Re:Ultrasonic Power Transfer Investigated Using Data from uB...
by Someone on Tuesday October 20, 2015 @06:17PM
(#10422216)
Orders of magnitude, for me, starts at 1.5 log unit. That would make it ~15% charge overnight, assuming 100% power transfer efficiency.
Let’s read a bit more:
”the power levels beamed are more than 50 times lower than the lowest ultrasound imaging exposure limits set by the FDA for medical imaging”
The lowest limits I could find in http://www.fda.gov/RegulatoryInformation/Guidances/ucm070856... is 20 mW/cm^2 (“A simple conservative approach for pulsed Doppler FHR monitors is to use 20 mW/cm2 as a guide for the maximum spatial-average pulse-average intensity at the transducer face”)
Dividing by 50 for the ”more than 50 times lower than the lowest ultrasound imaging exposure limits”, and multiplying for (ballpark) 100 cm^2 receiver area (about what one can get in a mobile phone), I get 40 mW of power received.
Let’s read a bit more:
”the power levels beamed are more than 50 times lower than the lowest ultrasound imaging exposure limits set by the FDA for medical imaging”
The lowest limits I could find in http://www.fda.gov/RegulatoryInformation/Guidances/ucm070856... is 20 mW/cm^2 (“A simple conservative approach for pulsed Doppler FHR monitors is to use 20 mW/cm2 as a guide for the maximum spatial-average pulse-average intensity at the transducer face”)
Dividing by 50 for the ”more than 50 times lower than the lowest ultrasound imaging exposure limits”, and multiplying for (ballpark) 100 cm^2 receiver area (about what one can get in a mobile phone), I get 40 mW of power received.
http://www.fda.gov/downloads/MedicalDevices/DeviceRegulation... gives 17 mW/cm^2 for ophthalmic use, so 20 mW/cm^2 isn’t even strictly the lowest limit set by the FDA.
There may be a useful product here, but if so, I don’t see how all of what they say can be true.