We just printed the microphone on a 3D printer in the laboratory - and then there will be full science fiction

Original author: Andrew Reid
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The idea of ​​creating a physical object from a digital file seems exciting. She recalls Star Trek replicators that can do anything from clothing to parts for a spaceship and food. Today's 3D printing is taking impressive steps in this direction, which is of great interest to many manufacturers. For example, it became possible to print the components of complex electronic devices on relatively simple equipment - as my research team just demonstrated , by creating, in our opinion, the first microphone printed on a 3D printer.

Quite a lot of different materials are already available for 3D printing., including those similar to wood and silver. However, most machines are limited to working with synthetic materials - plastic, rubber polymers and nylon. Typically, machines print only one material at a time, or switch over a palette of two to three materials. But this still leaves great potential, especially for giving materials different properties. This can be achieved by mixing nanoparticles of another material that has the properties you need.


If, for example, you want your material to conduct current, you can add silver, gold or carbon nanotubes to it. This makes it possible to print electronic circuits. If you need piezoelectricity — the generation of electricity by compression — you can add barium titanate to the material. The resulting object can be turned into a sound or heat sensor, or into a power drive, a device that makes other components move.

Switching between circuits, sensors and actuators during a single print, you can create a working electronic component as a whole. In recent years, people have used this technique to make things like optical components for lenses or panels, or accelerometers , for example- devices that measure the movement of various objects, from a running person to earthquakes. She also allowed us to create our microphone, translate it from a digital file into reality in just six hours.

File your plastic


Ideally, we would like to use one of the popular 3D printers from MakerBot, the cost of which starts at £ 1000, but they do not like adding tiny particles to the material. They work by squeezing a plastic thread, which then cools and solidifies, and the nanoparticles clog this system - especially if you add a lot of them to enhance the properties of the material.

Instead, we used the Asiga Pico 27 ​​plus at a price of £ 6,000. It uses digital light processing"and cures the plastic, illuminating it with ultraviolet light. The light is built up with 4000 micromirrors, similar to those used in home projectors. To make the model, the printer projects a set of two-dimensional images onto liquid plastic, and shifts the model slightly upward each time the layer is cured. Nanoparticles change the duration of illumination necessary for curing, and slightly absorb and scatter incident light, but taking this into account, printing can be done quite successfully.


One of the drawbacks of this technology is that it is not good at changing material types. Since the source material is liquid plastic, it must be kept in containers: the model is immersed in liquid when printing each next layer. To change the material, you have to stop everything and change the tanks manually, before printing the next layer.

This can be circumvented by leaving a hole in the model in place of another material. Then you can change materials and print inside this hole, resulting in a three-dimensional object with interconnected internal properties.

What will happen next


The technical problems of 3D printing of a working microphone are mainly related to the control of the process, the choice of the time of exposure to ultraviolet radiation with an accuracy of milliseconds and the careful combination and mixing of different materials. The end result is a device that behaves almost like a normal microphone, with the exception of the poor signal-to-noise ratio and the too-large resistance of the conductive layers. He, for example, can not be compared with a silicon microphone in your smartphone.


Our microphone

Other teams that tried printing with nanocomposite materials faced similar problems. In the manufacture of the optical components or accelerometers I mentioned, they usually tried to either embed pre-fabricated microchips and sensors into printed objects, or to correct plastic after printing. We have not yet reached the point where it will be possible, for example, to print a smartphone of decent quality from scratch: Samsung and Apple can still relax.



However, our present abilities still offer us amazing possibilities, in particular because good drives are easier to print than good sensors. Welcome to the emerging field of soft robotics , where there is the potential for gripping handsas soft and precise as human ones; or nanorobots, unpacked like origami, upon reaching the desired organ in the human body; or even whole robots, like fish by reference , able to imitate the complex movements of animals.

Prototypes of such devices already exist, although they combine printed and conventional components. After 10 years, most likely, it will be possible to print the whole. So, just like the characters of Star Trek from the 24th century, we will soon be able to select a file with some interesting device and print it to order. What do you say - soft robotic tentacle? Well, while for such things there are no mobile applications yet, but this is only a matter of time .

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