Mechanically Interlocked Hydrogel-Elastomer Strain Sensor with Robust Interface and Enhanced Water-Retention...

Area of Science:

• Materials Science
• Polymer Science
• Wearable Technology

Background:

• Hydrogels are ion conductors suitable for strain sensors but prone to dehydration.
• Dehydration compromises hydrogel flexibility and functionality, limiting their practical applications.
• Existing solutions for hydrogel water retention are often complex or inefficient.

Purpose of the Study:

• To develop a robust strategy for preventing hydrogel dehydration.
• To enhance the mechanical properties and interfacial adhesion of hydrogel-based sensors.
• To demonstrate the efficacy of a novel encapsulated hydrogel strain sensor for real-world applications.

Main Methods:

• Encapsulating hydrogels within a hydrophobic polydimethylsiloxane (PDMS) elastomer shell.
• Utilizing a porous thermoplastic polyurethane (TPU) interlayer for strong hydrogel-elastomer adhesion.
• Fabricating and testing an ionic hydrogel strain sensor with the proposed encapsulation strategy.

Main Results:

• The PDMS encapsulation significantly reduced water evaporation (4.6 wt.% ± 0.57 loss in 24 h).
• The TPU interlayer achieved high interfacial toughness (>1200 J/m²), ensuring robust bonding.
• The encapsulated sensor exhibited excellent water retention, superior mechanical performance, and high linear sensitivity (gauge factor = 2.21 at 100% strain).

Conclusions:

• The hydrophobic elastomer encapsulation is an effective method for preserving hydrogel properties.
• The developed hydrogel-elastomer hybrid sensor demonstrates high performance and durability.
• This technology shows great potential for practical applications in human motion monitoring and wearable devices.