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3D printing of electronic skins brings new progress to human-computer interaction

2024-01-31 15:11

Human skin has over 1000 nerve endings, making it the largest sensory connection between the brain and the outside world, providing rich feedback through touch, temperature, and pressure. Although these complex features make the skin an important organ, they also bring replication challenges.

On January 29, 2024, researchers at Texas A&M University (TAMU) successfully developed a 3D printed electronic skin (E-skin) using nano engineered hydrogels with adjustable electronic and thermal biosensing capabilities. This type of electronic skin can bend and stretch freely like human skin, and has perceptual functions. Dr. Akhilesh Gaharwar, Professor and Research Director of the Department of Biomedical Engineering, said, "The ability to replicate touch and integrate it into various technologies opens up new possibilities for human-computer interaction and advanced sensory experiences, which is expected to fundamentally change the industry and improve the quality of life for people with disabilities."
The main authors of this paper are Kaivalya Deo, a former student of Dr. Gaharwar and current scientist at Axent Biosciences, as well as Shounak Roy, a former Dr. Fulbright Nehru researcher at Gaharwar Lab.

Imitation of human skin lacks sufficient elasticity and softness
The manufacturing of electronic skins faces a challenge of developing materials that are both durable and mimic the flexibility of human skin, include bioelectric sensing functions, and are suitable for wearable or implantable devices. "In the past, the stiffness of these systems was too high for our body tissues, hindering signal transduction and causing mechanical mismatch at the biotic abiotic interface," said Deo. Researchers have successfully solved one of the key limitations in the field of flexible bioelectronics by introducing a "triple crosslinking" strategy in hydrogel based systems

(The conductivity of nano engineering hydrogels and their application as electronic skin for dynamic sensing of strain and pressure)

 

The use of nano engineering hydrogels has solved some challenges in the process of 3D printing electronic skin. Hydrogel can reduce viscosity under shear stress during the creation process of electronic skin, making it easier to handle and operate. The team stated that this feature helps to construct complex 2D and 3D electronic structures, which is an important aspect of replicating the multifaceted nature of human skin.

Researchers also utilized the "atomic defects" in molybdenum disulfide nanocomponents (a material with defects in its atomic structure that can achieve high conductivity) and polydopamine nanoparticles to help electronic skin adhere to wet tissue.

(Physical and chemical characterization of cross-linked Pul SH/PDA/MoS2 hydrogels)

Roy explained, "These specially designed molybdenum disulfide nanoparticles act as crosslinking agents, forming a hydrogel and endowing electronic skin with conductivity and thermal conductivity. We are the first to report using it as a key component, and the ability of this material to adhere to wet tissue is particularly important for potential medical and healthcare applications, as electronic skin needs to adapt and adhere to dynamic, moist biological surfaces."
Other collaborators include researchers from Dr. Limei Tian's team in the Department of Biomedical Engineering at Texas A&M University and Dr. Amit Jaiswal from Mandy Institute of Technology in India. The future application fields of electronic skin are very extensive, including wearable health devices that can continuously monitor vital signs such as exercise, body temperature, heart rate, and blood pressure. These devices will provide feedback to users and assist them in improving their motor skills and coordination.