It seems that the list of things that can be 3D printed just keeps growing, and the things on that list just keep getting stranger. Researchers from the University of Massachusetts in Lowell have developed a new programmable 3D printing material that can be used to manufacture several vital components for radar systems. The process would replace the need for many of the typical electronics used in modern radar systems and replace them with 3D printed sheets of plastic material. This new manufacturing method would not only make radar significantly cheaper, but the material is extremely versatile and would allow radar emitting, or cancelling, coatings to be 3D printed on most flat surfaces.
While there are several 3D printable conductive materials already available, they are often limited in what they can be used for and are generally only useful for basic or simple electronic functions. In order to 3D print the high level electronics required to deal with high-frequency radio waves it would require the use of materials capable of printing objects with very specialized electrical properties. The UMass Lowell researchers believe that they have developed a new “functional ink” that can be manually tuned to detect radio waves and generate the specific frequencies required for a functional radar system.
These inks can be used to fabricate a surface that is both capable of transmitting radio waves and sensitive enough to detect the waves that return after colliding with an object in their path. Electronics sophisticated enough to work with radar capable surfaces typically rely on materials that require the use of high-temperature manufacturing techniques that would destroy any plastics. The 3D printable electrically conductive inks that already exist contain standard metallic nanoparticles bonded inside of plastics that can be printed at lower temperatures. Unfortunately they are only capable of basic electrical functionality ill suited to the selective frequency surfaces needed for advanced radar systems.
According to Christopher McCarroll, co-director of the Raytheon UMass-Lowell Research Institute, the new ink that his team of researchers developed can be 3D printed and cured at temperatures far lower than were previously possible. The new ink is made of tiny nanoparticles of a specialized electrically conductive material that is suspended inside of a thermoplastic polymer. The material can be programed to both detect and absorb specific radar signals and frequencies on the printed surface. Theoretically, this means that the entire surface of a vehicle can be coated with a radar emitting material, or even programmed to absorb radar waves, making them virtually radar invisible.
In order for the material to emit and detect radar waves, the flat surface needs to be capable of altering the amount and frequency of radio waves that pass through it. This is usually done with a voltage-variable capacitor, or sometimes called a varactor. The inks developed by the UMass researchers can be used to 3D print a material capable of controlling that flow of radio waves. The researchers say that this is the first entirely 3D printed varactor, which is an essential electrical component for the type of tunable electronic devices used in military radar systems.
Another essential component for high level electronics is a phase shifter that can electronically direct conduct the radar frequencies needed for most phased-array radar systems to work. The new inks can be used to 3D print these frequency-selective surfaces that can be programmed to ignore unessential frequencies of electromagnetic radiation. Without the ability to filter out unwanted radiation the radar system would be useless. With the ability to replicate both of these functions, the inks can 3D print not only radar systems, but they can be used to develop self-driving cars, automobile collision-avoidance systems, cell-phone towers and even help shield hospitals and other buildings from unwanted radiation.
Currently the research team is combining two different machines to 3D print these electronic surfaces with their inks. They are using an aerosol-jet 3D printer that shoots streams of gas to deposit a conductive ink made of silver and then a printer that uses tiny vibrations to deposit their new inks. However the team is still experimenting with the new materials to try and find a more optimal deposition technique. They are also exploring the possibility of 3D printing all of the electronic components in a radar system, including the high-powered computer chips. McCarroll is also developing ways to marry his new 3D printed radar conductive surfaces with other traditional components. Discuss in the 3D Printing Material for Radar Systems forum over in 3DPB.com.
Here is some video of the inks being used to 3D print the complex electronics: