Tactile multisensing on flexible aluminum nitride

Area of Science:

• Materials Science
• Nanotechnology
• Robotics

Background:

• Flexible tactile sensors are crucial for advanced robotic applications.
• Aluminum nitride (AlN) exhibits piezoelectric properties suitable for sensor development.
• Flexoelectricity in AlN can enhance transduction properties.

Purpose of the Study:

• To develop elastic tactile sensors using polycrystalline aluminum nitride (AlN) on a flexible substrate.
• To investigate the combined piezoelectric and capacitive responses of AlN under stress.
• To evaluate the flexoelectric effect's contribution to sensor performance.

Main Methods:

• Synthesized highly oriented polycrystalline AlN on Kapton HN using sputtering deposition.
• Characterized AlN crystal structure using X-ray diffraction and HRTEM.
• Fabricated parallel plate capacitors for tactile sensing and measured piezoelectric coefficient (d33) and stress-sensitive capacitance.

Main Results:

• Achieved high crystal orientation in AlN (FWHM = 0.55° of AlN (0002)).
• Measured piezoelectric coefficient d33 = 4.7 ± 0.5 pm V⁻¹ and stress-sensitive capacitance = 4 × 10⁻³ pF kPa⁻¹.
• Demonstrated sensor elasticity and sensitivity in the 10 kPa to 1 MPa range, with minimal capacitance shift (<0.02%) after bending.

Conclusions:

• Flexible AlN-based tactile sensors exhibit significant piezoelectric and capacitive variations under stress.
• The flexoelectric effect enhances the transduction properties of AlN.
• The developed sensors are suitable for robotic applications due to their elasticity, sensitivity, and robustness to bending.