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

This ink is made for wearing.
Nergis Firtina

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.

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

What is the difference?

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.

Newly 3D print-produced ink may be used as a tattoo, study says
Bioink for 3D-printable wearable bioelectronics.

They might be used in the tattoo

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.

“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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