Flexible electronics has enabled the design of sensors, actuators, microfluidics, and electronics in flexible, conformable, and/or stretchable sublayers for wearable, implantable, or ingestible applications. However, these devices have very different biological and mechanical properties compared to human tissue and therefore cannot integrate with the human body.
A team of researchers at Texas A&M University has developed a new class of biomaterial inks that mimic the native characteristics of highly conductive human tissue, such as skin, that are essential for the ink to be used in 3D printing.
This biomaterial ink harnesses a new class of 2D nanomaterials known as molybdenum disulfide (MoStwo). The thin layer structure of MoStwo it contains defective centers to make it chemically active and, combined with modified gelatin to obtain a flexible hydrogel, comparable to the structure of Jell-O.
“The impact of this work is far-reaching on 3D printing,” said Dr. Akhilesh Gaharwar, Associate Professor in the Department of Biomedical Engineering and Presidential Impact Fellow. “This newly designed hydrogel ink is highly biocompatible and electrically conductive, paving the way for the next generation of wearable and implantable bioelectronics.”
This study was recently published in DHW Nano.
The ink has shear thinning properties that decrease in viscosity as force increases, so it is solid inside the tube but flows more like a liquid when squeezed, similar to ketchup or toothpaste. The team embedded these electrically conductive nanomaterials inside a modified gelatin to make a hydrogel ink with characteristics that are essential for ink design conducive to 3D printing.
“These 3D-printed devices are extremely elastomeric and can be compressed, bent or twisted without breaking,” said Kaivalya Deo, a graduate student in the department of biomedical engineering and lead author of the paper. “In addition, these devices are electronically active, allowing them to monitor dynamic human motion and paving the way for continuous motion monitoring.”
To print the ink in 3D, researchers at the Gaharwar Laboratory designed a cost-effective, open source, multi-head 3D bioprinter that is fully functional and customizable, running on open source tools and free software. This also allows any researcher to build 3D bioprinters tailored to their own research needs.
The electrically conductive 3D-printed hydrogel ink can create complex 3D circuits and is not limited to flat designs, allowing researchers to create customizable bioelectronics tailored to specific patient requirements.
By using these 3D printers, Deo was able to print stretchable, electrically active electronic devices. These devices demonstrate outstanding voltage sensing capabilities and can be used to design customizable monitoring systems. This also opens up new possibilities for designing extensible sensors with embedded microelectronic components.
One of the possible applications of the new ink is the 3D printing of electronic tattoos for patients with Parkinson’s disease. The researchers envision that this printed electronic tattoo could monitor a patient’s movement, including tremors.
This project is in collaboration with Dr. Anthony Guiseppi-Elie, Vice President for Academic Affairs and Workforce Development at Tri-County Technical College, and Dr. Limei Tian, Assistant Professor of Biomedical Engineering at Texas A&M.
This study was funded by the National Institute for Biomedical Imaging and Bioengineering, the National Institute of Neurological Disorders and Stroke, and the Texas A&M University President’s Fund of Excellence. A provisional patent on this technology has been filed in association with the Texas A&M Engineering Experiment Station.
Materials provided by Texas A&M University. Original written by Alleynah Veatch Cofas. Note: content can be edited for style and length.