Apple's Watch Ultra, with its 2000-nit digital display and GPS capabilities, is a far cry from its Revolutionary War-era self-winding forebears. What sorts of wondrous body-mounted technologies might we see another hundred years hence? In his new book, The Skeptic's Guide to the Future, Dr. Steven Novella (with assists from his brothers, Bob and Jay Novella) examines the history of wearables and the technologies that enable them to extrapolate where further advances in flexible circuitry, wireless connectivity and thermoelectric power generation might lead.
Excerpted from the book The Skeptics' Guide to the Future: What Yesterday's Science and Science Fiction Tell Us About the World of Tomorrow by Dr. Steven Novella, with Bob Novella and Jay Novella. Copyright © 2022 by SGU Productions, Inc. Reprinted with permission of Grand Central Publishing. All rights reserved.
As the name implies, wearable technology is simply technology designed to be worn, so it will advance as technology in general advances. For example, as timekeeping technology progressed, so did the wristwatch, leading to the smartwatches of today. There are certain advances that lend themselves particularly to wearable technology. One such development is miniaturization.
The ability to make technology smaller is a general trend that benefits wearables by extending the number of technologies that are small enough to be conveniently and comfortably worn. We are all familiar by now with the incredible miniaturization in the electronics industry, and especially in computer chip technology. Postage-stamp-sized chips are now more powerful than computers that would have filled entire rooms in prior decades.
As is evidenced by the high-quality cameras on a typical smartphone, optical technology has already significantly miniaturized. There is ongoing research into tinier optics still, using metamaterials to produce telephoto and zoom lenses without the need for bulky glass.
“Nanotechnology” is now a collective buzzword for machines that are built at the microscopic scale (although technically it is much smaller still), and of course, nanotech will have incredible implications for wearables.
We are also at the dawn of flexible electronics, also called “flex circuits” and more collectively “flex tech.” This involves printing circuits onto a flexible plastic substrate, allowing for softer technology that moves as we move. Flexible technology can more easily be incorporated into clothing, even woven into its fabric. The advent of two-dimensional materials, like carbon nanotubes, which can form the basis of electronics and circuits, are also highly flexible. Organic circuits are yet another technology that allows for the circuits to be made of flexible material, rather than just printed on flexible material.
Circuits can also be directly printed onto the skin, as a tattoo, using conductive inks that can act as sensors. One company, Tech Tats, already offers one such tattoo for medical monitoring purposes. The ink is printed in the upper layers of the skin, so they are not permanent. They can monitor things like heart rate and communicate this information wirelessly to a smartphone.
Wearable electronics have to be powered. Small watch batteries already exist, but they have finite energy. Luckily there are a host of technologies being developed that can harvest small amounts of energy from the environment to power wearables (in addition to implantable devices and other small electronics). Perhaps the earliest example of this was the self-winding watch, the first evidence of which comes from 1776. Swiss watchmaker Abraham-Louis Perrelet developed a pocket watch with a pendulum that would wind the watch from the movement of normal walking. Reportedly it took about fifteen minutes of walking to be fully wound.
There are also ways to generate electric power that are not just mechanical power. Four types of ambient energy exist in the environment—mechanical, thermal, radiant (e.g., sunlight), and chemical. Piezoelectric technology, for example, converts applied mechanical strain into electrical current. The mechanical force can come from the impact of your foot hitting the ground, or just from moving your limbs or even breathing. Quartz and bone are piezoelectric materials, but it can also be manufactured as barium titanate and lead zirconate titanate. Electrostatic and electromagnetic devices harvest mechanical energy in the form of vibrations.
There are thermoelectric generators that can produce electricity from differences in temperature. As humans are warm-blooded mammals, a significant amount of electricity can be created from the waste heat we constantly shed. There are also thermoelectric generators that are made from flexible material, combining flex tech with energy harvesting. This technology is mostly in the prototype phase right now. For example, in 2021, engineers published the development of a flexible thermoelectric generator made from an aerogel-silicone composite with embedded liquid metal conductors resulting in a flexible that could be worn on the wrist and could generate enough electricity to power a small device.
Ambient radiant energy in the form of sunlight can be converted to electricity through the photoelectric effect. This is the basis of solar panels, but small and flexible solar panels can be incorporated into wearable devices as well.
All of these energy-harvesting technologies can also double as sensing technology—they can sense heat, light, vibration, or mechanical strain and produce a signal in response. Tiny self-powered sensors can therefore be ubiquitous in our technology.
The technology already exists, or is on the cusp, to have small, flexible, self-powered, and durable electronic devices and sensors, incorporated with wireless technology and advanced miniaturized digital technology. We therefore can convert existing tools and devices into wearable versions, or use them to explore new options for wearable tech. We also can increasingly incorporate digital technology into our clothing, jewelry, and wearable equipment. This means that wearable tech will likely increasingly shift from passive objects to active technology integrated into the rest of our digital lives.
There are some obvious applications here, even though it is difficult to predict what people will find useful versus annoying or simply useless. Smartphones have already become smartwatches, or they can pair together for extended functionality. Google Glass is an early attempt at incorporating computer technology into wearable glasses, and we know how it has been received.
If we extrapolate this technology, one manifestation is that the clothing and gear we already wear can be converted into electronic devices we already use, or they can be enhanced with new functionality that replaces or supports existing devices.
We may, for example, continue to use a smartphone as the hub of our portable electronics. Perhaps that smartphone will be connected not only to wireless earbuds as they are now, but also to a wireless monitor built into glasses, or sensors that monitor health vitals or daily activity. Potentially, the phone could communicate with any device on the planet, so it could automatically contact your doctor’s office regarding any concerning changes, or contact emergency services if appropriate.
Portable cameras could also monitor and record the environment, not just for documenting purposes but also to direct people to desired locations or services, or contact the police if a crime or disaster is in progress.
As our appliances increasingly become part of the “internet of things,” we too will become part of that internet through what we wear, or what’s printed on or implanted beneath our skin. We might, in a very real sense, become part of our home, office, workplace, or car, as one integrated technological whole.
We’ve mostly been considering day-to-day life, but there will also be wearable tech for special occupations and situations. An extreme version of this is exosuits for industrial or military applications. Think Iron Man, although that level of tech is currently fantasy. There is no portable power source that can match Iron Man’s arc reactor, and there doesn’t appear to be any place to store the massive amounts of propellant necessary to fly as he does.
More realistic versions of industrial exosuits are already a reality and will only get better. A better sci-fi analogy might be the loader exo-suit worn by Ripley in Aliens. Powered metal exosuits for construction workers have been in development for decades. The earliest example is the Hardiman, developed by General Electric between 1965 and 1971. That project essentially failed and the Hardiman was never used, but since then development has continued. Applications have mostly been medical, such as helping people with paralysis walk. Industrial uses are still minimal and do not yet include whole-body suits. However, such suits can theoretically greatly enhance the strength of workers, allowing them to carry heavy loads. They could also incorporate tools they would normally use, such as rivet guns and welders.
Military applications for powered exosuits would likely include armor, visual aids such as infrared or night-vision goggles, weapons and targeting systems, and communications. Such exosuits could turn a single soldier into not just enhanced infantry, but also a tank, artillery, communications, medic, and mule for supplies.
Military development might also push technology for built-in emergency medical protocols. A suit could automatically apply pressure to a wound to reduce bleeding. There are already pressure pants that prevent shock by helping to maintain blood pressure. More ambitious tech could automatically inject drugs to counteract chemical warfare, increase blood pressure, reduce pain, or prevent infection. These could be controlled by either onboard AI or remotely by a battlefield medic who is monitoring the soldiers under their watch and taking actions remotely through their suits.
Once this kind of technology matures, it can then trickle down to civilian applications. Someone with life-threatening allergies could carry epinephrine on them to be injected, or they could wear an autoinjector that will dose them as necessary, or be remotely triggered by an emergency medical responder.
Everything discussed so far is an extrapolation from existing technology, and these more mature applications are feasible within fifty years or so. What about the far future? This is likely where nanotechnology comes in. Imagine wearing a nanosuit that fits like a second skin but that is made from programmable and reconfigurable material. It can form any mundane physical object you might need, on command. Essentially, the suit would be every tool ever made.
You could also change your fashion on demand. Go from casual in the morning to business casual for a meeting and then formal for a dinner party without ever changing your clothes. Beyond mere fashion, this could be programmable cosplay—do you want to be a pirate, or a werewolf? More practically, such a nanoskin could be well ventilated when it’s warm and then puff out for good insulation when it’s cold. In fact, it could automatically adjust your skin temperature for maximal comfort.
Such material can be soft and comfortable, but bunch up and become hard when it encounters force, essentially functioning as highly effective armor. If you are injured, it could stem bleeding, maintain pressure, even do chest compressions if necessary. In fact, once such a second skin becomes widely adopted, life without it may quickly become unimaginable and scary.
Wearable technology may become the ultimate in small or portable technology because of the convenience and effectiveness of being able to carry it around with us. As shown, many of the technologies we are discussing might converge on wearable technology, which is a good reminder that when we try to imagine the future, we cannot simply extrapolate one technology but must consider how all technology will interact. We may be making our wearables out of 2D materials, powered by AI and robotic technology, with a brain-machine interface that we use for virtual reality. We may also be creating customized wearables with additive manufacturing, using our home 3D printer.