Controlled 3D buckling of silicon nanowires for stretchable electronics

Area of Science:

• Materials Science
• Nanotechnology
• Mechanical Engineering

Background:

• Stretchable electronics require materials that can withstand significant deformation.
• Silicon nanowires (NWs) offer unique electronic properties but typically lack stretchability.
• Controlled fabrication of nanostructures on flexible substrates is crucial for advanced applications.

Purpose of the Study:

• To develop a method for fabricating stretchable silicon nanowire (Si NW) coils.
• To investigate the mechanical properties and stretchability of these Si NW coils.
• To demonstrate the potential of Si NW coils for applications in stretchable electronics.

Main Methods:

• Fabrication of Si NW coils on elastomeric poly(dimethylsiloxane) (PDMS) substrates via a controlled buckling process.
• Utilizing prestrain and ultraviolet/ozone (UVO) treatment of PDMS to control buckling modes (wavy vs. coiled).
• Structural characterization of NW coils and mechanical testing to determine stretchability and strain mitigation.

Main Results:

• Achieved two buckling modes: in-plane wavy and 3D coiled, controlled by UVO treatment.
• Oval-shaped NW coils exhibited remarkable stretchability up to the substrate's failure strain (∼104%).
• Demonstrated single NW devices with stable electrical response over a large strain range.

Conclusions:

• The coil shape effectively mitigates local strain, similar to a spring, enabling large stretchability.
• Si NW coils represent a promising architecture for accommodating various mechanical stresses (tension, compression, bending, twist).
• This fabrication technique and resulting structures hold significant potential for stretchable electronics and related technologies.