Perfectly Spatial and Shape-Controllable Nanocrack Lithography via Localized Compressive-Shear Stress Coupling.

Area of Science:

• Materials Science and Engineering
• Nanotechnology
• Mechanical Engineering

Background:

• Cracking-assisted nanofabrication is valuable for creating nanoscale features due to its simplicity and cost-effectiveness.
• Conventional methods lack control over nanocrack density, shape, and uniformity, stemming from random stress concentrations and uncontrolled stress distribution.
• Defects in materials and uncontrolled mechanical stress hinder precise nanocrack formation in current techniques.

Purpose of the Study:

• To develop a reliable and reproducible nanocrack patterning method for large-scale, customizable patterns on flexible substrates.
• To overcome the limitations of conventional methods in controlling nanocrack characteristics.
• To demonstrate the application of the novel method in functional materials and devices.

Main Methods:

• Utilized photolithography to create microphotoresist structures on flexible substrates.
• Applied simultaneous bending and pressing to induce compressive-shear stress coupling.
• Localized stress at structure corners to facilitate controlled nanocrack formation.

Main Results:

• Achieved precise spatial and shape control of nanocrack patterns in functional materials.
• Demonstrated uniform nanocrack spacing (40 μm ± 0.1 μm) in platinum films on polymer substrates.
• Successfully patterned diverse shapes (zigzag, wave, square, circle) in copper thin films and applied to strain sensors, pressure sensors, and transparent flexible substrates.

Conclusions:

• The developed method offers high reliability and reproducibility for nanocrack patterning on flexible substrates.
• The technique enables precise control over nanocrack characteristics, suitable for various functional materials.
• The method has demonstrated efficacy in fabricating functional devices like high-performance strain sensors and 3D pressure sensors.