Electrohydrodynamic 3D Printing of High Viscosity Polymers
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Solution Overview
Problem
Current additive manufacturing techniques face limitations in printing high viscosity materials due to the dependence of droplet diameter on nozzle size, difficulty in scaling down nozzle diameters, and the need for high driving power, which restricts the achievement of raster widths less than 20 μm and leads to degraded resolution from droplet spreading.
Innovation Solution
An electrohydrodynamic 3D printing system with a reservoir and a discharge nozzle, where a heating coil heats the material, and an electric potential supply generates an electric field to control the jetting process, allowing for the production of droplets with widths less than 10 microns and enabling high resolution printing of high viscosity materials without the need for back pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional inkjet printing is used to print high viscosity materials, then droplets can be deposited on substrate, but droplet diameter is solely dependent on nozzle diameter and cannot be scaled down easily
Solution Approach 1:
The patent replaces the conventional mechanical pressure-driven droplet ejection system with an electrohydrodynamic system. A high voltage electric field (several kV) is applied between the nozzle and substrate to generate electrostatic forces that pull the material through the nozzle and form charged droplets. This substitution of mechanical pressure with electrical fields enables precise control of droplet size independent of nozzle diameter, achieving sub-10 μm droplets with 100 μm nozzles.
Solution Approach 2:
The patent changes the physical parameters of the system by introducing high voltage electric fields (several kV) and controlling the distance between nozzle and substrate (10-100 μm). By adjusting these electrical and geometric parameters, the droplet diameter can be precisely controlled to be much smaller than the nozzle diameter, overcoming the conventional limitation where droplet size is directly tied to nozzle size.
2Ease of operation
If large nozzle diameter is used to permit pumping of viscous materials, then high viscosity materials can be delivered, but raster linewidth cannot be less than 20 μm and resolution is degraded
Solution Approach 1:
The patent replaces mechanical pressure pumping with electrohydrodynamic forces. The high voltage electric field generates electrostatic attraction that pulls viscous materials through the nozzle without requiring mechanical pressure. This allows the use of larger nozzles (100 μm) for easy material delivery while the electrostatic control produces fine droplets (sub-10 μm) for high resolution printing.
Solution Approach 2:
The patent introduces an electric field as an intermediary between the nozzle and substrate. This electric field acts as a mediator that controls the material flow and droplet formation process, enabling the decoupling of nozzle size from droplet size. The electric field allows viscous materials to be delivered through large nozzles while maintaining precise control over the final droplet dimensions.
3Productivity
If thermal or piezoelectric means are used to force droplets from nozzle, then droplet ejection is achieved, but large driving power is required and droplet diameter is approximately double the nozzle diameter
Solution Approach 1:
The patent replaces thermal heating elements or piezoelectric actuators with an electrohydrodynamic system. Instead of using thermal energy to expand air bubbles or piezoelectric energy to mechanically squeeze droplets, the system uses high voltage electric fields to generate electrostatic forces. This substitution reduces the driving power requirement while enabling precise droplet size control that is not limited to being double the nozzle diameter.
Solution Approach 2:
The patent changes the energy input parameter from thermal/piezoelectric to high voltage electrical. By applying several kV electric fields, the system generates sufficient force to eject viscous materials without requiring the large driving powers associated with thermal or piezoelectric methods. The electric field parameters (voltage, distance) can be optimized to achieve efficient droplet ejection with reduced energy consumption.
4Speed
If high speed droplet deposition is used, then printing speed is improved, but resolution is further degraded by spreading of droplets on substrate
Solution Approach 1:
The patent changes the droplet characteristics by using electrohydrodynamic ejection to produce highly charged, smaller droplets (sub-10 μm). These modified droplet parameters reduce the tendency for spreading upon substrate contact. Additionally, the controlled droplet ejection speed and trajectory, governed by electric field parameters, allow optimization of deposition speed while maintaining sharp features and minimizing spread.
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
The system achieves high resolution raster widths and efficient printing of high viscosity materials, overcoming the limitations of traditional methods by controlling jet stability and optimizing parameters for geometry, material properties, and printing processes, allowing for precise deposition of features below 100 μm.
Implementation Method 1
A heating coil is disposed proximate to the discharge nozzle. The heating coil is configured to heat the reservoir proximate to the discharge nozzle.
Implementation Method 2
An electrohydrodynamic 3D printing system comprising a reservoir having a discharge nozzle... An electric potential supply has a first electrode electrically connected to the discharge nozzle and a second electrode electrically connected to the collector plate
Data Source
AI summary
A system and method for three-dimensionally printing high viscosity materials using electrohydrodynamics is provided. The system uses a relatively low voltage electric field to draw high viscosity polymers (not in solution) from a nozzle to form three-dimensional objects with lines less than 10 microns in width. Pressurized gas at the nozzle outlet can be used to print large size/dimension parts, instead of or in addition to the electric field to draw the polymers from the nozzle.