Nanopillar

Key takeaways

Nanopillar belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Nanopillar to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Nanopillar from memory before moving on to harder problems.

Reference excerpt

Nanopillars is an emerging technology within the field of nanostructures. Nanopillars are pillar shaped nanostructures approximately 10 nanometers in diameter that can be grouped together in lattice like arrays. They are a type of metamaterial, which means that nanopillars get their attributes from being grouped into artificially designed structures and not their natural properties. Nanopillars set themselves apart from other nanostructures due to their unique shape. Each nanopillar has a pillar shape at the bottom and a tapered pointy end on top. This shape in combination with nanopillars' ability to be grouped together exhibits many useful properties. Nanopillars have many applications including efficient solar panels, high resolution analysis, and antibacterial surfaces.

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 nanowire solar cells. Less material is needed to build a solar cell out of nanopillars compared to regular semi conductive materials. They also hold up well during the manufacturing process of solar panels. This durability allows manufacturers to use cheaper materials and less expensive methods to produce solar panels. Researchers are looking into putting dopants into the bottom of the nanopillars, to increase the amount of time photons will bounce around the pillars and thus the amount of light captured. As well as capturing light more efficiently, using nanopillars in solar panels will allow them to be flexible. The flexibility gives manufacturers more options on how they want their solar panels to be shaped as well as reduces costs in terms of how delicately the panels have to be handled. Although nanopillars are more efficient and cheaper than standard materials, scientists have not been able to mass-produce them yet. This is a significant drawback to using nanopillars as a part of the manufacturing process.

Antibacterial surfaces 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.

Antibacterial mechanism There are several models proposed to explain the antibacterial mechanism of the nanopillars. According to the stretching and mechano-inducing model, 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. Alternative antibacterial mechanism of nanopillars include the potential effects of shear force, negative physiological response of bacteria, and intrinsic pressure effects from the interaction between bacterial surface proteins and nanopillars.

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. This is especially useful in cellular analysis. The cells group around the nanopillars because of its small size and recognize it as an organelle. The nanopillars simply hold the cells in place while the cells are being observed.

Diamond-based quantum sensing Nano pillars are used in quantum technologies to enhance the photon outcoupling efficiency of fluorescent defects. Nanopillars are especially effective in the context of color centers hosted in diamond. Due to the high refractive index of diamond, most of the photons originating from the fluorescence of, e.g. Nitrogen-Vacancy (NV) centers are lost due to total internal reflection. Nanopillars can enhance the outcoupling efficiency and the directionality of the color center emission. This allows significant boosts in sensitivity for the application of NV quantum sensing, both in the context of nanoscale nuclear magnetic resonance and quantum magnetometry (e.g., in the form of scanning probe microscopy). Zhu et al. have shown that it is crucial to include an appropriate tapering of the nanopillars to maximize collection efficiency.

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 reactive ion etching(molding the nanopillars to the right shape) to make large groups of silicon pillars with less than 500 nm diameters. Then, in 2010, researchers fabricated a way to manufacture nanopillars with tapered ends. The former design of a pillar with a flat blunt top reflected much of the light coming onto the pillars. The tapered tops allow light to enter the forest of nanopillars and the wider bottom absorbs almost all of the light that hits it. This design captures about 99% of the light whereas nanorods which have a uniform thickness only captured 85% of the light. After the introduction of tapered ends, researchers started to find many more applications for nanopillars.

Worked examples

Example 1 — a first encounter with Nanopillar

Start with the simplest possible case. Write down what Nanopillar claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Nanopillar before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Nanopillar ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Nanopillar

In research: Nanopillar appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Nanopillar in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Nanopillar is common in secondary-school and first-year university syllabi. It links to neighbouring topics Nanomaterials, so understanding it makes those chapters shorter.
In everyday life: Look for Nanopillar outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Nanopillar in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Nanopillar means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Nanopillar out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Nanopillar in simple terms?

Nanopillars is an emerging technology within the field of nanostructures. Nanopillars are pillar shaped nanostructures approximately 10 nanometers in diameter that can be grouped together in lattice like arrays.

Why does Nanopillar matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Nanopillar?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Nanopillar.