Simulation and Printing of Microdroplets Using Straight Electrode-Based Electrohydrodynamic Jet for Flexible...

Area of Science:

• Materials Science and Engineering
• Nanotechnology and Microfabrication

Background:

• Electrohydrodynamic jet (e-jet) printing is a key technique for high-resolution microstructure fabrication, typically achieving features down to 10 μm.
• Current limitations in achieving nanoscale resolution (<100 nm) stem from fluid properties, voltage instability, and needle geometry.
• Flexible polymeric substrates present unique challenges for precise microscale printing.

Purpose of the Study:

• To overcome limitations in e-jet printing resolution and enable nanoscale feature fabrication.
• To develop an optimized e-jet printing process for flexible substrates using a novel electrode configuration.
• To validate simulation results with experimental printing of microdroplets.

Main Methods:

• A phase-field method was employed for simulating the electrohydrodynamic jet behavior.
• A novel combined needle and straight electrode design was introduced to stabilize the cone jet.
• Optimized parameters (flow rate f, needle voltage Vn, straight electrode voltage Vs) were determined through simulation and applied in experiments.

Main Results:

• Stable cone jet formation was achieved through the coupled electrode system at optimized parameters (f = 8.6 × 10−10 m3s−1, Vn = 9.0 kV, Vs = 4.5 kV).
• Direct printing of microdroplets smaller than 13 μm was successfully demonstrated on a flexible PET substrate.
• The developed model proved effective for printing versatile microstructures on polymeric materials.

Conclusions:

• The novel combined needle and straight electrode design significantly enhances control over e-jet printing.
• The phase-field simulation accurately predicts droplet formation, enabling process optimization.
• This method offers a powerful tool for fabricating microstructures in MEMS technology, including sensors and actuators.