Nanopillar

Nanopillars is an emerging technology within the field of

Applications

Solar panels

Due to their tapered ends, nanopillars are very efficient at capturing light. Solar collector surfaces coated with nanopillars are three times as efficient as

Nanopillars also have functions outside of electronics and can imitate nature's defenses. Cicadas' wings are covered in tiny, nanopillar shaped rods. When bacteria rests on a cicada's wing, its cell membrane will stick to the nanopillars and the crevices between them, rupturing it. Since the rods on the cicadas are about the same size and shape as artificial nanopillars, it is possible for humans to copy this defense. A surface covered with nanopillars would immediately kill off all soft membrane bacteria. More rigid bacteria will be more likely to not rupture. If mass-produced and installed everywhere, nanopillars could reduce much of the risk of transmitting diseases through touching infected surfaces. ^[5]

Antibacterial mechanism

There are several models proposed to explain the antibacterial mechanism of the nanopillars. According to the stretching and mechano-inducing model,^[6] for a relatively uniform nanotopographies like nanopillars found on cicada wing, the bacteria die due to the rupturing of bacterial cell wall that is suspended between two adjacent nanopillars as opposed to a puncturing mechanism. The nanopillar features like height, density, and sharpness of the nanopillars was found to be affecting the overall antibacterial properties of the nanopillars. However, the relative correlation of nanopillar features is difficult to establish due to several conflicting results in the literature.^[7] Alternative antibacterial mechanism of nanopillars include the potential effects of shear force,^[8] negative physiological response of bacteria,^[9] and intrinsic pressure effects from the interaction between bacterial surface proteins and nanopillars.^[10]

High resolution molecular analysis

Another use of nanopillars is observing cells. Nanopillars capture light so well that when lights hits them, the glow the nanopillars emit dies down at around 150 nanometers. Because this distance is less than the wavelength of light, it allows researchers to observe small objects without the interference of background light.^[11] This is especially useful in cellular analysis. The cells group around the nanopillars because of its small size and recognize it as an organelle.^[12] The nanopillars simply hold the cells in place while the cells are being observed.

History

In 2006, researchers at the University of Nebraska-Lincoln and the Lawrence Livermore National Laboratory developed a cheaper and more efficient way to create nanopillars. They used a combination of nanosphere lithography (a way of organizing the lattice) and

See also

Manufacturing process

Constructing nanopillars is a simple but lengthy procedure that can take hours.^[15] The process to create nanopillars starts with anodizing a 2.5 mm thick aluminum foil mold. Anodizing the foil creates pores in the foil a micrometer deep and 60 nanometers wide. The next step is to treat the foil with phosphoric acid which expands the pores to 130 nanometers. The foil is anodized once more making its pores a micrometer deeper. Lastly, a small amount of gold is added to the pores to catalyze the reaction for the growth of the semiconductor material. When the aluminum is scraped away there is a forest of nanopillars left inside a casing of aluminum oxide.^[16] Furthermore, pillar and tube structures can also be fabricated by the top-down approach of the combination of deep UV (DUV) lithography and atomic layer deposition (ALD).^[17][18]

References