Pencetakan 4D:Masa Depan pencetakan 3D

Bagaimana jika pipa dapat memperbaiki dirinya sendiri secara otomatis jika retak atau pecah, atau pakaian dapat berubah sesuai dengan cuaca atau aktivitas yang dilakukan pengguna ? Perabotan yang merakit dirinya sendiri, prostesis yang beradaptasi dengan pertumbuhan... Ini hanyalah beberapa kemungkinan aplikasi yang diharapkan dapat diwujudkan oleh teknologi pencetakan 4D.

Gambar 1:Capit cetakan 4D yang memodifikasi bentuknya. Sumber:Sculpteo.

Pencetakan 3D telah ada selama hampir 30 tahun dan saat masih dalam proses penelitian, menemukan materi dan aplikasi baru, teknologi baru seperti 4D telah muncul.

Di Lab Perakitan Mandiri MIT , mereka telah mengembangkan proyek di mana pencetakan 4D menjadi bagiannya. Tujuannya adalah menggabungkan teknologi dan desain untuk menciptakan materi yang dapat diprogram dan teknologi perakitan sendiri dengan tujuan menemukan kembali konstruksi, manufaktur, perakitan produk, dan kinerja. Sementara itu, penelitian olehWyss Institute (bagian dari Universitas Harvard) telah berhasil mencetak sebuah benda yang jika terkena air akan berubah bentuk e, menghasilkan semacam pembungaan pada ujungnya. Mereka mengembangkan bahan berdasarkan struktur alami, seperti tumbuhan, yang disuntik dengan serat selulosa selama proses pencetakan.

Video 1:Arsitektur yang mengubah bentuk. Sumber:Universitas Harvard.

Apa itu pencetakan 4D?

Terinspirasi oleh prinsip perakitan mandiri, pencetakan 4D adalah proses di mana objek cetakan 3D diubah menjadi struktur berbeda dengan pengaruh masukan energi eksternal seperti suhu, cahaya, atau rangsangan lingkungan lainnya. Artinya, memperoleh objek melalui teknologi 3D yang, berkat sifat bahan pembuatnya, dapat berubah saat terkena rangsangan lingkungan.

Inilah perbedaannya antara teknologi 3D dan 4D:kemampuan objek untuk berubah dari waktu ke waktu tanpa campur tangan manusia.

Bahan yang digunakan

Kunci untuk pencetakan 4D bukan pada prosesnya , berdasarkan printer 3D yang sudah dikenal,tetapi bahannya. Karena ini adalah teknologi yang cukup baru, bahan yang tersedia tidak beragam seperti yang digunakan untuk pencetakan 3D standar. Namun, ada beberapa yang sangat menarik.

SMP (polimer memori bentuk)

Polimer yang tetap kaku pada suhu kamar dan menawarkan sifat khusus saat mencapai titik transisi kaca. Contohnya adalah SMP TPU Convena:filamen 4D dengan komposisi berdasarkan TPU (poliuretan termoplastik) yang memungkinkan pasca-pemrosesan mengubah bentuk komponen cetak 3D. Berkat komposisi khusus dan teknologi Shape Memory Polymer, parts printed with this filament can be modified manually, allowing them to acquire another shape and maintain it over time.

The process of modifying the shape of a 3D printed part with SMP TPU filament consists of placing the 3D printed part in a container of hot water until it reaches its glass transition temperature. At this point, the part softens and the user can easily modify its shape. Once cooled, the part maintains the acquired shape and remains stable. In addition, parts 3D printed with SMP TPU filament can be restored to their original shape by reversing the process. In other words, the material's glass transition temperature is reached again.

LCE (liquid crystal elastomers)

They contain liquid crystals that are sensitive to heat. By controlling their orientation, the desired shape can be programmed: under the effect of temperature, the material will relax and transform according to the dictated code.

Hydrogels

Polymer chains consisting mainly of water , particularly used in light-curing processes. The latter are focused on the medical sector due to their biocompatibility.

In addition, some 4D printing processes can use various materials, mainly composites such as wood or carbon, which are added to SMP or hydrogels. This results in objects with rigid and movable areas.

Applications

Given the many advantages of such intelligent materials, the applications of 4D printing are innumerable.

Construction

The construction of climate-adapted structures such as bridges, shelters or other facilities would be a huge step forward in this field. 4D bricks capable of modifying walls and roofs to suit the environment would allow indoor conditions to be modified and improved.

Video 2:Programmable wood. Source:Self-Assembly Lab, MIT.

Medicine

In this case, 4D printing offers the possibility to create tailor-made, intelligent and evolving devices. For example, by 4D printing an implant, its condition and viability could be more easily monitored once it is integrated into the patient.

This concept is applicable to all regenerative medicine and the fabrication of cellular structures. 4D printing would allow cells to adapt to the human body depending on its temperature, for example. If we talk about medicines, it would be possible, for example, to print a device that would release the required dose depending on the patient's body temperature.

Transport

A few months ago, BMW and MIT presented their inflatable material, which changes shape and size under the effect of air pulses. The applications are very interesting, as in the future we could have tyres that can repair themselves in case of a puncture or adapt to the terrain and weather conditions of the environment.

In the case of the aircraft industry, a 4D printed component could react to atmospheric pressure or temperature changes and thus change its function. Airbus is currently working on such developments, as these components could replace hinges and hydraulic actuators, significantly lightening the devices . In addition, it is also working on the development of heat-reactive materials to cool its aircraft engines.

Raúl Pulido Casillas, a Spanish engineer, has created a 4D-printed smart fabric for NASA. The metallic mesh, made of silver pieces joined together, has thermal regulation programmed into its print. In other words, not only its shape has been printed, but also the function of the materials. As it is able to reflect heat on the outside and retain it on the inside, it could be an ideal element for making astronaut suits or covering spacecraft.

Fashion

In the textile industry, 4D printing is also finding its place. The possibility of printing shoes that adapt to movement, impact, temperature and atmospheric pressure is a possibility. The US military has already made a foray into this field and is testing uniforms that change colour depending on the environment, or that regulate perspiration depending on the soldier's pulse or the ambient temperature.

Although we are still in its infancy, it is certain that 4D technology will revolutionise the manufacture and nature of objects over the next few years, just as 3D printing did in its day.