Trap Assisted Dynamic Mechanoluminescence Toward Self-Referencing and Visualized Strain Sensing

Area of Science:

• Materials Science
• Solid State Physics
• Optoelectronics

Background:

• Mechanoluminescent (ML) materials offer self-powering, non-contact strain sensing.
• Current ML strain sensing relies on intensity-strain relationships vulnerable to environmental factors.
• Developing robust, self-referencing ML strain sensors is crucial for reliable measurements.

Purpose of the Study:

• To investigate a color-resolved, visualized, dynamic ML and self-referencing strain sensing method.
• To establish a relationship between strain and the ML intensity ratio of Tb³⁺/Mn²⁺ in Ca₉Al(PO₄)₇.
• To enable visualized strain sensing technology independent of absolute ML intensity.

Main Methods:

• Synthesized and characterized Ca₉Al(PO₄)₇: Tb³⁺, Mn²⁺ for ML properties.
• Analyzed ML intensity ratios under various mechanical stimulations (stretching).
• Compared luminescence under mechanical and X-ray irradiation to understand carrier dynamics.

Main Results:

• Established a strain-dependent ML intensity ratio (Tb³⁺/Mn²⁺) for self-referencing.
• Demonstrated that ratiometric ML is driven by carrier dynamics in traps, compensating for Mn²⁺ emission.
• Achieved color-resolved visualization of strain (green to red).

Conclusions:

• Developed a self-referencing, visualized strain sensor overcoming environmental interference.
• The ratiometric approach using Tb³⁺/Mn²⁺ provides a stable measure of strain.
• Successfully demonstrated application in monitoring human joint movement, highlighting potential in human-machine interaction.