CMOS-Compatible AlN Ultrasonic Transducers for Microfluidic Flow Control
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Solution Overview
Problem
Current microfluidic technologies face challenges in efficiently controlling and manipulating fluid flows at the microscale due to the need for mechanical valves and pumps, which increase device size, weight, and complexity, and often require external energy sources for mixing, limiting their portability and integration with CMOS-compatible materials.
Innovation Solution
The development of a planar semiconductor-based microfluidic flow control system using a linear array of Fresnel-type GHz ultrasonic transducers that generate localized acoustic streaming vortices, enabling valveless control and mixing without mechanical devices, and integrating with CMOS-compatible materials like aluminum nitride and silicon, allowing for electronic control of fluid flow and mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If mechanical valves and pumps are used for microfluidic flow control, then flow control capability is improved, but device size, weight, and complexity increase
Solution Approach 1:
The patent replaces mechanical valves and pumps with acoustic fields generated by ultrasonic transducers to achieve flow control, mixing, and particle manipulation. The ultrasonic transducers create acoustic radiation forces and acoustic streaming effects that eliminate the need for mechanical moving parts, thereby reducing device complexity while maintaining flow control capability.
Solution Approach 2:
The patent extracts the control function from mechanical components and implements it through acoustic fields. By removing mechanical valves and pumps and replacing them with ultrasonic-based control mechanisms, the system achieves simpler device architecture while preserving essential flow manipulation capabilities.
2Ease of operation
If mechanical valves and pumps are used for microfluidic flow control, then flow control capability is improved, but device size and weight increase
Solution Approach 1:
The patent replaces heavy mechanical valves and pumps with lightweight ultrasonic transducers and acoustic fields. The transducers generate acoustic radiation forces and streaming effects that control fluid flow without requiring mechanical moving parts, significantly reducing device weight while maintaining flow control functionality.
3Productivity
If external energy sources are used for mixing, then mixing efficiency is improved, but portability is reduced
Solution Approach 1:
The patent enables the microfluidic device to generate its own acoustic fields using integrated ultrasonic transducers that can be driven by standard voltage sources. This self-contained approach eliminates the need for external energy sources or complex power supplies, improving portability while maintaining mixing efficiency through acoustic streaming and radiation forces.
Solution Approach 2:
The patent replaces external mechanical mixing devices with acoustic field-based mixing using ultrasonic transducers. The acoustic radiation forces and streaming effects provide efficient mixing without requiring external energy sources or complex mechanical systems, thereby enhancing device portability.
4Power
If non-CMOS-compatible materials are used for transducers, then transducer performance is improved, but integration with CMOS is reduced
Solution Approach 1:
The patent employs aluminum nitride (AlN) piezoelectric material that is compatible with CMOS fabrication processes. AlN provides the necessary piezoelectric performance for ultrasonic transducer operation while being manufacturable using standard CMOS-compatible techniques, enabling seamless integration of high-performance transducers with CMOS electronics on the same substrate.
Solution Approach 2:
The patent selects aluminum nitride as the piezoelectric material, changing the material parameter from traditional non-CMOS-compatible materials like PZT to a CMOS-compatible alternative. This material substitution maintains the required piezoelectric coefficients for transducer performance while enabling integration with CMOS fabrication processes.
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 provides efficient, localized, and portable microfluidic control, enabling high-frequency mixing and particle manipulation with reduced size and cost, and allows for digital control of bio-chemical analytes in lab-on-chip environments, decoupling fluidics from electrical interconnects and using CMOS-compatible materials.
Implementation Method 1
an aluminum nitride based GHz bulk acoustic wave transducer placed in a Fresnel lens configuration... generates bulk acoustic waves through the silicon substrate adding in phase at the focus
Implementation Method 2
to realize a microfluidic actuator using acoustic radiation force and acoustic streaming
Implementation Method 3
Streaming vortices generated by high frequency focused bulk acoustic waves from Fresnel transducers perturb the laminar nature of the microfluidic flow in the channel
Implementation Method 4
Streaming vortices generated by high frequency focused bulk acoustic waves from Fresnel transducers perturb the laminar nature of the microfluidic flow
Implementation Method 5
The photoelastic effect in water is induced by a silicon based GHz bulk acoustic wave aluminum nitride transducer placed in a Fresnel lens configuration
Data Source
AI summary
In one aspect a high frequency ultrasonic microfluidic flow control device is disclosed. The device includes an array of ultrasonic transducers arranged to direct ultrasound to a microfluidic channel. The device further includes one or more driver circuits. Each ultrasonic transducer is associated with one of the one or more driver circuits, and each ultrasonic transducer is driven by a driver signal from the associated driver circuit. The array of ultrasonic transducers and one or more driver circuits are produced in the same semiconductor fabrication process. The device further includes one or more electrical contacts associated with each ultrasonic transducer in the array if ultrasonic transducers, wherein the one or more electrical contacts associated with each ultrasonic transducer applies the driver signal from the associated ultrasonic driver circuit.