3D printing tattoos

Engineers 3-D print a “living tattoo” | MIT News

MIT engineers have devised a 3-D printing technique that uses a new kind of ink made from genetically programmed living cells.

The cells are engineered to light up in response to a variety of stimuli. When mixed with a slurry of hydrogel and nutrients, the cells can be printed, layer by layer, to form three-dimensional, interactive structures and devices.

The team has then demonstrated its technique by printing a “living tattoo” — a thin, transparent patch patterned with live bacteria cells in the shape of a tree. Each branch of the tree is lined with cells sensitive to a different chemical or molecular compound. When the patch is adhered to skin that has been exposed to the same compounds, corresponding regions of the tree light up in response.

The researchers, led by Xuanhe Zhao, the Noyce Career Development Professor in MIT’s Department of Mechanical Engineering, and Timothy Lu, associate professor of biological engineering and of electrical engineering and computer science, say that their technique can be used to fabricate “active” materials for wearable sensors and interactive displays. Such materials can be patterned with live cells engineered to sense environmental chemicals and pollutants as well as changes in pH and temperature.

What’s more, the team developed a model to predict the interactions between cells within a given 3-D-printed structure, under a variety of conditions. The team says researchers can use the model as a guide in designing responsive living materials.

Zhao, Lu, and their colleagues have published their results today in the journal Advanced Materials. The paper’s co-authors are graduate students Xinyue Liu, Hyunwoo Yuk, Shaoting Lin, German Alberto Parada, Tzu-Chieh Tang, Eléonore Tham, and postdoc Cesar de la Fuente-Nunez.

A hardy alternative

In recent years, scientists have explored a variety of responsive materials as the basis for 3D-printed inks. For instance, scientists have used inks made from temperature-sensitive polymers to print heat-responsive shape-shifting objects. Others have printed photoactivated structures from polymers that shrink and stretch in response to light.  

Zhao’s team, working with bioengineers in Lu’s lab, realized that live cells might also serve as responsive materials for 3D-printed inks, particularly as they can be genetically engineered to respond to a variety of stimuli. The researchers are not the first to consider 3-D printing genetically engineered cells; others have attempted to do so using live mammalian cells, but with little success.

“It turns out those cells were dying during the printing process, because mammalian cells are basically lipid bilayer balloons,” Yuk says. “They are too weak, and they easily rupture.”

Instead, the team identified a hardier cell type in bacteria. Bacterial cells have tough cell walls that are able to survive relatively harsh conditions, such as the forces applied to ink as it is pushed through a printer’s nozzle. Furthermore, bacteria, unlike mammalian cells, are compatible with most hydrogels — gel-like materials that are made from a mix of mostly water and a bit of polymer. The group found that hydrogels can provide an aqueous environment that can support living bacteria.

The researchers carried out a screening test to identify the type of hydrogel that would best host bacterial cells. After an extensive search, a hydrogel with pluronic acid was found to be the most compatible material. The hydrogel also exhibited an ideal consistency for 3-D printing.

“This hydrogel has ideal flow characteristics for printing through a nozzle,” Zhao says. “It’s like squeezing out toothpaste. You need [the ink] to flow out of a nozzle like toothpaste, and it can maintain its shape after it’s printed.”

From tattoos to living computers

Lu provided the team with bacterial cells engineered to light up in response to a variety of chemical stimuli. The researchers then came up with a recipe for their 3-D ink, using a combination of bacteria, hydrogel, and nutrients to sustain the cells and maintain their functionality.

“We found this new ink formula works very well and can print at a high resolution of about 30 micrometers per feature,” Zhao says. “That means each line we print contains only a few cells. We can also print relatively large-scale structures, measuring several centimeters.”

They printed the ink using a custom 3-D printer that they built using standard elements combined with fixtures they machined themselves. To demonstrate the technique, the team printed a pattern of hydrogel with cells in the shape of a tree on an elastomer layer. After printing, they solidified, or cured, the patch by exposing it to ultraviolet radiation. They then adhere the transparent elastomer layer with the living patterns on it, to skin.

To test the patch, the researchers smeared several chemical compounds onto the back of a test subject’s hand, then pressed the hydrogel patch over the exposed skin. Over several hours, branches of the patch’s tree lit up when bacteria sensed their corresponding chemical stimuli.

The researchers also engineered bacteria to communicate with each other; for instance they programmed some cells to light up only when they receive a certain signal from another cell. To test this type of communication in a 3-D structure, they printed a thin sheet of hydrogel filaments with “input,” or signal-producing bacteria and chemicals, overlaid with another layer of filaments of an “output,” or signal-receiving bacteria. They found the output filaments lit up only when they overlapped and received input signals from corresponding bacteria .

Yuk says in the future, researchers may use the team’s technique to print “living computers” — structures with multiple types of cells that communicate with each other, passing signals back and forth, much like transistors on a microchip.

“This is very future work, but we expect to be able to print living computational platforms that could be wearable,” Yuk says.

For more near-term applications, the researchers are aiming to fabricate customized sensors, in the form of flexible patches and stickers that could be engineered to detect a variety of chemical and molecular compounds. They also envision their technique may be used to manufacture drug capsules and surgical implants, containing cells engineered produce compounds such as glucose, to be released therapeutically over time.

“We can use bacterial cells like workers in a 3-D factory,” Liu says. “They can be engineered to produce drugs within a 3-D scaffold, and applications should not be confined to epidermal devices. As long as the fabrication method and approach are viable, applications such as implants and ingestibles should be possible.”

This research was supported, in part, by the Office of Naval Research, National Science Foundation, National Institutes of Health, and MIT Institute for Soldier Nanotechnologies.

Newly 3D print-produced ink may be used as a tattoo, study says

Flexible electronics have been used in many fields, from sensors, actuators, microfluidics, and electronics. They can be flexible, compliant, extensible substrates for wearability to implantable or ingestible applications, but due to the substances they contain, it was not possible to integrate them into the human body.

However, a team of researchers from Texas A&M University has developed a new class of biomaterial inks with 3D printing that mimic human tissue, just like skin.

The study was recently published in ACS Nano.

As per the study, newly produced biomaterial ink leverages a new class of 2D nanomaterials known as molybdenum disulfide (MoS2). This thin-layered structure of Mo32 involves defect centers to make it chemically active and, combined with modified gelatin to obtain a flexible hydrogel, is comparable to the structure of Jell-O.

Akhilesh Gaharwar

Texas A&M Engineering

“The impact of this work is far-reaching in 3D printing,” said Akhilesh Gaharwar, associate professor in the Department of Biomedical Engineering and Presidential Impact Fellow.

“This newly developed hydrogel ink is highly biocompatible and electrically conductive, paving the way for the next generation of wearable and implantable bioelectronics,” he said.

Researchers amalgamated electrically conductive nanomaterials within modified gelatin to make a hydrogel ink which is required for designing ink conducive to 3D printing.

Normally, ink has shear-thinning properties that decrease in viscosity as force increases. For this reason, even though it stays in a solid state in a tube, it turns into a liquid when it comes out.

Bioink for 3D-printable wearable bioelectronics.

Gaharwar Laboratory/Texas A&M University  

Based on the results of the research, we see that this newly produced 3D ink is wearable, and for this reason, it is believed that Parkinson's patients, for example, can be injected under their skin to facilitate their monitoring.

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“These 3D-printed devices are extremely elastomeric and can be compressed, bent, or twisted without breaking,” said Kaivalya Deo, a graduate student in the biomedical engineering department and lead author of the paper. “In addition, these devices are electronically active, enabling them to monitor dynamic human motion and paving the way for continuous motion monitoring,” he also told.

This project is in collaboration with Dr. Anthony Guiseppi-Elie, vice president of academic affairs and workforce development at Tri-County Technical College in South Carolina, and Dr. Limei Tian, assistant professor of biomedical engineering at Texas A&M.

This study was funded by the National Institute of Biomedical Imaging and Bioengineering, the National Institute of Neurological Disorders and Stroke, and the Texas A&M University President’s Excellence Fund. A provisional patent on this technology has been filed in association with the Texas A&M Engineering Experiment Station.

Study abstract:

Flexible electronics require elastomeric and conductive biointerfaces with native tissue-like mechanical properties. The conventional approaches to engineer such a biointerface often utilize conductive nanomaterials in combination with polymeric hydrogels that are cross-linked using toxic photoinitiators. Moreover, these systems frequently demonstrate poor biocompatibility and face trade-offs between conductivity and mechanical stiffness under physiological conditions. To address these challenges, we developed a class of shear-thinning hydrogels as biomaterial inks for 3D printing flexible bioelectronics. These hydrogels are engineered through a facile vacancy-driven gelation of MoS2 nanoassemblies with naturally derived polymer-thiolated gelatin. Due to shear-thinning properties, these nanoengineered hydrogels can be printed into complex shapes that can respond to mechanical deformation. The chemically cross-linked nanoengineered hydrogels demonstrate a 20-fold rise in compressive moduli and can withstand up to 80% strain without permanent deformation, meeting human anatomical flexibility. The nanoengineered network exhibits high conductivity, compressive modulus, pseudocapacitance, and biocompatibility. The 3D-printed cross-linked structure demonstrates excellent strain sensitivity and can be used as wearable electronics to detect various motion dynamics. Overall, the results suggest that these nanoengineered hydrogels offer improved mechanical, electronic, and biological characteristics for various emerging biomedical applications including 3D-printed flexible biosensors, actuators, optoelectronics, and therapeutic delivery devices.

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3D printer - tattoo machine! A new page in the history of 3D technologies.

An original 3D printer-tattoo machine has been created

The relative novelty of 3D printing technology leads to its many unique applications in various fields. Obviously, too little time has passed for a complete transformation of the methodology, since society has not had time to fully master the existing methods of additive manufacturing. However, the bright minds of mankind are constantly working on the development and improvement of 3D printing technology. And sometimes this leads to very unexpected results. In each case, the technique itself is directly involved, or rather, special equipment for it. But what happens if we discard all unnecessary and leave only the principle of operation of a 3D printer? We have a great example: a 3D printer - a tattoo machine. nine0005

Back in 2014, a group of enthusiasts from France set an extravagant goal: to combine a 3D printer with a tattoo machine and actively began to implement their idea. Thus was born an unusual invention that fully performs its functions with some limitations. In 2015, the developers presented their creation to the world, which by that time was able to draw a picture on a human hand well fixed in the body. From such a blank, a 3D printer developed - a tattoo machine. nine0005

Of course, the French did not stop there and boldly continued experiments on an amazing device. One of the main intentions of the developers was to adapt the mechanism for applying a tattoo to any part of the body, and now, after some time, they found an original way to solve this problem.

3D printer - tattoo machine: features of

But before we get to it, we will tell you a little about the process of creating the first sample. To make a 3D tattoo machine, the developers removed the extruder from the MakerBot 3D printer and replaced it with a tattoo needle. The next step was to equip the device with special sensors that scan the surface of the user's skin, on the basis of which the device adapts to the size and structure of the skin of the limb, which significantly increases the accuracy of drawing the pattern. nine0005

In the course of work, the creators had to face a number of difficulties, since a 3D printer in the traditional sense is not adapted to perform its functions on such an atypical surface. The need to follow the curves of the human body led the French to delve into robotics, which led them to another interesting idea.

With the help of an industrial robot and 3D scanning technology, they could get the information needed to program a mechanical arm to tattoo a human body. Since the task turned out to be entirely feasible, the developers immediately took up its implementation, in which they were greatly facilitated by the conclusion of cooperation with the notorious company Autodesk. nine0005

Highlights of the 3D Printer - Tattoo Machine

As David Thomasson, an engineer at the latter's research lab, points out, “Our research is really focused on a closer interaction between man and machine, which will most certainly be achieved in the near future. With this project, we are moving almost to the limit. In fact, all developed devices imply complete separation from humans. It's completely new territory."

Finally, after much experimentation and countless 3D scan data, the device was completed. The 3D printer-tattoo machine has been successfully tested and is fully ready for its intended use. It looks like this is really a completely new page in the history of 3D technology. nine0005

https://vimeo.com/175491863

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Always dreamed of getting a tattoo? Now the 3D printer