Here comes the thermoelectric future: We tried out the next generation of self-powered sensors

Matrix Industries wants to find ways to keep the connected world of tomorrow running forever, via heat, solar and maybe other sources.

Scott Stein Editor at Large
I started with CNET reviewing laptops in 2009. Now I explore wearable tech, VR/AR, tablets, gaming and future/emerging trends in our changing world. Other obsessions include magic, immersive theater, puzzles, board games, cooking, improv and the New York Jets. My background includes an MFA in theater which I apply to thinking about immersive experiences of the future.
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  • Nearly 20 years writing about tech, and over a decade reviewing wearable tech, VR, and AR products and apps
Scott Stein
6 min read
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I'm in a parking lot in Menlo Park, California, eyeballing a small canister that looks like an Amazon Echo with a fringe on top. It's a location beacon, but it's not plugged into a power source. In fact, it's not powered by anything other than ambient temperature. Despite that fact, it's showing up on the phone screen, actively pinging external devices.

This is a simulation of what a self-powered beacon would be like when dropped into the real world -- imagine it living on a remote trailhead, in the middle of a dense forest where even solar panels wouldn't be an option. And, if companies like Matrix can make it happen, these self-powered sensors could be the way toward making giant smart grids a reality in a super-connected future.

Watch this: Matrix and the vision of a self-powering smart universe

The technology discussed herein was previously reported by The Wall Street Journal in November, but I flew out to visit Matrix Industries to see the so-called "smart dust" technology for myself -- because I'm fascinated by the possibilities of not ever having to charge little gadgets again.  The company focuses on thermoelectrics to create a wave of "energy harvesting" gadgets and sensors that don't need replaceable batteries. (Yes, the company partially named itself after the Matrix movies, which turn 20 years old this year. And no, they're not looking to keep humans in vats.)

The company's newest inventions promise a future where networked sensors could exist in smart city grids, running on thermal energy alone. The little beacon canister is the prototype model for the PowerStation, a battery of sorts that can keep a low-power sensor running off the temperature differences in everyday weather conditions.


A look at the PowerStation at Matrix Industries' Menlo Park offices, and a phone app set up to see a sensor as a simulated beacon at a museum.

Angela Lang/CNET

I first met Matrix Industries' founders Akram Boukai and Douglas Tham a couple of years ago, when Matrix made its first unlikely product: a smartwatch powered by body heat. That device always seemed somewhat impossible at first pitch, and yet I wore one for weeks and it worked just fine. That watch used small temperature differences between skin temperature and ambient air to generate current -- just enough to run the watch's low-power processor and display.

The PowerStation is a different proposition, because it does similar things to the heat-powered smartwatch without needing to sit on a hot wrist. It can absorb differences in ambient air temperature, storing that heat over time in a substance the company calls "Luna Phase Change Material" and releasing the heat energy back later to power a sensor via electricity, like a battery.


A demo of the PowerStation, in the parking lot, set up to feel like a hiking trail (sort of).

Angela Lang/CNET

How much energy? Enough to power Bluetooth beacons, environmental sensors for weather or seismic vibration, or even smoke detectors or motion-controlled cameras, according to Matrix. The key is that the energy storage could be used in spurts as needed, releasing enough to briefly power higher-energy features.

"Any technology that may seem high power, as long as it's sleeping most of the time, you could continually recharge the battery and always keep it basically alive," Boukai explains. "We can even turn on antennas, use radios that transmit data to satellites, as long you're not doing it real time: maybe every 5 minutes, you could use thermoelectrics to do it."


Matrix hopes to make the cylindrical PowerStation as small as this metal cube.

Angela Lang/CNET

The PowerStation is a bulky cylinder right now, but Matrix is working on shrinking it down even smaller, to a small metal cube a few inches on a side. One of these boxes would be needed for each sensor or beacon, right now. Matrix claims the PowerStation can work outdoors from -10 to 50 degrees Celsius (14 to 122 degrees Fahrenheit) and up to 85 percent humidity in various temperature conditions and generate from 1 to 5 volts. Matrix is working to test the sensors in facilities, starting with a shipping container company in Pakistan and 3M in the US (3M is an investor in Matrix Industries).


A lineup of Matrix PowerStation prototypes, from a converted Thermos (left) to the goal size of the metal cube (right).

Angela Lang/CNET

Future refrigerators?

I walked past a couple of metal panels with fans attached. Tham told me it was an early prototype for a fast-cooling application of their thermoelectrics: A soda can-size container could fit in the middle of the triangle and super cool in less than a minute, like a microwave for cold. Tham and Boukai envision this being used, perhaps, in future gas stations or vending machines to fast-cool beverages as needed without spending money on larger refrigerators. "It could help in terms of cost savings, completely eliminate bulky compressors, and no CFCs," says Boukai.

The idea of thermoelectrics isn't new, but Matrix claims its energy-converting efficiency is what makes it work on all fronts. On a smaller scale, that's worked for its watch. Will it work as well on bigger, more power-hungry devices?


Matrix testing electrical conductivity of its thermoelectric material.

Angela Lang/CNET

Headphones and watches could run on solar, thermal energy and kinetics

At the moment, the energy output of Matrix's tech is limited from "several hundred microwatts to tens of milliwatts," says Boukai, but it's aiming to improve that. Solar energy is where Matrix is looking next, and the company's developing a new smartwatch to blend solar and body heat energy harvesting to show it can work to drive higher-powered tech.

"Today we're close to the Garmins and Suuntos of the world in terms of features," says Boukai. "Ideally, we'd be able to power an Apple or a Samsung , and the way we would do it is to incorporate energy harvesting beyond just thermoelectric. We envision thermoelectric, solar, vibration, maybe even RF, and all those combined together, in a very small package, I think can generate the amount of power required by those very energy-hungry devices."

Watch this: A solar and heat-powered fitness watch? Yes, please

Towards the end of my visit, Douglas Tham also said that future watch brands could end up featuring Matrix' heat-powered tech. Tham says it's not out of the question to power headphones, too, or even hearing aids: "We cannot confirm or deny that we may have a hearable in play at some point ... there are some very interesting developments in the processing side of things that we're aware of, and we're working with those guys on a solution to address that need," says Tham, although I saw no demonstrable proof of that working -- yet.


The company's PowerWatch X, which runs on body heat. The first version launched in 2017.

Sarah Tew/CNET

I'd like more self-powered things

I didn't know what to expect from my visit, and in some ways it's hard to judge how any of this actually works in the real world. But the vision is fascinating. For years, companies have promised vast networks of smart sensors knitting our world into a galaxy of beacons. Much of that world's already here, but if we're diving into a 5G and AR-enabled future where the real world becomes studded with sensors, how are they going to stay powered? Will it be by batteries, or by a rechargeable source of energy like solar, or thermal energy?

"You have these devices that rely today on coin cell batteries, and whether or not they last for six months to a year, if you really want to create a smart city and want to deploy millions of these, it'll be an awful expense and experience to go and replace millions of batteries," Boukai says. "We think we can use energy harvesting and thermoelectrics specifically to solve that battery recharge problem, so you can deploy as many sensors as you like and never worry about maintaining them."


How Matrix makes its conductive thermoelectric materials.

Angela Lang/CNET

That could be interesting for a growing wave of low-powered sensors needed in smart homes, smart cities and an increasingly connected smart world, even as a way of creating beacons to turn the physical world into a mapped landscape for augmented reality. Or, if a lot of little self-powered fitness sensors were worked into clothes and shoes (another area that Matrix hints at being explored), it could solve the need-to-charge problem in smart wearable clothing.

How fast that can happen remains to be seen. But if Matrix -- or any other company -- can crack that code, it could well mean a sea change for wearable tech and smart sensors as the calendar creeps to 2020 and beyond.

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