A Biodegradable and Stretchable Protein-Based Sensor as Artificial Electronic Skin for Human Motion Detection

Area of Science:

• Biomaterials Science
• Materials Engineering
• Wearable Electronics

Background:

• Silk fibroin (SF) offers biodegradability and biocompatibility, making it suitable for electronic devices.
• Challenges in SF-based electronics include brittleness and water solubility, hindering traditional fabrication.
• Existing SF electronics lack the flexibility and durability required for advanced applications.

Purpose of the Study:

• To develop a flexible and stretchable electrode using silk fibroin (SF) and silver nanofibers (Ag NFs).
• To create a tactile sensor capable of simultaneously detecting pressure and strain signals.
• To enable long-term, skin-compatible health monitoring through air-permeable and inflammation-free sensor technology.

Main Methods:

• Synthesis of a silver nanofibers (Ag NFs)/SF based electrode using water-free procedures.
• Fabrication of a flexible and tactile sensor utilizing the developed Ag NFs/SF electrode.
• Characterization of electrode performance including sheet resistance, transmittance, stability, and extensibility.
• Evaluation of sensor capabilities for simultaneous pressure and strain detection and skin adhesion.

Main Results:

• The Ag NFs/SF electrode exhibited low sheet resistance (10.5 Ω sq⁻¹), high transmittance (>90%), and excellent stability (>2200 bending cycles).
• The electrode demonstrated good extensibility (>60% stretching).
• The fabricated sensor successfully detected pressure (35 Pa-700 kPa) and strain signals simultaneously, showing air-permeability and inflammation-free properties.

Conclusions:

• The developed water-free synthesized Ag NFs/SF electrode overcomes SF's limitations, offering superior flexibility and durability.
• The resulting tactile sensor is suitable for direct skin lamination, enabling long-term health monitoring.
• This biodegradable and skin-comfortable sensor shows promise for on-skin and implantable health-monitoring devices.