The Impact of Invisible Nanotechnology

Nanotechnology will shape society, but scientists and the public have a say in just how much.

4 min read
The Impact of Invisible Nanotechnology
Image: Nicolle Rager Fuller/National Science Foundation

Robots that fight fires, cars that drive themselves, clothes that prevent illness—are they the stuff of science fiction? Or are they more likely than we think? “Life in 2030,” a one-hour special from the radio series Engineers of the New Millennium, explores the latest discoveries to give listeners an idea of how technology will shape our lives in the not-too-distant future.

The Impact of Invisible Nanotechnology


TRANSCRIPT:

Susan Hassler: Whatever the future holds for us in 2030, I think it’s safe to say that nanotechnology will play a huge role.

Dave Guston: As it evolves, it is going to be anywhere and everywhere, the same way that computer chips are not just in computers but they’re in toys, they’re in automobiles, they’re in pens

Phil Ross: Dave Guston is not an engineer working on some new nanomaterial. He’s actually a political scientist, head of the Center for Nanotechnology in Society at Arizona State.

Susan Hassler: We wanted to know how nanotechnology is going to change society over the next 20 years, but as Glenn Zorpette found out, it may be society that changes nanotechnology

Glenn Zorpette: Right—because nanotechnology will be shaped by society—just how much is partly up to its citizens.

Dave Guston: If they want to have a say in what their socio-technical environment looks like in 2030, they’ve still got the opportunity to do that. They don’t have to wait until the nanotechnology product is on the shelf, until the nanotechnology system is entirely embedded in the world that they live.

Glenn Zorpette: So, here’s how it works: Nanotechnology researchers study and manipulate matter smaller than the size of individual atoms and molecules. Nanometers are so small that one sheet of paper is 100 thousand nanometers thick. And at that scale, matter behaves differently, opening the door to amazing nanomaterials and nanosystems—from futuristic sounding concepts like a cloaking device that can render objects invisible to innovations that could very well be on the market before 2030, like more effective cancer therapies, more efficient batteries, and cheaper solar cells

Mark Wiesner: I mean the benefits are tremendous, right? They’re going to give us better, cleaner sources of energy. They’re going to improve nanomedicine. They’re going to really revolutionize the way we live.

Glenn Zorpette: Because the behavior of nanomaterials and systems is new territory, it’s been important to study their potential risks and secondary implications along with their special capabilities

Like Dave Guston, environmental engineer Mark Wiesner runs a center working on future scenarios—Duke University’s Center for the Environmental Implications of Nanotechnology, or CEINT for short

Mark Wiesner: This is the CEINT mesocosm facility. And it simulates a freshwater wetland. So, you have some of these plants, which were selected….

Glenn Zorpette: Wiesner and his team are studying how nanomaterials—in this experiment, silver nanomaterials—interact with plants, microbes, and fish in an ecosystem

Mark Wiesner: We do all these experiments in a lab and the nanomaterials that really will be seen in the environment, the nanomaterials that people and organisms will see, are going to be very different from the ones that come out of the lab. They change. Nature changes them.

Helen Hsu-Kim: We’re now realizing that really looking at transformations of these nanomaterials in the environment is one of the key things that we have to be able to understand to be able to say something about their potential risks.

Glenn Zorpette: Geochemist Helen Hsu-Kim and the other researchers are designing better ways to evaluate nanomaterials. Their goal is to map potential risks and develop a framework for decisions that society will have to make in the future.

Helen Hsu-Kim: That’s what’s exciting about this new approach we’re taking in terms of being proactive about trying to look at unintended consequences of a new industry, a new technology.

Mark Wiesner: What we’re doing are developing methods that allow us to take the most recent information we have, incorporate it mathematically into these descriptions of risk and give us an understanding of not only what our best guess of the risk might be but really, perhaps more importantly, what’s the uncertainty of the risk.

Glenn Zorpette: Back in Arizona, at the Center for Nanotechnology in Society, one of their projects places social scientists in the lab with researchers. Here’s Dave Guston again.

Dave Guston: And it starts off very simply where the social scientist will ask, “What are you doing? Why are you doing that? Could you do it any differently? What do you hope to get out of it?” And those very simple questions create this Socratic dialogue through which the scientists and engineers begin to reconceptualize some of what they’re doing in their research and understand that their research and the decisions that they make in the laboratory have different kinds of consequences for people who are outside of the laboratory, for the rest of us in society.

Glenn Zorpette: Cynthia Selin runs the center’s Anticipation and Deliberation program.

Cynthia Selin: Much of what I’m doing when I’m creating spaces for reflection about futures with scientists, with policymakers, with businesspeople is really to try to make explicit their expectations of the future, to lay out on the table what kind of changes they think are on the horizon and what they’re working towards, and it’s really that making more real and tangible the future that’s of great value and that I hope will maximize the positive benefits of nanotechnology and minimize the negative ones.

Glenn Zorpette: Because no one can say for certain what the future holds, these scientists and engineers prefer to…anticipate

Dave Guston: Which is looking toward the future, not looking at the future as a thing, as if one thing is going to happen in the future that we can predict, but looking toward a variety of plausible futures that we can begin to act around and toward in things that we do today.

Glenn Zorpette: I’m Glenn Zorpette.

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The Inner Beauty of Basic Electronics

Open Circuits showcases the surprising complexity of passive components

5 min read
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A photo of a high-stability film resistor with the letters "MIS" in yellow.
All photos by Eric Schlaepfer & Windell H. Oskay
Blue

Eric Schlaepfer was trying to fix a broken piece of test equipment when he came across the cause of the problem—a troubled tantalum capacitor. The component had somehow shorted out, and he wanted to know why. So he polished it down for a look inside. He never found the source of the short, but he and his collaborator, Windell H. Oskay, discovered something even better: a breathtaking hidden world inside electronics. What followed were hours and hours of polishing, cleaning, and photography that resulted in Open Circuits: The Inner Beauty of Electronic Components (No Starch Press, 2022), an excerpt of which follows. As the authors write, everything about these components is deliberately designed to meet specific technical needs, but that design leads to “accidental beauty: the emergent aesthetics of things you were never expected to see.”

From a book that spans the wide world of electronics, what we at IEEE Spectrum found surprisingly compelling were the insides of things we don’t spend much time thinking about, passive components. Transistors, LEDs, and other semiconductors may be where the action is, but the simple physics of resistors, capacitors, and inductors have their own sort of splendor.

High-Stability Film Resistor

A photo of a high-stability film resistor with the letters "MIS" in yellow.

All photos by Eric Schlaepfer & Windell H. Oskay

This high-stability film resistor, about 4 millimeters in diameter, is made in much the same way as its inexpensive carbon-film cousin, but with exacting precision. A ceramic rod is coated with a fine layer of resistive film (thin metal, metal oxide, or carbon) and then a perfectly uniform helical groove is machined into the film.

Instead of coating the resistor with an epoxy, it’s hermetically sealed in a lustrous little glass envelope. This makes the resistor more robust, ideal for specialized cases such as precision reference instrumentation, where long-term stability of the resistor is critical. The glass envelope provides better isolation against moisture and other environmental changes than standard coatings like epoxy.

15-Turn Trimmer Potentiometer

A photo of a blue chip
A photo of a blue chip on a circuit board.

It takes 15 rotations of an adjustment screw to move a 15-turn trimmer potentiometer from one end of its resistive range to the other. Circuits that need to be adjusted with fine resolution control use this type of trimmer pot instead of the single-turn variety.

The resistive element in this trimmer is a strip of cermet—a composite of ceramic and metal—silk-screened on a white ceramic substrate. Screen-printed metal links each end of the strip to the connecting wires. It’s a flattened, linear version of the horseshoe-shaped resistive element in single-turn trimmers.

Turning the adjustment screw moves a plastic slider along a track. The wiper is a spring finger, a spring-loaded metal contact, attached to the slider. It makes contact between a metal strip and the selected point on the strip of resistive film.

Ceramic Disc Capacitor

A cutaway of a Ceramic Disc Capacitor
A photo of a Ceramic Disc Capacitor

Capacitors are fundamental electronic components that store energy in the form of static electricity. They’re used in countless ways, including for bulk energy storage, to smooth out electronic signals, and as computer memory cells. The simplest capacitor consists of two parallel metal plates with a gap between them, but capacitors can take many forms so long as there are two conductive surfaces, called electrodes, separated by an insulator.

A ceramic disc capacitor is a low-cost capacitor that is frequently found in appliances and toys. Its insulator is a ceramic disc, and its two parallel plates are extremely thin metal coatings that are evaporated or sputtered onto the disc’s outer surfaces. Connecting wires are attached using solder, and the whole assembly is dipped into a porous coating material that dries hard and protects the capacitor from damage.

Film Capacitor

An image of a cut away of a capacitor
A photo of a green capacitor.

Film capacitors are frequently found in high-quality audio equipment, such as headphone amplifiers, record players, graphic equalizers, and radio tuners. Their key feature is that the dielectric material is a plastic film, such as polyester or polypropylene.

The metal electrodes of this film capacitor are vacuum-deposited on the surfaces of long strips of plastic film. After the leads are attached, the films are rolled up and dipped into an epoxy that binds the assembly together. Then the completed assembly is dipped in a tough outer coating and marked with its value.

Other types of film capacitors are made by stacking flat layers of metallized plastic film, rather than rolling up layers of film.

Dipped Tantalum Capacitor

A photo of a cutaway of a Dipped Tantalum Capacitor

At the core of this capacitor is a porous pellet of tantalum metal. The pellet is made from tantalum powder and sintered, or compressed at a high temperature, into a dense, spongelike solid.

Just like a kitchen sponge, the resulting pellet has a high surface area per unit volume. The pellet is then anodized, creating an insulating oxide layer with an equally high surface area. This process packs a lot of capacitance into a compact device, using spongelike geometry rather than the stacked or rolled layers that most other capacitors use.

The device’s positive terminal, or anode, is connected directly to the tantalum metal. The negative terminal, or cathode, is formed by a thin layer of conductive manganese dioxide coating the pellet.

Axial Inductor

An image of a cutaway of a Axial Inductor
A photo of a collection of cut wires

Inductors are fundamental electronic components that store energy in the form of a magnetic field. They’re used, for example, in some types of power supplies to convert between voltages by alternately storing and releasing energy. This energy-efficient design helps maximize the battery life of cellphones and other portable electronics.

Inductors typically consist of a coil of insulated wire wrapped around a core of magnetic material like iron or ferrite, a ceramic filled with iron oxide. Current flowing around the core produces a magnetic field that acts as a sort of flywheel for current, smoothing out changes in the current as it flows through the inductor.

This axial inductor has a number of turns of varnished copper wire wrapped around a ferrite form and soldered to copper leads on its two ends. It has several layers of protection: a clear varnish over the windings, a light-green coating around the solder joints, and a striking green outer coating to protect the whole component and provide a surface for the colorful stripes that indicate its inductance value.

Power Supply Transformer

A photo of a collection of cut wires
A photo of a yellow element on a circuit board.

This transformer has multiple sets of windings and is used in a power supply to create multiple output AC voltages from a single AC input such as a wall outlet.

The small wires nearer the center are “high impedance” turns of magnet wire. These windings carry a higher voltage but a lower current. They’re protected by several layers of tape, a copper-foil electrostatic shield, and more tape.

The outer “low impedance” windings are made with thicker insulated wire and fewer turns. They handle a lower voltage but a higher current.

All of the windings are wrapped around a black plastic bobbin. Two pieces of ferrite ceramic are bonded together to form the magnetic core at the heart of the transformer.

This article appears in the February 2023 print issue.

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