An In Situ Assembled, Sprayable Poly(Lipoic Acid) E-Tattoo for Multimodal Health Monitoring

Area of Science:

• Materials Science
• Biomedical Engineering
• Wearable Electronics

Background:

• Electronic skins (e-skins) offer personalized healthcare potential due to skin conformability.
• Current e-skins face challenges in fabrication complexity, conformability, and biocompatibility.

Purpose of the Study:

• To develop a novel, sprayable electronic tattoo (LS e-tattoo) for improved e-skin applications.
• To overcome limitations of existing e-skins through rapid, in-situ fabrication and enhanced biocompatibility.

Main Methods:

• Formulation of a poly(lipoic acid)-based sprayable ink with lipoic acid (LA), tannic acid (TA), and silver flakes.
• Utilizing spray-coating for polymerization and Zn2+ spray for curing to form an in-situ conductive network on the skin.
• Development of an integrated epidermal sensing system for simultaneous physiological monitoring.

Main Results:

• The LS e-tattoo demonstrated rapid (3 min), conformal, breathable, and biocompatible network formation.
• Achieved ultralow contact impedance (95 kΩ at 50 Hz) and exceptional mechanical robustness ( < 1% resistance change after 1,500 bending cycles).
• Enabled synchronous detection of sweat chloride (R2 = 0.992), body temperature (error < 0.1°C), skin hydration (R2 = 0.998), and high-fidelity electromyography signals (SNR: 14.4 dB).

Conclusions:

• The sprayable LS e-tattoo offers a versatile platform for customized e-skins with rapid, on-demand fabrication and conformal integration.
• This technology advances personalized healthcare through simultaneous, high-fidelity epidermal sensing.
• The developed e-tattoo addresses key limitations in current wearable electronic technologies.