“We took these designs from nature and optimized them,” said Ph.D. candidate Eric Chadwick at the University of Toronto. His lab’s working prototype of a hydrogen fuel cell, based on the finely patterned water-conducting scales of desert lizards and the well-optimized vein patterns of leaves, gained 30% more peak power and better catalyst utilization a breakthrough that might transform how engineers approach one of the most nettlesome problems in electrochemical energy: managing water.
The recurring issue of water accumulation in proton exchange membrane fuel cells (PEMFCs) has been a confounding factor in attempts to commercialize hydrogen technology for years. As hydrogen and oxygen react on opposite sides of the membrane, water is a byproduct of the reaction. Insufficient, and the membrane dehydrates, lowering conductivity and cell lifespan. Excessive water inundates the catalyst layer, impedes gas flow, and asphyxiates performance. Conventional flow field architectures serpentine, parallel, interdigitated each provide pressure drop-water removal-reactant distribution trade-offs but none have solved the challenge of stable, high-power operation at high humidity or non-steady loads.
Their solution was discovered by Chadwick’s group not in the lab, but in nature. Some desert lizards, like the thorny devil of Australia, use a system of connected capillary channels between their scales to actively channel limited water towards their mouths based on capillary action, not force. Likewise, leaf vein structures effectively route water from the surface to the roots through branching and best angle evolved for efficiency. By laser-engraving microchannels onto graphite flow field plates, the scientists replicated these capillary structures, allowing water to be wicked away from the catalyst layer with efficiencies that are nothing short of incredible.
The engineering basis for this method is rooted in the physics of capillarity. In the lizard-inspired microchannels, the capillary pressure (as quantified by the Young–Laplace equation) prevails over gravitational and viscous forces, even when the channel size is engineered up for practical purposes. As described in a new paper in Energy & Environmental Science, the designed graphite plates had capillaries 50 μm wide and 300 μm deep, which were optimized for the quick removal of water. The water contact angle on these hydrophilic surfaces was 36°, facilitating quick wicking at rates of up to 2.3 mm/s matching that of the natural systems it mimics.
When implemented within a PEMFC with a lung-inspired fractal flow field another homage to the optimized distribution networks found in nature the integrated system provided flood-free, stable performance at 100% relative humidity. This is a huge improvement over traditional serpentine designs, which normally flood and experience voltage degradation under such conditions. The prototype reached a maximum current density of 2 A/cm² and a power density of 700 mW/cm², surpassing not only traditional but also other high-end water management approaches, such as porous water transport plates and gas diffusion layers modified.
Its advantages go beyond pure numbers. Electrothermal mapping and neutron imaging investigations have demonstrated that lizard-inspired flow fields provide more homogeneous current and temperature distributions over the cell, minimizing localized hotspots and alleviating catalyst degradation. At elevated current densities, the enhanced water management preserves membrane hydration and reduces ohmic losses as water production and heat generation rise. The capillary-powered system decreases reliance on high-pressure gas streams to remove water, reducing parasitic energy losses and allowing for simpler, more scalable fuel cell designs.
This blending of engineering and biology is representative of a larger shift in clean technology. Biomimicry, as defined by Janine Benyus and examined in recent systematic reviews, is moving from superficial copying to a profound, systems-level incorporation of nature’s design principles. The NICE (Nature-Inspired Chemical Engineering) approach, for instance, focuses not simply on mimicking forms but comprehending the underlying processes like scalability, robustness, and energy minimization that ensure that natural systems are efficient and resilient. As Panagiotis Trogadas and others explained in their 2024 paper, Rather than imitating nature out of context, as in narrow biomimicry, the NICE approach is based on fundamental understanding of key principles underpinning desirable, superior features in biological and other natural systems, such as scalability, robustness, and efficiency.
The practical implications are significant. Better water management in PEMFCs makes possible efficient, maintenance-free hydrogen power for off-grid homes, refrigerated trucks, and emergency shelters uses where diesel generators are now the norm. Municipalities and businesses could use these systems to minimize air pollution and greenhouse gas emissions, not to mention lower operating costs and easier maintenance. Its low-pressure drop and scalable design also make larger freight transport and stationary power fuel cell stacks possible, where standard designs run into cost and durability issues.
The innovation does not end at the cell level. As discussed in recent urban biomimicry research, the same general principles that direct lizard scales and leaf veins are being used to design water-harvesting facades, adaptive urban drainage systems, and even city infrastructure. Combining biomimetic strategies across scales from microfluidic channels to urban water cycles provides a route to regenerative, resilient cities that harvest energy and resources as effectively as the ecosystems they draw inspiration from.
Chadwick’s group is already developing plans to scale up their tech with sophisticated computer modeling to optimize channel geometries and manufacturing processes for mass production. The application of printed circuit board materials and femtosecond laser micromachining may further decrease cost and weight, placing nature-inspired flow fields within reach for a broad variety of fuel cell applications.
As the technology evolves, the task will be to reconcile competing requirements uniform reactant distribution, low pressure drop, strong water removal, and manufacturability using multi-criteria optimization. The development history of fuel cell engineering is full of incremental steps, but the step made possible by biomimetic design marks a new era in which nature’s tried-and-true solutions are comprehensively converted into technological innovation. In Chadwick’s words, “there’s always room for more improvement.”
