive application. These grooves serve as adhesive containment channels that guide the adhesive and prevent air bubble formation, thereby maintaining bonding reliability while keeping the manufacturing process simple.
Solution Approach 2:
The groove structures act as intermediary elements between the adhesive and the substrate surface. They guide the adhesive flow and provide a defined path that prevents air bubbles from becoming trapped, thereby maintaining bonding reliability without complicating the overall manufacturing process.
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 method enhances bonding reliability by preventing air bubble formation and reagent degradation, allowing for precise and efficient assembly of microfluidic devices with improved fluid containment and operational stability.
Implementation Method 1
the adhesive is applied using an inkjet method to control the amount and placement, ensuring reliable bonding without high temperature or energy-intensive processes
Data Source
AI summary
A microfluidic device and a method of fabricating the microfluidic device are provided. The microfluidic device includes: a platform including an upper substrate and a lower substrate that are bonded to face each other; a microfluidic structure obtained by forming grooves in the lower substrate; a lower substrate protrusion pattern including an outline protrusion that protrudes from the lower substrate toward the upper substrate along an outline of the microfluidic structure; and an adhesive layer disposed between the lower substrate protrusion pattern and the upper substrate in order to bond the upper substrate and the lower substrate to each other. The lower substrate protrusion pattern only supports the upper substrate, and remaining portions of the lower substrate except for the lower substrate protrusion pattern do not have structures for supporting the upper substrate.