Cephalopods (e.g., squids, octopuses, and cuttlefish) have captivated the imagination of both the general public and scientists alike due to their sophisticated nervous systems, complex behavioral patterns, and visually stunning camouflage displays. Given their unique capabilities and characteristics, it is not surprising that these marine invertebrates have emerged as exciting models for novel adaptive optical and photonic materials. Within this context, our laboratory has developed various cephalopod-derived and cephalopod-inspired systems with dynamic functionalities within the visible and infrared regions of the electromagnetic spectrum. Our findings hold implications for next-generation biomedical imaging technologies and adaptive camouflage devices.

Morpho butterfly’s blue is well known, but, mysterious. The color is produced by interference from an ORDERED nanostructure, whereas the single color in wide angles contradicts the interference. This mystery is attributed to a specific nanostructure having both ORDER and DISORDER. Converting this reflective principle to transmission, we have proposed a new daylight window with high transmittance, wide angular spread, and low color dispersion, which have been impossible to meet simultaneously because of their trade-off relationship. Although our originally proposed nanostructure was difficult to fabricate, we have designed a new structure to solve the problem. Finally, an effective nanostructure was verified using numerical simulations.

Nucleate pool boiling is enhanced by facilitating water transport to the boiling surface. Doing so in an industrial boiler could improve the energy efficiency of the Rankine cycle widely used in power plants. The fundamental problem of water transport is solved in myriad ways in biology, particularly in the vascular structure, or xylem, of plants. The structure varies, from straw like tracheids in ferns and conifers, to sponge like reticulate vessels in many angiosperms. The latter morphology is of particular interest, as fabrication processes exist for reticulate metal foams and sintered metal wicks that mimic the porous xylem of angiosperms. Couple this bioinspired bulk morphology with an anodization surface treatment, and a functional, composite material is obtained. The anodization step imparts surface micro-porosity on the already bulk-porous metal foam, further increasing surface area to heat transfer. Varying degrees of surface modification may be achieved by varying anodization voltage, treatment time, and electrolyte concentration. The combined effect is expected to increase the active nucleation site density by about one order of magnitude. In this study, a method is proposed that involves back tracking bubbles to the moment of their departure from the boiling surface. This approach enables quantification of bubbles in nucleate pool boiling even at moderate heat fluxes. An apparatus has been fabricated to measure boiling enhancement and facilitate visualization. It is expected that this study will contribute to greater theoretical and material understanding of boiling on porous anodized boiling surfaces.

We describe here a new class of smart composites that respond to environmental humidity and temperature. These composites are made of shape memory epoxy and flax fibres, and change their shape because of the hygroscopic strain effects between fibres, matrix and their bilayer composite architecture. The smart biobased composites we propose here can also be programmed at different humidity and shape states via the SMP effect of the epoxy. We demonstrate the high stiffness of these smart composites but also their programmable and re-programmable characteristics, together with the large curvatures and actuation authority they can achieve.

Development of self-healing materials is an influential step towards greener technologies and a sustainable future. We propose a novel approach of post-modification of polymers by a gas-phase infiltration technique, which enriched the variety of existing self-healing inorganic materials with the class of metal oxides. The successfully tested zinc and indium oxides are the constituting materials of the most widely used transparent conductive oxides, such as indium tin oxide (ITO) or indium-doped zinc oxide (IZO). Therefore, this invention might benefit numerous technological areas: flexible electronics, wearable sensors, photovoltaics, displays, energy by potentially enhancing the durability and longevity of the materials.

Conventional optical sensing devices require bulky and sophisticated optical systems to obtain high-quality information. Over the last decades, photonic metamaterials have attracted considerable interest in various sensing applications due to their compactness and high performance capabilities. However, millions of years of evolution in the biological world has developed a plethora of unique micro- and nanoscopic photonic structures to perform versatile vision and sensory functions. In this talk, I will discuss how the development of nanophotonic devices harnessing bioinspired attributes can provide novel yet highly practical solutions for ophthalmic sensing applications. Inspired by the multifunctional nanostructures on the wings of glasswing butterflies, we first develop Si3N4-based nanostructures onto a Fabry-Perot-resonator-based intraocular pressure (IOP) sensor for glaucoma management. The metasurface integration onto the IOP sensor led to a 2.5-fold improvement in readout angle allowing easy handheld monitoring and in a one-month in vivo study conducted in rabbits, showed a 3-fold reduction in IOP error and 12-fold reduction in tissue encapsulation and inflammation, compared to an IOP sensor without nanostructures. I will further show its application in optical wearables and contact lenses where, we developed a nanostructured scleral lens with enhanced optical, bactericidal, and sensing capabilities. The bioinspired nanostructures, made on biocompatible parylene thin-films are mounted on the anterior and posterior side of a traditional scleral lens. Compared to a traditional scleral lens, the nanostructured scleral lens minimizes glare at large viewing angles of 80o by 4.3-fold, and block UVA light while offering greater transmission in the visible regime. Furthermore, they display potent bactericidal activity against Escherichia coli, killing 89% of tested bacteria within 4 hr in vitro. The same nanostructures conformally coated with gold are used to perform simple, rapid, and label-free multiplex detection of lysozyme and lactoferrin (protein biomarkers of chronic dry eye disease) in artificial and whole human tears using drop coating deposition Raman spectroscopy within their physiological and pathological concentration range.

In a bioinspired approach, we are mimicking various types of naturally occurring materials to fabricate hybrid antibacterial and biocompatible thin films for a range of applications. Natural chitin and chitinoid materials have outstanding physical and biological properties, among those being antimicrobial properties, which inspired us to develop a process for growing biomimetic organic chitinoid and hybrid organic-inorganic metallochitin thin films by applying Molecular Layer Deposition (MLD). This work highlights a novel method to prepare conformal ultrathin films of chitin and hybrid chitin-based biomaterials from the gas phase by Molecular Layer Deposition (MLD) technique. MLD is a thin film growth technique, where the structure is built through sequential self-terminating gas–solid reactions. This project has received funding from the European Union´s Horizon 2020 research and innovation programme under the Marie Sklodowska -Curie grant agreement No 765378.

Inspired by the unique characteristics of the natural creatures, many ice-phobic materials have been developed that can remove ice from the surface by means of external forces such as wind, gravity, and vibration. Here, the biphilic surface endowed with the superh-hydrophobic/super-hydrophilic property is discussed for its application of preventing the accumulation of snow, frost, or ice, on which the special wettability is helpful for ice-melting or de-icing.

Many physico-chemical properties shown by natural materials usually have their origin in a multi-scale, hierarchical structure based on a rather small selection of primary constituents. In fact, materials with wholly different properties are found in biological species just by spatially arranging their constituents at different length scales and in different ways. Within this context, the surface of stainless steel and titanium alloys was textured at the micro- and nano-scales aiming at using a hierarchical biomimetic approach to control cell attachment, proliferation, and migration. This approach has been followed based on the tremendous influence of the surface properties of biomaterials on the specific biological response of the surrounding tissues. In this regard, the precise control of the interaction between cells and the surface of materials allows tailoring and optimizing the performance of implants and prostheses integrated into the body. Different micro- and nano-structured surfaces were fabricated by femtosecond (fs) laser processing taking advantage of the fact that fs Laser Induced Periodical Surface Structures (LIPSS) nanopatterns are generated perpendicular to the laser beam polarization and therefore their orientation can be controlled. Various micro-/nano-pattern distributions and combinations were evaluated aiming at determining their influence in the cell culture viability, cell migration through the lines, and cell morphology.