In Situ Formation of Conductive Epidermal Electrodes Using a Fully Integrated Flexible System and Injectable Photocurable Ink

Abstract

In situ fabrication of wearable devices through coating approaches is a promising solution for the fast deployment of wearable devices and more adaptable devices for different sensing demands. However, heat, solvent, and mechanical sensitivity of biological tissues, along with personal compliance, pose strict requirements for coating materials and methods. To address this, a biocompatible and biodegradable light-curable conductive ink and an all-in-one flexible system that conducts in situ injection and photonic curing of the ink as well as monitoring of biophysiological information have been developed. The ink can be solidified through spontaneous phase changes and photonic cured to achieve a high mechanical strength of 7.48 MPa and an excellent electrical conductivity of 3.57 × 10 5 S/m. The flexible system contains elastic injection chambers embedded with specially designed optical waveguides to uniformly dissipate visible LED light throughout the chambers and rapidly cure the ink in 5 min. The resulting conductive electrodes offer intimate skin contact even with the existence of hair and work stably even under an acceleration of 8 g, leading to a robust wearable system capable of working under intense motion, heavy sweating, and varied surface morphology. Similar concepts may lead to various rapidly deployable wearable systems that offer excellent adaptability to different monitoring demands for the health tracking of large populations.

A 10-micrometer-thick nanomesh-reinforced gas-permeable hydrogel skin sensor for long-term electrophysiological monitoring

“…S27). The above results suggest great potentiality of the ultrathin hydrogels for early diagnosis of cardiac disorders, such as bundle branch block and Brugada syndrome ( 55 ).…”

E-Tattoos: Toward Functional but Imperceptible Interfacing with Human Skin

“…Biological tissues, which are sensitive to heat, solvent, mechanical forces, and compliance, require a fast curing process for the printed ink. Wan et al recently developed a flexible 3D printing system with an elastic injection chamber containing embedded LEDs . These LEDS emit light that penetrates through the ink for fast curing, reducing the curing time to a rapid period of 5 min.…”

Light‐Mediated Polymerization Catalyzed by Carbon Nanomaterials

“…Light‐mediated polymerization has received increasing interest in polymer synthesis for use in diverse fields [1–19] . Examples include, but not limited to lithography, [4,9,20–22] printing based on 2D, [4,15,23,24] 3D [4,6,8,25–52] or 4D [27–29,53,54] patterning, holographic recording, [16,55,56] fabrication of prosthesis, [57] dental composites, [38,46,58] anti‐counterfeiting materials, [59] inks, [4,60,61] surface modification of solidified coatings [4,13,14,62–68] or adhesives [4,69–72] . Formulating of light‐sensitive compositions based on Chemistry 4.0, which was defined by the VCI in Germany as a combination of artificial intelligence (AI) and central data management, [73] can be seen as an additional challenging aspect [18] .…”