Micro-Fluidic Thermal Inkjet Print Head Viscosity Control
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Solution Overview
Problem
Existing dispensing systems face challenges in depositing viscous materials onto a substrate without degrading nozzle performance, particularly with high viscosity fluids that do not flow easily through the system.
Innovation Solution
A fluid delivery system using a micro-fluidic thermal inkjet print head with heating elements and a controller to reduce fluid viscosity by heating it to a specific temperature, combined with controlled nozzle firing frequencies and additional fluid recirculation channels to manage shear forces and maintain optimal viscosity for ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If thermal heating is applied to reduce fluid viscosity, then fluid flow improves, but energy consumption increases
Solution Approach 1:
The system pre-heats the fluid before it reaches the nozzle to reduce viscosity and improve flow. By performing the heating action in advance rather than continuously during operation, the system reduces overall energy consumption while maintaining optimal fluid flow characteristics when needed.
Solution Approach 2:
The heating elements operate periodically rather than continuously, activating only when fluid viscosity requires reduction. This periodic heating approach maintains fluid flow while minimizing energy consumption by avoiding constant thermal input.
2Productivity
If high viscosity fluid is forced through the system, then material deposition is achieved, but nozzle performance degrades
Solution Approach 1:
The system changes the temperature parameter of the fluid to reduce viscosity before ejection. By heating the fluid to an optimal temperature range, the system enables high viscosity materials to flow through the nozzle without causing performance degradation, while still achieving effective material deposition on the substrate.
Solution Approach 2:
The fluid is pre-conditioned through heating before reaching the nozzle, reducing viscosity in advance to prevent nozzle clogging and performance degradation during the deposition process.
3Manufacturing precision
If heating elements are used to control fluid viscosity, then deposition precision improves, but device complexity increases
Solution Approach 1:
The heating elements serve multiple functions: they control fluid viscosity for precise deposition, maintain optimal flow characteristics during operation, and can be integrated with existing thermal management systems. This multi-functionality reduces overall device complexity despite the added precision capability.
Solution Approach 2:
The heating elements are integrated directly into the fluid delivery system and nozzle structure, combining thermal control and fluid ejection functions into a unified system. This integration reduces the number of separate components and simplifies the overall device architecture while maintaining deposition precision.
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
Enables the precise and efficient deposition of viscous materials onto a substrate while minimizing nozzle performance degradation and ensuring consistent fluid flow, even with high viscosity fluids.
Implementation Method 1
reduce fluid viscosity by heating it to a specific temperature
Implementation Method 2
heating of a volatile carrier to form a transport jet
Data Source
AI summary
A fluid dispensing method, the method comprising steps of: providing a system comprising a reservoir, a micro-fluidic thermal inkjet print head in fluid communication with the reservoir, a controller and a power source in electrical communication with the controller and the print head, the reservoir containing a fluid, the micro-fluidic thermal inkjet print head comprising nozzles; heating the fluid in the microfluidic device to a temperature of about 40 C to 75 C in less than about 1000 ms; activating the print head to fire the nozzles about 200 fires/nozzle at a first frequency; subsequent to step c, activating the print head to fire the nozzles at a second frequency, the second frequency substantially less than the first frequency; and subsequent to step d, activating the print head to fire the nozzles at a third frequency substantially greater than the first frequency.