4 ms·

Unlike Theranos which had a lot of non-VC investors uBeam had some of the best. Sound travels in a wave and energy would dissipates exponentially with distance.

Unlike Theranos which had a lot of non-VC investors uBeam had some of the best. Sound travels in a wave and energy would dissipates exponentially with distance. It made no sense to me how this would work or why these investors got behind this. Insight would be appreciated.

Afrotechmods 8y ago
Back when this first started Meredith built a "prototype" in a couple of days which, to a layperson, would appear impressive. There was a function generator with an amplifier sending out ultrasound via an array of transmitters and about a meter away there was an array of receiving transducers that picked up the utlrasound. Then the output from those receiving transducers was rectified with a few diodes to get DC. In this demonstration she had a multimeter showing the voltage at the receiving side, and when she tweaked things just right, she received 5 volts on the receiving side. 5 volts is the standard voltage you'd use to charge a phone, or any other USB powered device, so it was reasoned that she had created a viable system that could charge phones wirelessly. The problem is that any idiot can get 5 volts out of thin air. You can literally hang up a long bare wire and rectify ambient radio waves and get 5 volts. The trick is getting 5 volts and being able to supply significant amounts of current at the same time i.e. receiving useful amounts of _power_. Power = Volts x Amps and Meredith and her investors simply did not understand the importance of this equation that a freshman in engineering would understand. FOMO kicked in and they threw millions of dollars at her thinking it was going to be the next big thing.
- baud147258 8y ago
  > a freshman in engineering would understand I don't even think that as a freshman, I would have gotten it. On the other hand, I was pretty loosy on the EM side of things, that's why I then went into software quickly afterward .
- illiac_1962 8y ago
  Wow, so she generated a shitload of charged air and used a child's science experiment to woo some VCs? I think I'm in love. I cannot stop laughing. She could get rich many times over pulling this trick.
  - foldr 8y ago
    > a shitload of charged air No, the air isn't holding a charge in Meredith's setup. The setup is essentially a speaker and a microphone, but optimized (somewhat) for energy transmission.
2_listerine_pls 8y ago
> Sound travels in a wave and energy would dissipates exponentially with distance It's actually possible to transmit sound waves without the exponential decay with "directional sound" [1]. It is produced using a "phased array" [2] of speakers, where each speaker has a different a phase. The point is to create constructive interference in the direction you want the sound beam. Directional speakers have existed for a while and that's probably how uBeam emitters work. [1] https://en.wikipedia.org/wiki/Directional_sound https://en.wikipedia.org/wiki/Directional_sound [2] https://en.wikipedia.org/wiki/Phased_array https://en.wikipedia.org/wiki/Phased_array
- deepnotderp 8y ago
  Repeat after me: directional radiation is still subject to inverse square law.
  - danielvf 8y ago
    Agreed in the general case, but what about a laser?
  - Trevor908 8y ago
    Only in the far field.
- URSpider94 8y ago
  1. The size of the phased array is directly related to the distance over which you want to maintain focus. In order to focus a beam across a room, you need a hilariously large array. 2. Ultrasound transducers are very inefficient, so you’ll lose a lot of power. 3. Ultrasound transmission will be blocked by a person, or even by a sheet of paper in the way. 4. Even if you do achieve a tight beam, then you either have to actively steer it around, or it’s only good for transmitting power to something sitting still in a specific spot. 5. We don’t really know much about the effects of having watts of ultrasound present in a space with humans 24/7/365. (And these are just the easy ones)
  - tzs 8y ago

Afrotechmods 8y ago

Back when this first started Meredith built a "prototype" in a couple of days which, to a layperson, would appear impressive. There was a function generator with an amplifier sending out ultrasound via an array of transmitters and about a meter away there was an array of receiving transducers that picked up the utlrasound. Then the output from those receiving transducers was rectified with a few diodes to get DC. In this demonstration she had a multimeter showing the voltage at the receiving side, and when she tweaked things just right, she received 5 volts on the receiving side. 5 volts is the standard voltage you'd use to charge a phone, or any other USB powered device, so it was reasoned that she had created a viable system that could charge phones wirelessly. The problem is that any idiot can get 5 volts out of thin air. You can literally hang up a long bare wire and rectify ambient radio waves and get 5 volts. The trick is getting 5 volts and being able to supply significant amounts of current at the same time i.e. receiving useful amounts of _power_. Power = Volts x Amps and Meredith and her investors simply did not understand the importance of this equation that a freshman in engineering would understand. FOMO kicked in and they threw millions of dollars at her thinking it was going to be the next big thing.

baud147258 8y ago
> a freshman in engineering would understand I don't even think that as a freshman, I would have gotten it. On the other hand, I was pretty loosy on the EM side of things, that's why I then went into software quickly afterward .
illiac_1962 8y ago
Wow, so she generated a shitload of charged air and used a child's science experiment to woo some VCs? I think I'm in love. I cannot stop laughing. She could get rich many times over pulling this trick.
- foldr 8y ago
  > a shitload of charged air No, the air isn't holding a charge in Meredith's setup. The setup is essentially a speaker and a microphone, but optimized (somewhat) for energy transmission.

2_listerine_pls 8y ago

> Sound travels in a wave and energy would dissipates exponentially with distance It's actually possible to transmit sound waves without the exponential decay with "directional sound" [1]. It is produced using a "phased array" [2] of speakers, where each speaker has a different a phase. The point is to create constructive interference in the direction you want the sound beam. Directional speakers have existed for a while and that's probably how uBeam emitters work. [1] https://en.wikipedia.org/wiki/Directional_sound https://en.wikipedia.org/wiki/Directional_sound [2] https://en.wikipedia.org/wiki/Phased_array https://en.wikipedia.org/wiki/Phased_array

deepnotderp 8y ago
Repeat after me: directional radiation is still subject to inverse square law.
- danielvf 8y ago
  Agreed in the general case, but what about a laser?
- Trevor908 8y ago
  Only in the far field.
URSpider94 8y ago
1. The size of the phased array is directly related to the distance over which you want to maintain focus. In order to focus a beam across a room, you need a hilariously large array. 2. Ultrasound transducers are very inefficient, so you’ll lose a lot of power. 3. Ultrasound transmission will be blocked by a person, or even by a sheet of paper in the way. 4. Even if you do achieve a tight beam, then you either have to actively steer it around, or it’s only good for transmitting power to something sitting still in a specific spot. 5. We don’t really know much about the effects of having watts of ultrasound present in a space with humans 24/7/365. (And these are just the easy ones)
- tzs 8y ago