Microengineered photonic topsheet for heme retention and broadband stain masking

Overview

This technology presents a skin-safe, bio-based multilayer architecture designed for absorbent hygiene products. It combines a 3D optical scattering surface with a subsurface fluid-transport and cell-sieving layer to conceal colored components, such as blood stains, below an optical interface while keeping the surface clean.

The top layer incorporates cellulose nanocrystal (CNC) structures with chiral nematic and Mie-scattering micro-textures, providing high optical opacity and diffuse red-light scattering to mask underlying stains. Beneath this, a micro-channel gradient rapidly draws fluid along the Z-axis while pore gradients physically capture red blood cells (~6–8 µm) and hemoglobin at the core boundary. The design serves as a topsheet or acquisition distribution layer (ADL) replacement.

Key benefits:

• Skin-safe, naturally hydrophilic cellulose materials eliminate chemical safety concerns
• Preserves dryness, leak protection, and fluid handling performance
• Maintains acquisition, retention, and comfort under compression
• Compatible with high-speed roll-to-roll converting processes

Technical specifications

The architecture is fabricated using silicon/PDMS micro- and nano-patterning to create masters for replication:

• Optical scattering surface: CNC chiral nematic structures and Mie-scattering micro-textures deliver high opacity and diffuse red-light scattering to mask stains
• Fluid transport layer: micro-channel gradients draw fluid rapidly along the Z-axis
• Cell-sieving layer: pore gradients physically capture red blood cells (~6–8 µm) and hemoglobin at the core boundary
• Surface engineering: contact angle tuning ensures rapid fluid acquisition while maintaining surface cleanliness
• Scalability: pattern transfer supports high-speed roll-to-roll converting with minimal disruption

Technology readiness level

The technology is in the research and validation stage. A three-phase validation plan is in place:

• Phase 1: optical design and master fabrication using computational optics to optimize Mie-scattering micro-textures and chiral nematic CNC structures
• Phase 2: microfluidic performance optimization, including Z-axis pore gradients and surface energy tuning
• Phase 3: empirical validation using spectrophotometry to quantify diffuse reflectance and stain-masking efficacy with whole blood and realistic simulants under mechanical compression and prolonged wear, followed by establishing roll-to-roll processing parameters

The research team brings expertise in optical design, contact angle engineering, and spectrophotometry to support rapid prototyping and quantitative validation.