Programmable Hydraulic Resistor Array for Flexible Microfluidic Flow Control
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Solution Overview
Problem
Microfluidic devices lack flexibility in adjusting assay conditions during operations due to fixed flow paths and limited dynamic range of liquid flow rates, which restricts their ability to mix liquids, control biological reactions, and vary liquid concentrations effectively.
Innovation Solution
A microfluidic chip with a hydraulic resistor structure and actuatable valves that can modify the effective hydraulic resistance after fabrication, allowing for programmable control of flow rates by actuating valves, enabling a wide range of flow rates and flexible operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If flow paths are fixed during microfabrication, then manufacturing precision is improved, but adaptability deteriorates
Solution Approach 1:
The flow path is segmented into multiple parallel channels, each with its own valve. This allows the continuous flow path to be divided into controllable segments, enabling dynamic reconfiguration of flow routes and rates while maintaining precise manufacturing of each individual channel.
Solution Approach 2:
Static flow paths are transformed into dynamic, reconfigurable flow networks by integrating actuatable valves at strategic locations. The valves enable the system to adapt flow rates and routes in real-time, converting a fixed manufacturing structure into a dynamically adjustable fluid control system.
2Ease of operation
If mechanical valves are used to control flow rate, then ease of operation is improved, but device complexity increases
Solution Approach 1:
Traditional mechanical valves with moving parts are replaced by electrowetting-based valves that use electrical fields to modulate surface tension and control fluid flow. This substitution eliminates complex mechanical components while providing precise electronic control of flow rates.
Solution Approach 2:
The valve mechanism changes the physical state or properties of the fluid interface through electrowetting, altering surface tension parameters to control flow. This parameter-based control replaces mechanical displacement with electrical field modulation, simplifying the valve structure.
3Ease of operation
If pneumatic valves are integrated into microfluidic chip, then ease of operation is improved, but manufacturing precision deteriorates
Solution Approach 1:
Pneumatic valves requiring complex multi-layer deformable structures are replaced with electrowetting valves that use electrical fields to control fluid flow. This eliminates the need for complex pneumatic chambers and deformable membranes, significantly simplifying the fabrication process while maintaining flow control capability.
Solution Approach 2:
The complex pneumatic actuation system with its multiple layers and deformable materials is extracted and removed from the microfluidic chip design. The essential flow control function is retained through a simpler electrowetting mechanism that does not require pneumatic infrastructure.
4Ease of manufacture
If torque-actuated valves are used, then ease of manufacture is improved, but adaptability deteriorates
Solution Approach 1:
Manual torque-actuated valves are replaced with electronically controlled electrowetting valves. The electronic control capability is integrated directly into the valve mechanism, enabling programmable flow rate adjustment and real-time adaptation to different assay conditions while maintaining ease of manufacture through simple planar fabrication.
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 solution allows for precise control of flow rates and concentrations, enhancing the dynamic range of liquid flow, making it suitable for point-of-care diagnostics and applications like DNA hybridization and immunoassays, where convection and diffusion play critical roles.
Implementation Method 1
The valve includes a gate and means for modulating a contact angle of the gate with the liquid. In one embodiment, the valve is an electrowetting valve including a gate and means for modulating a contact angle of the gate with the liquid by applying a voltage between the gate and the liquid.
Data Source
AI summary
Embodiments of the invention provide a microfluidic chip having microfluidic structures formed on a surface. The structures form an input channel, an output channel, auxiliary channels, and a hydraulic resistor structure connecting the input channel to the output channel via the auxiliary channels. The resistor structure includes N flow resistor portions (N≥2), which are connected to the auxiliary channels. The chip further includes at least N−1 actuatable valves, which are arranged in respective ones of the auxiliary channels. The actuation state of the valves can determine the effective hydraulic resistance of the resistor structure. The valves can be electrogates, each including a liquid-pinning trench arranged in a respective one of the auxiliary channels that define a flow path for a liquid introduced therein, so as to form an opening that extends across said flow path. Each electrogate can further include an electrode extending across the flow path.