Laser-engraved capillary networks in cement panels for programmable vertical wetting and evaporative cooling

Background

The broad field is construction and material science oriented towards enhancing fluid transport in porous building components. Water transport and surface wetting are key for evaporative cooling, humidity regulation, self-cleaning facades, and moisture management. Traditional cementitious and clay panels rely on natural capillarity but exhibit slow uptake, poor wetting on vertical surfaces, and limited controllability. Engineers have long sought scalable methods to manage moisture in façades and substrates to reduce energy consumption, mitigate water waste, and enhance environmental resilience.

Conventional techniques for creating fluid pathways—such as hydro-jetting, molding, CNC milling, or casting—produce coarse or uniform channels with low aspect ratios that yield sluggish or unpredictable wetting, especially against gravity. These methods cannot precisely tailor channel depth, width, and network topology, resulting in uneven coverage and limited flow rates. Moreover, mechanical scoring often introduces microcracks and weakens the material, exacerbating durability concerns in freeze–thaw cycles or salt environments. Fabrication constraints on channel geometry and surface morphology further hinder efforts to achieve rapid, programmable fluid distribution across large-area panels.

Technology

Laser engraving on hardened cementitious or clay panels sculpts high-aspect-ratio, V-shaped capillary grooves approximately 4–5 mm deep and 0.5 mm wide by applying high power at low scanning speeds. The localized heat melts and resolidifies groove walls, forming micro-bridges and increasing surface roughness, which reduces the water contact angle from about 22.7° to 16.5° and boosts capillary uptake. By arranging these narrow channels into tailored network patterns, liquid can be driven against gravity, enabling a 100 mm × 100 mm vertical panel to become fully wetted in seven minutes at a 1 mL/min feed rate. Adjustments to channel spacing, depth and inlet number allow precise control of flow capacity and distribution across the surface.

What sets this technology apart is the lasered wall morphology—characterized by buff-colored, resolidified regions and micro-bridges—unachievable by hydro-jetting, molding or milling. These unique features create superior fluid transport performance and programmable wetting direction, even on vertical surfaces, while offering tunable patterns for specific flow requirements. Although micro-cracking and slight strength reductions can occur during engraving, these effects can be mitigated through targeted additives or localized reinforcement, ensuring both durability and enhanced functionality.

Benefits

• Accelerated and programmable capillary fluid transport, enabling vertical flow against gravity
• Enhanced surface wetting via increased roughness and reduced water contact angle
• Superior evaporative cooling performance, achieving up to ~2 °C greater temperature reduction
• Customizable channel network geometry for precise control of flow capacity and distribution
• Unique laser-induced micro-bridges and morphology unattainable by hydro-jetting, molding, or milling
• Scalable fabrication suited for façades, roofs, indoor humidification, self-watering planters, and drainage systems

Applications

• Evaporative cooling facades
• Self-watering planter modules
• Interior wall humidification panels
• Drainage-enhanced pavement surfaces
• Standalone ceramic humidifiers

Additional info

High-power, low-speed laser engraving carves 4–5 mm deep, ~0.5 mm wide V-shaped capillary grooves into cementitious panels. Localized melting/resolidification forms micro-bridges and increases surface roughness, reducing contact angle from ~23° to ~16.5° for boosted capillary uptake. Engineered channel networks drive programmable wetting—even vertically (100×100 mm wetted in 7 min at 1 mL/min). Channel spacing, depth and inlet count tune flow, while laser-induced wall morphology outperforms milling. Trade-offs like micro-cracking are mitigated by additives or reinforcement.