5 ms·

Really not sure what they are trying to get at here, but their "usable energy" is on the pico-watt to micro-watt scale. It looks more and more like one of those

Really not sure what they are trying to get at here, but their "usable energy" is on the pico-watt to micro-watt scale. It looks more and more like one of those "free energy" type devices. Edit: Yes I understand that there is energy in RF signals, I am just questioning the actual practicality and claim that they can get usable energy from this. For a 200 mW (23 dBm) WiFi transmitter the free space loss at about 6 inches is 23 dB at which point you would have the same 0 dBm input that they used in the experiment. I have not included any antenna gain as they did not include the antenna gain from their microstrip patch antenna in their experiment, just the 0 dBm power input number.

giuliomagnifico 5y ago
The device can receive: > For the condition of synchronization of four oscillators at 2.4 GHz with Idc,sync = 3 mA (1.2 mA) for the parallel (series) configuration That’s very low but I think a first step in order to power small biometric implants, for example some kind of pacemakers. It’s very frustrating have a surgical operation to change the battery every 10/15 years.
- nycdotnet 5y ago
  Would be an ironic way to power a pacemaker as you'd be asked to start standing near the microwave.
  - giuliomagnifico 5y ago
    Ahah that’s true, because some pacemakers send datas to the receiver/hospital through 2.4ghz band, so it can have interferences. But mine was only an example because my father has one of those device into his body and sooner or later it will need a “battery swap”. Maybe not a pacemaker but to power a small temperature sensor, or something similar, it will be useful, send datas and get energy, quite nice and futuristic!
- dr_orpheus 5y ago
  The current you refer to there is not the power that is being generated though, it seems to be an input in to the STO devices. > The STOs are connected in parallel (Fig. 1a) or in series (Fig. 1b) configuration, stimulated by a single dc source. For the parallel connection, at the dc bias (Idc) value of 1.5 mA Fig 2c and d shows the total output power which maxes out at 0.85 uW. Maybe this is enough to run a pacemaker or something small, I don't actually know. Fig 6 shows the rectification of the signal in to a voltage that can turn on an LED. The dc-dc converter puts it in the ~3V range. Assuming the dc-dc converter is near 100% efficiency (some are pretty damn good) this is a current of only 0.28 uA. Its a novel way, but they talk about in their own paper that it is not a new more efficient way to convert RF energy to DC energy > in the range of 1.65–2.8 GHz at Prf = 0 dBm and zero dc bias ac to dc conversion efficiency of ∼6% at Prf = −20 dBm. This is higher than the reported values for STOs53,55 but less than the recent reports of power conversion efficiency of 40% and 40–70% at an input rf power ~0 dBm for MoS2-based flexible rectenna and state-of-the-art Si and GaAs rectifiers56
sigstoat 5y ago
> their "usable energy" is on the pico-watt to micro-watt scale devices which have long-term average power consumptions of micro-watts are perfectly reasonable. it's how some BLE sensors can run for years off a single coin cell battery. you'd need some energy harvesting circuitry and something low-leakage to build it up in, but that's doable. more expensive than just stuffing a coin cell into the circuit, though. > It looks more and more like one of those "free energy" type devices. it's perfectly well understood that there's energy in RF. just very very little of it, as you note. that's qualitatively different from the claims of most free energy devices.

giuliomagnifico 5y ago

The device can receive: > For the condition of synchronization of four oscillators at 2.4 GHz with Idc,sync = 3 mA (1.2 mA) for the parallel (series) configuration That’s very low but I think a first step in order to power small biometric implants, for example some kind of pacemakers. It’s very frustrating have a surgical operation to change the battery every 10/15 years.

nycdotnet 5y ago
Would be an ironic way to power a pacemaker as you'd be asked to start standing near the microwave.
- giuliomagnifico 5y ago
  Ahah that’s true, because some pacemakers send datas to the receiver/hospital through 2.4ghz band, so it can have interferences. But mine was only an example because my father has one of those device into his body and sooner or later it will need a “battery swap”. Maybe not a pacemaker but to power a small temperature sensor, or something similar, it will be useful, send datas and get energy, quite nice and futuristic!
dr_orpheus 5y ago
The current you refer to there is not the power that is being generated though, it seems to be an input in to the STO devices. > The STOs are connected in parallel (Fig. 1a) or in series (Fig. 1b) configuration, stimulated by a single dc source. For the parallel connection, at the dc bias (Idc) value of 1.5 mA Fig 2c and d shows the total output power which maxes out at 0.85 uW. Maybe this is enough to run a pacemaker or something small, I don't actually know. Fig 6 shows the rectification of the signal in to a voltage that can turn on an LED. The dc-dc converter puts it in the ~3V range. Assuming the dc-dc converter is near 100% efficiency (some are pretty damn good) this is a current of only 0.28 uA. Its a novel way, but they talk about in their own paper that it is not a new more efficient way to convert RF energy to DC energy > in the range of 1.65–2.8 GHz at Prf = 0 dBm and zero dc bias ac to dc conversion efficiency of ∼6% at Prf = −20 dBm. This is higher than the reported values for STOs53,55 but less than the recent reports of power conversion efficiency of 40% and 40–70% at an input rf power ~0 dBm for MoS2-based flexible rectenna and state-of-the-art Si and GaAs rectifiers56

sigstoat 5y ago

> their "usable energy" is on the pico-watt to micro-watt scale devices which have long-term average power consumptions of micro-watts are perfectly reasonable. it's how some BLE sensors can run for years off a single coin cell battery. you'd need some energy harvesting circuitry and something low-leakage to build it up in, but that's doable. more expensive than just stuffing a coin cell into the circuit, though. > It looks more and more like one of those "free energy" type devices. it's perfectly well understood that there's energy in RF. just very very little of it, as you note. that's qualitatively different from the claims of most free energy devices.