4 ms·

Interesting. That OV06948 camera is also 40k (200x200) pixels, 30fps, and RGB. Critically, the page you link lists its weight at 0.87g = 870mg, which would make

by tofof 6y ago

Interesting. That OV06948 camera is also 40k (200x200) pixels, 30fps, and RGB. Critically, the page you link lists its weight at 0.87g = 870mg, which would make it 157x denser than lead.[1] The actual spec sheet says 0.87 mg, i.e. less than one milligram, which is incredible.[2] It has up to a 4 meter range, which I understand to be wired, so it would still need some sort of transmitter. The camera used by these researchers, including its lens and panning head, is 200 mg (77 for the sensor and lens and mount, 7 mg bluetooth chip, and 96 mg boost converter). It's only 20k (160x120) resolution, monochrome. It has a wireless 120 m range. The killer, however, seems to be power. The 10 mAh battery alone weighs 500 mg, which means the 200 mg vs <1 mg comparison becomes more like 700 vs 501. The OV06948's power usage is 25 mW, which means a 10 mAh / (25 mW / 3.3 V) = 1.32 hour runtime, capturing 142k frames of video. The bug rig gets 6 hours, capturing only 108,000 frames of video. Perhaps you could get longer battery life out of the OV06948 if you slowed the framerate. [1] https://www.wolframalpha.com/input/?i=%28870+mg+%2F+%280.65+mm+x+0.65+mm+x+1.158mm%29%29+%2F+density+of+lead https://www.wolframalpha.com/input/?i=%28870+mg+%2F+%280.65+... [2] https://www.ovt.com/download/sensorpdf/553/OmniVision_OVM6948.pdf https://www.ovt.com/download/sensorpdf/553/OmniVision_OVM694...

zaroth 6y ago
Unfortunately this seems outside the bounds for ambient RF energy harvesting, even if you don’t mind dropping a few frames to charge back up if the capacitor runs low. The rectenna would have to be much too large to produce anywhere near 25mW even at a 10% duty cycle. I suppose if you didn’t mind ramping the RF output power way up you could shrink the antenna size, but not much smaller than 1cm^2 I think.

by tofof 6y ago

zaroth 6y ago

Unfortunately this seems outside the bounds for ambient RF energy harvesting, even if you don’t mind dropping a few frames to charge back up if the capacitor runs low. The rectenna would have to be much too large to produce anywhere near 25mW even at a 10% duty cycle. I suppose if you didn’t mind ramping the RF output power way up you could shrink the antenna size, but not much smaller than 1cm^2 I think.