E-jet Printing Current Feedback Control
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Solution Overview
Problem
Conventional E-jet printing systems lack real-time feedback control, leading to inefficiencies in print resolution, precision, and speed, with limitations in droplet size control and printing frequency, particularly at high speeds and sub-micron scales.
Innovation Solution
The implementation of current-based detection and control systems that monitor and adjust electrical parameters such as voltage and current in real-time to optimize E-jet printing, enabling high-resolution, high-speed, and precise droplet deposition by modulating process parameters like input voltage, current, and stand-off height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional sensing and monitoring techniques such as image processing are used, then printing can be performed, but real-time feedback control is not achieved and data analysis requires offline processing
Solution Approach 1:
The patent replaces optical/image processing systems with electrical sensing systems. Current sensors monitor the electrical current during E-jet printing in real-time, converting the sensing mechanism from optical to electrical domain. This substitution enables immediate detection of printing parameters without the delays inherent in image capture and offline analysis, achieving real-time feedback control.
Solution Approach 2:
The patent implements a closed-loop feedback system where current sensors continuously monitor printing parameters during E-jet operation. The real-time current data is fed back to the control system, which automatically adjusts printing parameters to maintain optimal performance. This feedback mechanism eliminates the need for offline analysis by providing continuous real-time monitoring and correction.
2Manufacturing precision
If E-jet printing is performed without real-time control, then system complexity is reduced, but printing resolution and precision deteriorate
Solution Approach 1:
The patent replaces complex optical monitoring and analysis systems with simpler electrical current sensing. By monitoring electrical current characteristics during printing, the system achieves high-resolution control without requiring complex image processing hardware and software, thus improving precision while managing system complexity.
Solution Approach 2:
The E-jet printing system uses its own electrical current characteristics as the sensing signal. The same electrical field that drives the jetting process also produces measurable current variations that indicate printing status. This self-service approach eliminates the need for separate sensing systems, achieving high precision without proportionally increasing system complexity.
3Productivity
If higher printing frequencies are used to increase throughput, then productivity is improved, but droplet size control and printing precision worsen
Solution Approach 1:
The patent implements real-time feedback control using current sensors that monitor droplet ejection at high frequencies. The system detects current variations corresponding to individual droplet formation and ejection events, enabling precise control of droplet size and spacing even at kHz printing frequencies. This feedback mechanism maintains precision by continuously adjusting parameters based on real-time detection.
Solution Approach 2:
The patent employs periodic pulsed voltage signals to control droplet ejection at high frequencies. By using precisely timed periodic voltage pulses, the system achieves consistent droplet formation and ejection at controlled intervals, maintaining both high printing frequency and precise droplet size control through regular periodic actuation.
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 enhances printing resolution, precision, and speed, allowing for consistent and reliable droplet placement with frequencies up to kHz and volumes as low as 1×10−6 pL, overcoming the limitations of traditional systems by enabling on-the-fly adjustments and improved manufacturing throughput.
Implementation Method 1
An electric potential difference is provided or established between the nozzle and the substrate surface to establish an electrostatic force to said printable fluid in the nozzle, thereby controllably ejecting the printable fluid from the nozzle onto the substrate
Implementation Method 2
current-based detection is used to monitor the e-jet printing performance and optimize printing by controlling a process parameter
Data Source
AI summary
Provided are various methods and devices for electrohydrodynamic (E-jet) printing. The methods relate to sensing of an output current during printing to provide control of a process parameter during printing. The sensing and control provides E-jet printing having improved print resolution and precision compared to conventional open-loop methods. Also provided are various pulsing schemes to provide high frequency E-jet printing, thereby reducing build times by two to three orders of magnitude. A desktop sized E-jet printer having a sensor for real-time sensing of an electrical parameter and feedback control of the printing is provided.