1.  What’s an Evercell™?

Evercell™ power cells by Evergreen® Technologies, LLC – one of The Face® Companies – are passive-structure, semiconductor-based thermal energy harvesters that produce a small, continuous flow of electric power in virtually any environment where the temperature is above absolute zero. They will therefore eliminate the need for batteries in a broad array of low-power sensors, embedded circuits and wireless communicating devices. These patented and patents-pending power cells consume no fuel, have no moving parts, contain no toxic materials, and require no exposure to other external stimuli, including motion, pressure, RF, visible light or other electromagnetic energy.

 

2.  Will Evercell™ actually work?

It’s already working. An Evercell™ demonstrator has been operating nonstop at Face Companies headquarters since October 2016, generating a continuous flow of electric power with no reduction in performance over time. Another has operated flawlessly while frozen in a block of ice.

 

3.  Are you sure you haven’t just inadvertently created a battery?

A logical question, but independent scientists have confirmed that Evercell’s™ component materials couldn’t possibly function as a battery.

 

4.  Doesn’t Evercell™ violate the second law of thermodynamics?

It might appear to, but the law must be understood in the context of certain recently observed phenomena at the quantum level – phenomena that Evercell™ exploits.

About 150 years ago, the physicist James Clerk Maxwell offered a thought experiment imagining a “demon” that could somehow sort the particles in a gas according to their differing speeds, or temperatures. By sending the more energetic (warmer) particles to one region and the less energetic (cooler) particles to an opposing region, the demon could generate electricity.

As the American Physical Society noted in 2015, “At first sight, [Maxwell’s] demon appears to violate the second law of thermodynamics. But the paradox can be resolved by realizing that work must be performed on the demon for it to do its job …” And, until very recently, physicists have routinely dismissed Maxwell’s idea as irrelevant for practical purposes because separating the particles into warmer and cooler zones would require more work-in than the energy-out that the resulting system could produce.

Evercell™, however, is a passive system, requiring no energy-in except for ambient heat, and will continue to run indefinitely in virtually any environment warmer than absolute zero. Simply by having its engineered materials layered and arranged in a particular way, the Evercell™ promotes the release of electrons from one conductor surface toward another through the phenomenon of quantum tunneling. Thus it can be accurately described as an autonomous demon.

 

5.  Can you cite some supporting research?

Yes. A theoretical physicist at the Los Alamos National Laboratory, Sebastian Deffner, whose research focuses on quantum thermodynamics, has cited recent experimentation at Finland’s Aalto University that produced results “explicitly showing that autonomous demons can exist and are not just theoretical exercises.” Dr. Deffner notes “[t]his doesn’t mean that the second law is breakable, but rather that physicists need to find a way to carefully formulate it to describe specific situations.”

The research to which Dr. Deffner refers was reported in Physical Review, the most prestigious journal in physics. The white paper describes a different type of harvester – not Evercell™ – but it documents that physicists who specialize in quantum thermodynamics have demonstrated that something like Evercell™ can exist. And that is a milestone development.

Links to additional relevant research are provided on our Technical Documentation page.

 

6.  How does Evercell™ work? What’s the energy harvesting mechanism?

The Evercell™ harvests thermal energy in environments with no perceptible thermal differential. Each component or constituent element has a passive four-layer structure made of specially engineered materials. Opposing electrodes, one being surface treated to lower the work function of its facing surface, are placed in close proximity, sandwiching a dielectric layer with a thickness of 200nm or less. Based on the designed difference in work function of the opposing electrode surfaces, electrons migrate away from the surface of one of the electrodes and accumulate near the surface of the other electrode, thereby establishing an electrical potential in the cell.

 

7.  What do you mean by “work function” here?

Work function is the energy, usually specified in electron volts (eV), that is needed for an electron to leave a surface of a material. In solid-state physics, the work function is the minimum thermodynamic work (i.e., energy) needed to remove an electron from a solid to a final electron position remote from the surface on the atomic scale. The work function is not a characteristic of the bulk material but rather a property of the surface of the material.

 

8.  Are there other structural factors important to Evercell’s™ operation?

The proximity (<200nm) of the opposing surfaces is critical, because it promotes quantum tunneling of electrons from the surface with the lower work function to the opposing surface with the higher work function.

 

9.  What is the potential electrical power-out of an Evercell™?

At this early stage, we’re unsure what the upper limit may be. Individual Evercell™ modules can be connected in series and in parallel, as necessary. Here are some examples of expected performance for first-generation production devices:
• 5μW device: 34mm X 34mm X 1mm — 1.2V output, 4.2μA continuous current
• 960nW device: 50mm X 75mm X1mm — 1.2V output, 800nA continuous current
• 480nW device: 30mm X 305 mm X2mm — 1.2V output, 400nA continuous current

 

10.  Can Evercell™ really be used as a battery substitute?

Yes, with an appropriate interface circuit, there are many applications where Evercell™ will be the preferable alternative to batteries, such as powering wireless sensors and communications nodes in the Internet of Things. Up to now, based on the assumption that there’s no substitute for battery power for most wireless devices, the focus of research and innovation has been to reduce the device’s power requirements, thus extending the life of the battery. Ironically, this steady reduction of power need has opened the way for Evercell™ and the elimination of batteries in billions of cases.

 

11.  How big an impact could this have on the Internet of Things?

In the fall of 2017, before the invention of Evercell™ was publicly revealed, the world’s leading analysts of the IoT’s potential for growth and proliferation were reported by IDTechEx to have estimated that the potential population of IoT devices would be five times larger if a viable substitute for batteries could be identified. As Evercell™ becomes available, it will open the possibility of embedding wireless sensors within the concrete of bridges and dams, or placing them in remote or hostile environments where the cost of changing batteries would be acceptably high, or implanting them in patients to power medical devices.

 

12.  Medical devices?

Yes, although deployment could take a while because of the government approval process, the potential medical applications of Evercell™ are extraordinary. Since Evercell™ can provide a non-chemical, non-toxic, bio-neutral source of power that won’t run down, one can easily foresee its use within the human body, driving monitor or stimulator devices. Compare this, for example, with a conventional heart pacemaker, where surgery is required to change the battery.

 

13.  How is Evercell™ fabricated?

To make an individual Evercell™ element, a first conductor layer for the donor surface is formed on a substrate. The donor surface of the conductor layer is conditioned to reduce its work function to be in a range of 1.0eV or less. A dielectric layer, with a thickness in a range of 200nm or less, is deposited on the first conductor layer using any one of a number of conventional layer deposition methods. A second conductor layer formed of a material to present a facing surface with a work function in a range of typically 2.0eV or greater is then formed on the dielectric layer. Layered elements formed in this way may then be stacked, with insulating layers interposed between them, and may be interconnected in series or in parallel as needed to meet voltage and current-out requirements. Each of the individual layered elements may be multiples of tens of nanometers thick, and may be sandwiched between insulating layers, each of which may be on the order of 10µm thick. The resulting Evercell™ device, including a stack of 50+ insulator-separated layered elements surrounded ultimately by an outer insulating shell, may have a total thickness in a range of 50 mils or less. So, for example, integrated circuit elements could be configured to be individually self-powered.

 

14.  It must be expensive to make.

No, Evercell™ is made from readily available materials, and existing semiconductor production lines can be readily retooled to produce it. Once mass production is achieved, cost per unit is likely to be somewhere in the range of the battery being replaced.

 

15.  Are there any toxic materials?

No, Evercell™ manufacture involves no toxic materials, and its production of energy is not dependent on any chemical reaction. So, unlike a conventional battery, Evercell™ is environmentally safe to make and operate, and to dispose of at the end of the service life of the sensor or other device that it powers. This, along with the elimination of the requirement for routine replacement, makes Evercell™ a very attractive battery substitute and expands the range of deployment options well beyond what’s achievable with battery power.

 

16.  How’s your patent protection?

Very good. We have multiple issued U.S. patents for this technology, plus additional patents expected to issue within months, plus more pending in the U.S. and other countries. Our patent counsel is ensuring that we have overlapping coverage for every aspect of the technology and for various identified “use cases.”

 

17.  When will Evercell™ be commercially available?

We began negotiating licenses to manufacture and use Evercell™ in 2019, but because of the global pandemic, we now expect it to be commercially available in 2023.

 

18.  So, can you recap Evercell’s™ advantages?

• Evercell™ will enable small wireless sensors and controls in the IoT and elsewhere to operate without batteries for the life of the device.
• It provides continuous output without a perceptible temperature differential in essentially any environment above absolute zero.
• Its structure is solid-state.
• Its output is scalable and it can be made in various form-factors.
• It relies on no toxic materials in its production or operation, and can therefore reduce the environmental hazards presented now by batteries.
• It will be inexpensive to manufacture once mass-production is established.
• It leverages existing semiconductor manufacturing processes.
• It will enable the design of self-powered integrated circuits for the IoT.