If there is ambient radio, you can also use that for extremely low power data transmission from your sensors. The trick there is to not actually transmit any of your own energy. You instead either absorb or reflect the ambient radio. This is called backscatter communications.
Here is a video showing a demonstration of both energy harvesting from ambient radio and backscatter data transmission [1].
If you use WiFi signals as your ambient radio for backscatter, the research group in that video has also demonstrated that you can make your backscatter data stream match standard WiFi protocols so that you can use ordinary WiFi equipment for the receiver.
The above was fairly short range, but even so there are a lot of interesting applications. For instance you might want to have moisture sensors inside a wall to detect water leaks early. If your sensors are powered by ambient EM energy (noise or radio), you don't have to limit the sensors to places where you can easily reach them later to change batteries. They are fine if they are behind brick or drywall with no openings.
If these devices can be built cheaply, just place them all over a factory, chirping their ID whenever they have enough power to do so. You map the IDs to locations and get a real-time map of where there's EM noise spitting out. When the map starts changing from it's usual patterns, then you identify the source of that change.
it’s hard to point at anything in the press release and confidently say “that’s new”. i think what’s happening is that IoT/sensing is a big enough market that companies can finally invest in engineering and commercializing some of the things that have been researched over the last several decades. which imo is great to see.
If you’re willing to sacrifice always on connectivity and have a node report in on an infrequent basis then I always figured EM harvesting would be the way to go for most applications since even a tiny amount of energy can build up over time to become a useful amount.
I knew I’d gone deep into this world when I started thinking that micro watts was a large amount of power!
It used energy-harvesting for the sensor packages, essentially charging caps if things got wet/moved/etc., but would boot up to do the sensor-data processing and communication (BLE/ANT) .. my lead on the project brought his dusty old home phone in, to give us all a stable power source, but we didn't really need it much - lots of 800mhz-900mhz in the city.
Was fun to realize, even back then, that we are literally surrounded by energy and don't really have an energy problem. We have an energy management problem, which we have yet to localize at the individual, and are instead spreading the problem across our society.
But, in between builds on this project, I would often daydream of a scenario where computing devices ran simply on background radiation, and there was no longer any need for cables, really, in order to compute.
Its fun to note we're getting closer and closer to that point. Okay, I could build a solar powered computer and also feel such satisfaction, but .. an all-in-one wafer that simply ran on cosmic noise?
Hell yeah, gimme that, sparkies!!!
That being said, it’s not the energy per se that we can tap into, it’s the gradient created as it dissipates/moves that we tap into. Heat is great, but not if it’s uniform, solar is great, but not if it harvesting it casts an area in shadow that needs it, vibration is great so long as it doesn’t damp and further load the system it’s being taken from.
(If you want to start a business off this idea feel free to contact me ;) half joking but half serious)
Also a question if such harvester need its own power source to be able to operate?
They cite a super wide range of EM freqs from Hz to MHz, and an efficient antenna...
Harvesters don’t need their own power supply and ideally the system can come back to life from totally empty (meaning it doesn’t need to be deployed with any charge level)
I was doing my thing back before the packaged harvester management chips were available and I made a PIC based microcontroller system that could monitor the charge level in a capacitor fed from a piezoelectric vibration energy harvester and decide when to wake up and transmit a data reading based on the capacitors charge level.
The trick was getting the PIC’s sleep current draw low enough that the capacitor was charging even at milli g level vibration levels - from memory you can get a PIC’s sleep current well down in the tens of nano amp range.
PICs have a built in voltage reference that is stable (a zener or schotkey diode from memory of 0.6V?) and a way to read what the Vsupply (basically the capacitor) is compared to it. So the PIC would wake up every 30 seconds, check Vsupply to the built in reference and, when high enough fully wake up, take and transmit a reading and go back to sleep.
From memory I got it running at 50mg transmitting every few minutes.
I got a nice journal publication in IEEE for that work.
I forget the minimum amount but so long as there was more than say 20 mG (milli-gravity) of vibration acceleration then it could harvest from empty.
It's the whole reason radio was invented.
If it were illegal, AM crystal radios would also have to be illegal. That's where radio all started.
Also, your phone harvests RF energy every time you charge it wirelessly with a Qi charger.
Lots of implanted devices are powered this way too
https://e-peas.com/product/aem13920-dual-source-energy-harve...
The Nexperia chips are also worth looking at, in that they translate high impedance sources to low enough to charge a cap:
https://www.nexperia.com/products/analog-logic-ics/power-ics...
https://www.nexperia.com/products/analog-logic-ics/power-ics...
The energy comes from the amplifier, it's being put into the ether by the woofer, and then the window pane collects it.
Energy is neither created nor destroyed.
The thing is, we don't have general purpose "windows" in this EM world, until now.
Thermal noise is not a tone, though.
- Harvesting from several dozen μW to several dozen mW of power.
- Harvesting from Hz to MHz freq EM noise
- 7x7 mm component footprint
I'm impressed; even though this idea isn't 100% new, the execution seems solid!
The second thing is the low frequency stuff. Its taught in most EE programs that you can use an antenna that is tuned to a frequency to transfer energy wirelessly from xmitter to receiver (see NFC or RFID) but antennas that tune sub-MHz frequencies are typically quite long in order to have some level efficiency. That they do this by exploiting geometry of various conducive elements and get enough energy is super impressive too.
If you followed the old BEAM stuff[1] that Mark Tilden promoted, you could see some ideas about two-phase devices that live in a "collect" phase charging up an energy reservoir and then an "execute" phase where they dump that energy doing their thing. BEAM was focused on robotics and bug like behaviors but there is no reason you couldn't have a sensor that measures temperature and humidity and transmits that to a receiver somewhere. Or a passive "game" camera that, once it has collected enough energy, takes a snapshot when it detects motion and sends that along.
I'll be interested to see this stuff get commercialized and designed in. It does have shades of "Smart Dust"[2] though which is pretty ripe for abuse.
What a great point of entry into robotics and hardware design it was for a whole generation of engineers and roboticists. It provided a very low cost (it was encouraged that the parts for these robots came from old broken electronics. They were also super simple designs which were explained in great detail, very well. This combination made for a very good education in the foundations of robotics, engineering, mechatronics, hardware and system design, etc.
BEAM, the Parallax Basic Stamp, the Tandy 1000RLX, and the RB5X robot and the summer classes I took with the makers the RB5X all had a huge impact on my ability to architect, design and build robots professionally.
But at the same time I can't understand how such a thing works using pure white noise. Feynman famously described (and disproved) a similar energy-harvesting device [0] except one that uses mechanical noise and a mechanical rectifier instead of the electrical noise and electrical rectifier of Sony. He showed that such a device will eventually stop working due to the second law of thermodynamics. Why doesn't that happen in the Sony chip?
