Femtosecond-laser-textured molds for durable, skin-like silicone test surfaces

Overview

This research program develops durable, skin-like silicone test surfaces for evaluating how fluids spread, smear, transfer, and interact with textured materials. The approach uses femtosecond laser processing to machine metal molds with skin-inspired surface patterns, then casts silicone samples from those molds. Because features can be made as small as 2 µm, the molds can combine larger skin-like grooves and raised areas with finer pits and pillars, enabling systematic study of how texture affects liquid retention, release, wetting, and friction.

The resulting silicone surfaces are intended to reproduce key surface behaviors of human skin without relying on coatings or surface treatments whose wetting effects may fade over time. Target applications include consumer product testing, skin-contact materials, cosmetics, and healthcare products where realistic skin analogs are needed for evaluating fluid handling, smearing, and feel.

Technical specifications

Key technical elements:

• Femtosecond laser micromachining of metal molds with feature sizes down to 2 µm; several test designs can be combined on a single mold for direct comparison.
• Silicone casting from textured molds, with smooth silicone samples as controls.
• Skin-inspired surface design based on published skin topography, including grooves, raised areas, pits, and pillars with varying spacing and area coverage.
• Surface characterization using optical profilometry/confocal microscopy and atomic force microscopy (AFM) for roughness parameters including Sq, Sdr, and Vvc.
• Wetting measurements using advancing/receding contact angles and roll-off angles.
• Fluid spreading, smearing, and transfer assessed through top-down imaging of initial and residual fluid coverage.
• Friction measurements performed with an in-house sled tester, targeting a coefficient of 0.4–0.6 and cross-checked against an established reference method.
• If texture alone is insufficient, covalent grafting via plasma activation and silane/PEG chemistry can be added to tailor surface chemistry.
• Durability testing includes repeated rubbing, tens of wash cycles, and storage.

Molds are reusable, allowing consistent production of multiple sample batches for wear, cleaning, and comparative studies.

Technology readiness level

This is an early-stage research effort. The femtosecond laser processing capability and related characterization tools are available, but the specific mold designs and silicone surface samples described here have not yet been produced or validated. A nine-month validation plan is proposed to design, fabricate, and test the surfaces, select the best-performing patterns, and produce sample sets with associated characterization data. After successful validation, the reusable molds and sample sets would be ready for broader evaluation and adoption in product development.