Normal-Direction Graded Hemispheres for Ionic Flexible Sensors with a Record-High Linearity in a Wide Working Range

Area of Science:

• Materials Science
• Nanotechnology
• Sensor Technology

Background:

• Flexible pressure sensors are crucial for wearable electronics but face challenges like nonlinearity and narrow working ranges due to inconsistent microstructure deformation.
• Existing sensors often exhibit reduced sensitivity and an insensitive response across their operational spectrum, limiting their application under high-pressure conditions.

Purpose of the Study:

• To develop an ionic flexible pressure sensor with ultrahigh linearity and a wide working range.
• To address the limitations of current sensors by introducing a novel microstructure design for consistent deformation.

Main Methods:

• Fabrication of flexible electrodes using poly(dimethylsiloxane) (PDMS)/carbon nanotubes (CNTs)/Au.
• Development of a normal-direction graded hemisphere (GH) microstructure.
• Design optimization using linear elastic theory and finite element simulation.

Main Results:

• Achieved record-high linearity (R² = 0.99994) over a wide working range up to 600 kPa.
• Demonstrated high sensitivity (S = 165.5 kPa⁻¹) and a fast response-relaxation time (<30 ms).
• Successfully applied the sensor to monitor underwater sports players' functional states by detecting vibration signals.

Conclusions:

• The graded hemisphere microstructure effectively ensures consistent deformation, leading to superior linearity in flexible pressure sensors.
• This work provides a theoretical and practical strategy for designing high-performance flexible pressure sensors with combined ultrahigh linearity, sensitivity, and wide working range.
• The developed sensor technology has potential applications in monitoring physiological signals and functional states in demanding environments.