E-Nanoprint-Pro
For a touchscreen—an essential component of a smartphone—to function properly, a layer that combines good electrical conductivity with optical transparency is required. Today, such layers are typically made of indium tin oxide (ITO).
The E-Nanoprint-Pro project was completed in 2022
However, the industry faces several challenges: the supply of indium is limited, the ITO layer is expensive and fragile, and the ITO manufacturing process is harmful to the environment. As a result, the display industry is actively seeking alternative solutions.
New nanoprinting technology could provide such a solution. Conductive and optically transparent layers could be created by printing a mesh of wires. Obviously, these wires must be very thin while offering high conductivity. An additional benefit is that these printed wires are better suited for use on flexible substrates, which aligns well with the trend toward flexible displays. Printed wires with nanoscale dimensions, produced using a novel process called Near-Field Electro-Hydrodynamic Nanowire Printing (ENP), promise to be the ideal choice for this application. The introduction of printed solutions in the display industry aligns well with the industry’s trend toward adopting additive manufacturing processes.
The principle behind ENP has been known for decades and is used to produce filters and nonwovens for the textile industry. Electrospinning can be used to produce sub-micrometer-thin fibers. A typical electrospinning setup consists of a syringe pump, a high-voltage power supply, a needle, and a collector. Traditionally, a rather chaotic, random deposition of fibers occurs at a relatively far-field spinning distance of about 300 mm and under an electrostatic voltage of 20K to 30K. A relatively new development in the ENP process is near-field printing at a distance of about 10 to 20 mm and voltages up to about 4 kV. This enables controlled fiber deposition for patterning and masking in a lithographic process or for the direct deposition of functional materials.
As part of the E-Nanoprint-Pro project, DoMicro, Coatema, microTEC, tec-V, and TechToBizz are collaborating on the development of a nanoprinter prototype—a desktop system for printing fibers in lines with nanoscale widths. The project is being carried out as part of the RocKET Reloaded program[1], an initiative for regional collaboration on key enabling technologies involving German and Dutch companies. The program has been instrumental in bringing together partners across borders, identifying promising market applications, and accelerating the project.
In addition to developing the prototype, the project partners are exploring several promising applications that this new technology could enable. One such application is the printing of conductive wires for microfluidic devices. Printing these wires at the nanoscale allows for significant miniaturization of such devices, which could make it possible to use them inside the body. Furthermore, the project anticipates the introduction of nanoprinting on an industrial scale.
Further promising applications in the industry are anticipated in electronics, life sciences, and energy. Examples include conductive electrodes for OLED displays as well as transistors on flexible substrates.
A key focus of the project is process development, which is necessary to bring this entirely new printing process to a reliable and controllable level. Over the course of the project, appropriate and stable process settings have been identified for printing nanowires in a controlled manner on conductive and insulating substrates.
These results show that the new nanoprinter is suitable for use in research laboratories seeking to study the deposition of advanced materials. DoMicro plans to launch this first ENP nanoprinter in mid-2021.