Photocurable Polymer-Based 3D Printing: Advanced Flexible Strain Sensors for Human Kinematics Monitoring

Area of Science:

• Materials Science
• Biomedical Engineering
• Additive Manufacturing

Background:

• Vat photopolymerization-based additive manufacturing (AM) offers solutions for wearable sensors.
• Incorporating nanoparticles into polymer resins enhances mechanical, electrical, and chemical properties for custom nanocomposites.
• Biocompatible materials are crucial for medical applications.

Purpose of the Study:

• To develop accurate, custom strain sensors for wearable applications using additive manufacturing.
• To investigate the use of a biocompatible polymer resin enhanced with multi-walled carbon nanotubes (MWCNTs).
• To assess the performance and characteristics of 3D printed nanocomposite strain sensors.

Main Methods:

• Utilizing a digital light processing (DLP)-based AM system with a low-cost, biocompatible polymer resin.
• Enhancing the resin with multi-walled carbon nanotubes (MWCNTs) and employing planetary shear mixing for uniform dispersion.
• Characterizing sensor performance, including maximum strain, durability, spatial resolution, and MWCNT alignment.

Main Results:

• The 3D printed strain sensors achieved a maximum strain of 244% and maintained performance over hundreds of cycles at lower strain ranges.
• The additive manufacturing process enabled sub-30 micron spatial resolution and facilitated MWCNT alignment in the printing plane.
• High-magnification imagery confirmed uniform MWCNT dispersion and identified MWCNT pullout at fracture points.

Conclusions:

• The developed nanocomposite and 3D printing process are suitable for creating customized, wearable strain sensors.
• These sensors demonstrate significant potential for human kinematics monitoring and sensing, including finger motion detection.
• The biocompatible nature and robust performance make the sensors a strong candidate for medical and wearable technology applications.