Microfluidic Nozzle Formation Using Segmented Metal Layers
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Solution Overview
Problem
Current methods for forming nozzles in microfluidic and micromechanical chambers require large amounts of gold, leading to high manufacturing costs and complex, time-consuming processes, especially in applications like inkjet printers and DNA amplification, where precise temperature control is necessary.
Innovation Solution
A method involving the formation of a sacrificial pillar surrounded by a non-gold metal layer, such as tungsten or aluminum, which is later removed to create the nozzle, reducing gold usage and simplifying the manufacturing process, while a thin gold protection layer is used to coat the nozzle for corrosion protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large gold layer is deposited to form nozzle walls, then the nozzle provides adequate heat sink protection, but the manufacturing cost increases significantly
Solution Approach 1:
The nozzle structure is segmented into two functional layers: a thick non-gold metal layer (15-17 microns) providing heat sink protection and structural support, and a thin gold protection layer (0.2-1 microns) providing corrosion resistance. This segmentation allows each material to perform its optimal function while minimizing gold usage from 17 microns to just 0.2-1 microns.
Solution Approach 2:
Different materials are applied to different regions of the nozzle with specific properties: the thick non-gold metal layer is applied where heat dissipation is needed, while the thin gold layer is applied where corrosion protection is required. This local quality assignment optimizes both performance and cost.
2Stability of the object's composition
If a large gold layer is deposited to form nozzle walls, then the nozzle structure is stable, but the manufacturing process becomes more complex and time-consuming
Solution Approach 1:
The manufacturing process is segmented into distinct deposition steps: first depositing the thick non-gold metal layer, then depositing the thin gold protection layer. This segmentation simplifies process control compared to depositing a single thick gold layer, as each layer can be optimized independently for its specific function.
Solution Approach 2:
The material composition parameter is changed from pure gold to a composite structure of non-gold metal plus thin gold layer. This parameter change maintains structural stability while reducing process complexity and cost.
3Temperature
If a thick metal layer is used as heat sink, then high heater temperatures are tolerated, but the amount of material required increases
Solution Approach 1:
The thick non-gold metal layer (15-17 microns) is specifically positioned at the nozzle walls where heat sink functionality is required. This local application of thick metal provides adequate heat tolerance while minimizing overall material usage compared to coating entire structures.
Solution Approach 2:
The nozzle structure uses a composite material system where a non-gold metal provides thermal management properties, and a thin gold layer provides corrosion resistance. This composite approach achieves both high temperature tolerance and chemical stability with reduced total material volume.
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 approach significantly reduces the cost and time required for nozzle formation, maintaining the benefits of gold while minimizing its use, thus lowering overall production costs and simplifying the manufacturing process.
Implementation Method 1
Portions of the sacrificial layer are etched, re-exposing the passivation layer and leaving a pillar of sacrificial material positioned overlying the chamber
Implementation Method 2
a metal layer is deposited on the passivation layer and around the pillar
Implementation Method 3
A protection layer is then deposited over the metal layer as a protection from the corrosive properties of the fluid that will pass through the nozzle
Data Source
AI summary
A method that includes forming a chamber in a substrate, forming a silicon layer overlying the chamber, etching the silicon layer to remove selected regions and retain a selected portion overlying the chamber, the selected portion being at a location and having dimensions that correspond to a location and to dimensions of a nozzle, and forming a first metal layer adjacent to the selected portion. The method also includes forming a path in the substrate to expose the chamber concurrently with removing the selected portion of the silicon layer to expose the nozzle, the nozzle being in fluid communication with the path, the chamber, and a surrounding environment.