Nanotechnology might not be on the front of most peoples’ minds on a given day, but almost all of us not only come in contact with it on a daily basis, but have come to rely on it for our everyday activities. The most obvious and ubiquitous example is in our cell phones, tablets and computers, as well as a host of other electronic smart devices. The current iPhone 12 for example has the Apple A14 Bionic chip with approximately 11.8 billion transistors, each with a minimum feature size of only 5 nanometers (nm)! Ok, so how big is a nanometer? The image below attempts to give you a sense of scale, but maybe the most relatable example is in the diameter of a human hair, which is approximately 100 millionth of a meter wide. A nanometer is a billionth of a meter (10^-9 m), so that means you could fit 100,000 nanometers in the diameter of one of your hairs.
It’s a bit difficult to imagine, but using what is called Nanofabrication, we can design these devices in a computer program, decide what materials and dimensions we would like, and then proceed to fabricate them with nanometer resolution on mass scale. It is certainly without a doubt one of humanities most impressive technological accomplishments. In fact, the push by companies like Intel, IBM, AMD, and others to cram more and more transistors on a single chip is what lead to advances in nanotechnology and more specifically nanofabrication (see Moore’s Law for more details). More transistors mean more computational power and more memory for your device and as consumers, we have always had an unquenched thirst for faster, smaller, and smarter computers.
Nanotechnology is an ever-growing field, finding applications in almost every technological and product sector. It is also incredibly diverse in how structures and devices are made. Let us now make a distinction between two main methodologies in nanotechnology, bottom-up and top-down, however as the fields advance, the lines between the two are now blurring as integrative efforts are employed to overcome new scientific and technological challenges.
Bottom-up nanotechnology or nanoscience is typically carried out by chemists, biologists, and other scientists and engineers who specialize in forming nanostructures through chemical or biological reactions. These nanostructures are most often formed in solution phase and allow for large batch processing at scale. A few examples of bottom-up nanotechnology in everyday life are:
Cosmetics and other body products. Different types of nanomaterials are employed in cosmetics including nanosomes, liposomes, fullerenes, solid lipid nanoparticles and more. For example, nanoparticles of zinc oxide and titanium dioxide are often used to help absorb or reflect harmful ultraviolet light in sunscreens.
Clothing and furniture. Silica nanoparticles are now used to help create waterproof or stain-proof clothing. Carbon nanofibers can be incorporated into furniture fabric to have the same effect, while also making furniture less flammable.
Medical treatments and diagnosis. Nanoparticles are now being used as drug delivery systems, gene therapy agents, enabling new rapid diagnostics, and much more. Bottom-up nanotechnology maybe holds its most promising and diverse applications in this space.
Top-down nanotechnology is where traditional nanofabrication lives. Again, most of these techniques were born from the push to shrink integrated circuits for computing; however, modern scientists and engineers now utilized these techniques across a broad area of application spaces. Not only does your current cell phone have a chip with nanofabricated processers, but also its memory and video chips, accelerometers used to sense motion, miniature microscale microphones used for talking and noise cancellation, tiny lasers and light sensors for facial recognition, tiny ultra-high resolution image detectors in your camera, pressure sensitive sensors for touch, organic light emitting diodes in your brilliant screens and much more! Beyond commercial devices nanofabricated devices are now finding their way into every inch of our life. A few examples are:
Accelerometers and gyroscopes. These are micro and nanoscale devices that sense motion and forces, the same found in your phones, but also found in laptops to detect falls, cars to deploy airbags, planes to help with stabilization, your fitness trackers to sense your movement and several other places, including many new applications in the health care industry.
Lab-on-a-chip devices. Nanofabrication allows us to shrink an entire laboratory onto a tiny chip, with small micro and nanoscale channels to mix chemicals and evaluate reactions electrically or visually. One of the most powerful and recent is the Nanopore device allowing for the sequencing any DNA/RNA fragment in a portal device.
Nanophotonic devices. Nanofabrication allows us to make structures on the same scale as visible light, giving us the ability to manipulate light in unique ways. For example, more efficiently extracting light from LED materials, trapping light in thin films for better solar cells or sensing devices, and focusing light to make ultra-thin and light optical lenses.
For modern day devices, nanofabrication is a complex series of steps carried out sequentially by sophisticated equipment in cleanroom facilities. To give you a better sense of how this is accomplished, this post will be followed by additional blog posts, each focusing on one of the main steps involved the process, of which include photolithography, etching, deposition, and metrology. Nanofabrication techniques are key to unlocking a whole new generation of devices that have the power to help improve the lives of ourselves and others. Come learn more about it with us!
About the Author: Jacob Trevino, PhD. (https://www.jacobtrevino.com/)