A Flexible Piezoresistive Sponge Sensor with a Dual-Scale Porous Structure for Ultra-Wide-Range and High-Sensitivity...

Area of Science:

• Materials Science
• Nanotechnology
• Sensor Technology

Background:

• Flexible piezoresistive sensors are crucial for wearable electronics.
• A key challenge is achieving high sensitivity and a wide sensing range simultaneously.
• Existing sensors often compromise one performance metric for the other.

Purpose of the Study:

• To develop a flexible piezoresistive sponge sensor that overcomes the sensitivity-detection range trade-off.
• To create a hierarchical porous structure for enhanced sensor performance.
• To demonstrate the sensor's potential in multimodal sensing and human-machine interaction.

Main Methods:

• Fabrication of a macroscale porous sponge matrix using multiwalled carbon nanotubes (MWCNTs)/polydimethylsiloxane (PDMS) with NaCl sacrificial templates.
• Creation of a microscale porous conductive coating using MWCNTs/carboxymethyl cellulose (CMC) on the sponge skeleton.
• Characterization of the dual-scale porous structure and its impact on sensor performance.

Main Results:

• The sensor achieved an ultrawide sensing range from 10 Pa to 4.3 MPa.
• High peak sensitivity of 33.890 kPa^-1 was recorded within the 10 Pa-40 kPa range.
• Exceptional durability was demonstrated over 4100 cycles at 1 MPa with minimal degradation.
• Successful multimodal sensing of physiological signals and extreme mechanical stresses was achieved.
• A human-machine interaction system utilizing the sensors for robotic hand control was developed.

Conclusions:

• The dual-scale porous structure offers a universal strategy to overcome the sensitivity-detection range limitations in flexible piezoresistive sensors.
• This innovative design redefines the capabilities of such sensors.
• The developed sensor shows significant potential for human-motion monitoring and interactive human-machine systems.