MEMS Gyroscopes, Smartphones, and Ultrasound

This morning I was reading an article on Ars Technica (great tech website if you don't already read it) about the use of "sonic guns" to disrupt the operation of electronics and gadgets like drones. Here's a simple demonstration video of this happening.

As you can see the toy robot, which balances due to the gryoscopes in it, is quickly confused by the incident sound and ends up moving, then falling over. Why does this happen?

MEMS gyroscopes are Micro-Electrical-Mechanical Systems, essentially a very small structure that's often made by the same processes used to build computer chips, that has combined electrical and mechanical behaviors that are useful to us. In the case of a MEMS gyro, it leads to motion that creates an electrical signal which can be processed to determine rotation. These structures are small enough to be packaged into something smaller than your fingernail, and so can be fitted into compact spaces and consumer goods. Here's a video of a very simple MEMS gyro oscillating.

An image below from UC Davis MEMSLab shows how one small device can detect rotation in all three axes.

You can see that each sensing mode here has at least one "resonant frequency" at which the device naturally oscillates, which means it is very very sensitive to those frequencies. Like finding the right pitch for a glass, you can actually break them by causing them to vibrate at that frequency. Some work here, here, and here shows in more academic detail how the MEMS gyros can be rendered ineffective by ultrasound above around 100 dB. Sound is, after all, just a vibration at a particular frequency - match that sound to the resonant frequency of the gyro and it will play havoc with it.

Here's a drone showing the effect of ultrasound on its behaviour - notice that the transducers used to generate the ultrasound look like Murata devices, very similar in appearance to what uBeam look to be using in their transmitters. (I appreciate the safety precautions this researcher took!)

What this all seems to be pointing to is that high powered ultrasound in the environment can disrupt the activities of more and more of our devices such as drones - what happens if they fly through a high power ultrasound beam? Do they veer off and hit someone? And the smartphones we all use today? Those phones have multiple MEMS sensors in them, and the gyro is what allows you to play games just by tilting your phone. What happens when you direct ultrasound at levels far greater than 100 dB towards a smartphone? The manufacturers know, they spend a lot of time making sure that nothing in the phone vibrates at frequencies that disrupt their operation, but I'm not sure I've seen a study that's been made public.

Those may seem like simple examples, but there are safety considerations. What happens if a safety related system, such as positioning in a vehicle, is disrupted by high power ultrasound? Who is responsible for that? Cars and larger objects can usually shield the gyro to insulate the sound from it, but what about size and weight sensitive devices like smartphones?

If the videos above give an indication, then truly ubiquitous high power ultrasound in the environment is going to be disruptive in more ways than one. Just as well no-one is likely to try to put such loud ultrasound devices out there en-masse.

Dunkirk

Movie review: Dunkirk

Basically - go see it. Great movie. No - fantastic movie. I've found Chris Nolan to be hit or miss - always beautifully filmed, but there are often plot holes you can drive a bus through that most people seem to miss because it all looks so good, and so much is thrown at you that you're overloaded. Inception and The Prestige are the two worst examples of this (so bad I've watched them twice..) while Interstellar has ridiculously awful science it pretends to adhere to, until halfway through it shifts to a "love conquers all" mode and rapidly descends to a giant cauldron of liquid poo in which it revels. Memento gets it right, sticking with a single theme and follows it through, while the first two Batman films are just brilliant (followed by an entertaining but not-as-good third).

Nolan loves to play with time in his films - Inception with its layers and ticking clock, Interstellar with the time dilation due (and ticking clock), Memento and the forward/backward storyline. He does the same in Dunkirk, with three storylines of a week, a day, and an hour in the lives of several Dunkirk participants, all intersecting in parts as they grow closer and closer together - and all through it, a ticking clock (literally) as the soldiers desperately try to get home.

I don't often get drawn in to films, but I found myself tense throughout, and Nolan manages to bring in a lot of tension as you sit on edge waiting for the next thing to go wrong. It's an exhausting film. More though, it gets over the utter powerlessness of almost all the participants, that they're simply statistics and at some point people are going to die, no matter their skill or preparation. This isn't an Arnie action film where the hero saves the day, this is about the horrors of war and how small and insignificant each person is, but also the intense bravery of many of these men in ways that no-one ever would know.

There's a Marie-Claire contributor who has been talking about how it's just a film glorifying war for men. Yeah, this glorifies war like Trainspotting glorifies taking drugs. It's hideous from nearly 80 years away.

As we exited the film, my wife recounted some stories of her grandfather, who was at Dunkirk. She had interviewed him as part of a school project. He was a remarkable man, I met him when he was in his early 90's, and I would have guessed he was in his 60's. Born in 1912, grew up in a children's home, joined the army when 18, served until the end of WWII, started a welding business then sold it and retired at 65 - got bored and started another one at 67 and ran it until he was 89. He didn't talk about what he did in the war, he even gave all his medals to a local museum to the horror of his family, as he thought no-one would care.

As part of this interview, he described running through the streets towards the beaches at Dunkirk, with men feet away from him being shot dead, and waiting for the evacuation. He was told he was brave but he said he never felt brave, all he did was try to survive. And that, in the end, was much of the point of the film, that these men survived and then later went back to fight again, that these seemingly small acts of what they couldn't see as bravery, mattered.

It also made me think of my wife's great uncle. He was on board the Royal Oak, a British battleship sunk by the Germans at the onset of WWII. Of the ~1200 crew, 833 were killed when it was torpedoed in Scapa Flow at the naval base in Orkney - her uncle, Billy, was one of the men killed. He was 16. Like the Arizona at Pearl Harbor, this site is now a war grave, and we were allowed to scatter the ashes of Billy's sister there. She never got over the loss of her brother. Another young man who tried to do what he could and serve, yet died almost the moment it began. The film reminded me that great feats aren't required to be a hero, that simply volunteering for a role that puts you in harms way for a greater good does that.

All that, so well filmed, and perfectly acted by every one of them, especially Tom Hardy. Never overplayed, just done right.

I'm not sure I've seen a film that conveys the horror and randomness of war, along with the personal sacrifice and bravery of the men who served.

Go see it.

Mount St. Helens National Monument and the US Forest Service

I just spent yesterday at the Mount St Helens National Monument, and wanted to recommend it to anyone who passes through southern Washington or northern Oregon. Not to be missed, the US Forest Service do a great job of keeping it maintained, accessible, and making it educational.

Their budget is around $5.5 billion, which sounds a lot but there are a few things to consider - the maintain nearly 200,000,000 acres of public land (mowing my 0.1 acres of lawn is pain enough...) and nearly 400,000,000 acres of private land, manage forestry and mineral extraction, and then the most visible part to the public - keeping lands and national monuments open and available for education and recreation. That results in an estimated ~$35 billion of economic activity such as tourism. Seems a pretty good return on investment for the country.

Amazingly, half of that budget is spent fighting fires, so when you hear the calls for eliminating various agencies and reducing their budgets, remember that a lot of these agencies are a victim of their own success. Perhaps they should let a few towns burn down now and then to remind people that forest fires can be bad...

I'm only half joking there, because 20 years ago the cost of fire fighting took up 1/6th of their budget and it's been rapidly increasing since. They estimate it's going to double again in the next 30 years.

Changing climatic conditions across regions of the United States are driving increased temperatures— particularly in regions where fire has not been historically prominent. This change is causing variations and unpredictability in precipitation and is amplifying the effects and costs of wildfire. Related impacts are likely to continue to emerge in several key areas: limited water availability for fire suppression, accumulation at unprecedented levels of vegetative fuels that enable and sustain fires, changes in vegetation community composition that make them more fire prone, and an extension of the fire season to as many as 300 days in many parts of the country. These factors result in fires that increasingly exhibit extreme behavior and are more costly to manage. 

The six worst fire seasons since 1960 have all occurred since 2000. Moreover, since 2000, many western states have experienced the largest wildfires in their state’s history. 

In addition, more and more development is taking place near forests—an area referred to as the WildlandUrban Interface (WUI). Increasing densities of people and infrastructure in the WUI makes management more complex and requires more complex and requires more firefighting assets to ensure an appropriate, safe, and effective response that protects lives and property.

We're living with an administration that's trying to remove national monuments, sell off public lands to private only use, and is slashing budgets for departments like this - the FY2018 budget looks to be reduced by nearly $1 billion. The service keeps up with the firefighting - it has no choice - but this is at the cost of deferred maintenance and reducing other activities which support the land and recreation. At some point, this is going to the the US Forest Firefighting Service, and that's all. It may seem a minor thing when we're dealing with other major, immediate, crises, but the US Forest Service provides a critical function for our country, and we need to support it.

On a happier note, the trip into the Mt St Helens Monument was fun. Stop at the visitors center about 5 miles in from I-5 for the educational side, then drive up about 50 more miles to the observatory for some fantastic views of the volcano.

There are a ton of trails and other parts of the monument to access, we barely scratched the surface. Try and go if you're ever in this part of the world, and support the US Forest Service whenever you can, we all rely on them for way more than most realize.

Picking on the Little Guy

If you don't like politics, stop reading. For those who have to live in this world...

Anytime a politician or those in power target the poor, the powerless, minorities, and those who have no means of defending themselves, then take a close look because they are most likely either looking for a scapegoat or trying to deflect and distract from something else. 

No-one should be singled out based on gender, sexual orientation, religious choice, race, socio-economic class or anything similar. Any country that is diverse in its population and works to integrate, not separate, will be stronger because of it. Moreover, a country that looks after the weakest of its citizens is a society that will be just to everyone.

Authoritarian regimes get their start with scapegoats from small groups outside the mainstream. We should have zero tolerance for any such discrimination from our government. The recently tweeted 'trans ban' is exactly such an action. If someone meets the physical and mental requirements for the military, or any other role, they should not be discriminated against.

As an example you have likely already seen, I give you Kristen Beck, a transgender Navy SEAL. Kristen seems like exactly the type of warfighter we want, and wouldn't let things like 'bone spurs' get in the way of serving. Her quote sums up the entire situation perfectly:

It's a leadership issue, not a transgender issue.

America is better than this, and such divisiveness can't be allowed to stand. What is happening right now is not normal, and we can't allow it to become that way. To those who don't care about such people, let me make this pretty clear - Donald Trump doesn't care about you, or your tax cuts, or your coal mining job, or whatever you thing you can get from dealing with the devil, and one day you will be the target, no matter how white or male or Christian you are. Defend the little guy, and you're defending yourself.

Oh, and it's just the decent thing to do.

uBeam Withdraw Claims of Wirelessly Charging TVs?

It seems someone at uBeam might read my blog, and has updated a recent posting claiming that TVs can be charged wirelessly. Their page for a recent job ad read:

uBeam is an innovation that will breed innovation. Ubiquitous wireless power will lead to a world with smaller batteries and thinner, lighter devices. With wires virtually eliminated, TVs can sit in the middle of a room cord-free and light fixtures will become “stick-on” without the need for routed power. uBeam is also a universal standard, making those bulky travel adapters a thing of the past. Imagine charging your phone, laptop or even your hearing aid virtually anywhere, without any effort. This is life powered by uBeam.

uBeam have made these claims before, such as in a panel discussion, Oct 2016, the CEO explicitly states TVs can be charged wirelessly with ultrasound, and a previous incarnation of the company website that explicitly states flat screen TV charging. The current company website still carries images showing TVs and other high power devices, so while not stated, it does seem to be implied they can be powered - hence my question as to whether it's a claim the company still stands by.

In a blog post here, I laid out the case why I believed this was near impossible/impractical due to a wide range of considerations. Well, it seems they may have accepted my carefully laid out argument, and have now changed their claims in that page:

uBeam transmits power over the air to wirelessly charge electronic devices. the company seeks to enable a world where device charging is a seamless and untethered experience. It will be the Wi-Fi of energy.

While apparently it's too difficult to do a grammar check on three sentences, it's good to see that they appear to have accepted that my argument is correct, and that it is utterly impractical to charge TVs wirelessly with ultrasound. They even noticed that it's not a universal standard and removed that statement, given the explicit ultrasound limit in most of the world would at best result in about 3 mW at a phone, enough to charge in around 3 months of it being switched off. Oh, and that standards usually have to be run through Standards Association like the IEEE and take years of input from a large committee.

This is the latest in a list of reduced deliverable or performance claims from uBeam such as 'faster than a wire' down to 'trickle charge' style rates, charging through your pocket, mass production in 2016 that never materialized, and claims of efficient and powerful transducers in 2015 that the Chair of their Technical Advisory Board apparently never saw.

Are they withdrawing their claim of wirelessly charging TVs with ultrasound, or simply saving that surprise for later? No one has stepped up to challenge my assumptions or working, and I am still happy to discuss that with anyone who cares to. As you can see, "Arguing the Point" in the manner I suggested seems to work, though I'm getting the feeling it's working better when I blog than when I worked there.

You're welcome, uBeam!

EEV Blog takes on uBeam

Many readers of this blog will know the name EEVblog, it's a website and online forum for talking about  electronics run by Dave Jones, an Australian engineer. It's host to the uBeam FAQ, which puts together a lot of information on uBeam in one place. In addition to the forum, Dave makes videos where he delves into topics in a pretty entertaining manner, and for his 1000th video, he takes on uBeam.

Gotta say, he does a great job of covering the tech in an entertaining manner, not sure I could have done better myself.

An interesting point he makes is the difference between possible and practical, and it echoes a comment from one of my first posts a year ago that always seems to be missed:

"In theory, it can be done in limited cases, but in practice cost and efficiency issues will likely render it impractical." 

Enjoy the show.

Arguing The Point

Someone on the internet is wrong. You wish to let that person know they are mistaken, as well as inform others to be sure they too do not mistakenly believe this to be true. How do you argue your point in an effective manner, disagreeing with someone, while maintaining civility? There's a good post on How to Disagree by Paul Graham which lays this out, and I'd like to touch on this, especially as it relates to science and engineering discussions.

We're living in a world where we are surrounded by incredibly complicated technology - sometimes the simpler that tech looks on the surface, the more complex it is. There's a large percentage of the population that would have a hard time explaining technology as old as the internal combustion engine in your car, and things get worse from there as you move through things we all use every day but barely know it - encryption and compression get the latest episode of 'House of Cards' onto your TV, but care to lay out how that happens for me? 

More importantly, how do you tell when someone is making false or exaggerated claims about technology? The facetious answer is "study for long enough to become an expert" however even then it's hard - there's a lot of technology out there, and only so many hours in the day. If you don't know the technology, and people are arguing about it, how do you evaluate the arguments they make? One way is to evaluate how they are arguing, even if you don't understand fully what they are saying.

The pyramid in the graphic above is an attempt to lay out Paul Graham's hierarchy (I have no idea where it's from, I'm not taking credit for it, thanks to whoever did it). The pyramid you see here contains the 'best' arguments at the top, the 'worst' at the bottom, and as you can see, it's wider at the base to represent that it's a lot easier to make the worst arguments than the best - 80% of everything, after all, is crap.

At the base it's fairly obvious - if one side is saying "the other guy is a doo-doo head" then they don't have much on their side. Sadly, you don't have to go to far above this for most people to lose critical thinking and an ability to evaluate what's being said. Ad Hominem is actually quite effective in discrediting a party with some audiences - for example saying "they're just a disgruntled former employee with an axe to grind" while ignoring any detailed points that person may have made, or whether they are even justified in being disgruntled. The most common form of argument is often simple Contradiction with no evidence to support it - "My client is innocent, and we're confident that the jury will agree." Frustratingly, we seem to be in a world where there's a media bias to he-said/she-said and placing the weight of argument 50/50, regardless of actual merit of the case.

I've never seen this fake-balance more brilliantly demonstrated than by John Oliver in this Daily Show segment on the Large Hadron Collider, and how there is a "50/50" chance the world would end when it was switched in. The part in question is at around 3:00, but I'd encourage you to watch the whole thing, it's John Oliver comic genius.

Dr Ellis is my hero here. Watch him start at the 'top of the pyramid' and refuse to be dragged down into what we're used to from media. He stays on topic, doesn't get tricked by Oliver (way harder than you might think), sticks to his point, and doesn't let himself be drawn into the arguments from the base of the pyramid. It's a short segment but really highlights how awful the media are in pushing junk science from those with limited understanding compared to those with deep knowledge - but where's the audience in that?

To further illustrate that point, and to show an example of an argument on a technical matter, let's take with this recent statement from uBeam 

uBeam is an innovation that will breed innovation. Ubiquitous wireless power will lead to a world with smaller batteries and thinner, lighter devices. With wires virtually eliminated, TVs can sit in the middle of a room cord-free and light fixtures will become “stick-on” without the need for routed power. uBeam is also a universal standard, making those bulky travel adapters a thing of the past. Imagine charging your phone, laptop or even your hearing aid virtually anywhere, without any effort. This is life powered by uBeam.

I'll take that one bolded point - that TVs can be powered wirelessly with ultrasound in the middle of a room and try and 'refute the central point'.

I'll begin by trying an argument against it:

"They're a bunch of stupid poopy heads" - No, that's bad, that would be Name-Calling

"They're just disgruntled current employees desperate to share their misery with the prospective employee and have no idea of the basics of physics" - No, that's Ad Hominem

"Powering a TV with ultrasound in the middle of a room is not a practical possibility, and is around one hundred times larger a problem than charging a phone in the same manner. While it is theoretically possible, the costs, inefficiency, and safety concerns are staggeringly high, while practical alternatives are low cost, and there is no economic demand to make this happen. Regulatory limits make it difficult in the US, and impossible outside the US." - OK, now we're doing somewhere between Contradiction and Counter Argument.

Let's move this to an argument from the 'top of the pyramid' by Refuting the Central Point

I'll begin by stating my assumptions:

We're talking about a large screen TV, not a small hand held. The TV is in a room you have some control over the infrastructure. The TV does not have a battery and needs a constant supply of power to work that can't be interrupted. From Energy Use Calculator I'm going to take 100 Watts as the power requirement for a 50 inch LED TV. We'll be assuming this is in the USA, and that the pre-2015 OSHA safety regulations are in effect and that in no location is sound over 145 dB used. Outside the USA the 115 dB limit give a transmitter and receiver 1000x area increase requirement. Note this will also apply within the USA should current OSHA limits restrict usage to 115 dB.

I will assume a generous 33% efficiency on receive, with 50% efficiency from transmitter to receiver incorporating both distance and angle of incidence. I will assume there is infinite power available into the transmitter and that efficiency from the wall socket to the ultrasound conversion is also 50%.

I assume each phone case sized receiver, at 5 by 10cm, uses $10 in parts, and we need to sell at 3x BOM to make money.

I'll ignore nonlinearity for the sake of simplicity, even though that's likely to become an issue, and limit the separation of transmitter and receiver to no more than a meter.

Now my calculations:

100 Watts powered means 300 Watts acoustic needs to be received. (100 Watts at 33% efficiency). This compares to around 0.5 Watts requirement for a phone, hence the "hundred times larger" comment. At 145 dB ultrasound is around 300 Watts/m², meaning the receiver will need to be 1 m² in size, that is a square of 1 meter on each side, or equivalent. A 50 inch TV is around 25 by 44 inches in size, (64 by 112cm or 0.72 m²)  so as a meter is around 40 inches, that means the receiver will be around 1.5 times the size of the TV. Ooops, better get to work on that efficiency.

Now a panel that's 1m² is about the size of 200 phone cases, so around $2000 in parts, or $6000 in cost to sell and attach to that 50 inch TV, that costs around $500 right now.

The Transmitter needs to be twice the size of the receiver to take into account that 50% efficiency, so it's 2m², and from the above calculation that means $12,000 for the transmitter.

Note that if the regulatory limit is 115 dB then the area scales by a factor of 1000 and the transmitter and receiver are each larger than the room.

For power supply, going with the efficiencies, the wall socket needs to provide 100 Watts, times 3 for the receiver efficiency, times 2 for the transmit efficiency, times 2 for the conversion efficiency, for a total of 1200 Watts. Fortunately this is (just) what a 110 volt 15 amp circuit can provide at 80% max load regulations allow (1300 Watts).

At 5 hours usage per day, and 12 cents/kWh average power cost in the USA, that's 72 cents per day to run, or $262, of which $22 is the actual TV use, the rest the wireless power system.

The additional 1100 Watts to use the wireless power system will be lost as heat (it's about a one bar electric fire equivalent), so in the winter that will save money, in the summer you'll need AC. I'll call it a wash to simplify this.

Summarizing the Argument:

Given the above, to power a TV wirelessly with ultrasound, it will cost $18,000 in the transmitter and receiver, with an additional $240 per year in running costs. Assuming efficiencies are as high as stated. And that no-one walks into the beam, since any interruption will make the TV switch off. And that you don't mind a receiver that's larger than the TV. And a transmitter that's twice that size and isn't too far from the TV. And that the room gets a bit warm. And that it's in the USA and the OSHA limits don't change to match the rest of the world.

But other than all that, isn't that much more awesome than running a $5 cord to the nearest outlet or paying someone to run a cable under your floorboards?

I think I'm going to call this "impractical".

OK, sarcasm over - I've run my calculations, providing all assumptions, workings, references etc so that anyone who disagrees can say "Your assumptions are faulty, here's what they should be" and then it's simple job to rerun those calculations get the new numbers, and judge from there. If anyone who is an advocate of wireless power would like to argue with these, feel free to correct me, and let's see where it takes the numbers. Or argue that my methodology is incorrect, I'm happy to do so - but like every other time in this blog where I have presented numbers, equations, and physics as core to my argument, I expect I'll be met with silence or more questions as to my motives. The top of the pyramid meeting with a response from the bottom.

My point to most people is this - if you don't understand the physics or details of a technical discussion like this, look to those presenting actual data, references, and their methodology and assumptions. If there is one side doing that, and the other calling names and questioning character, then you should likely consider one side's argument as superior to the other. If both are arguing methodology and data, then you may be watching a genuine scientific debate, which is good and healthy, it's what we want. If both are calling names, they're both idiots.

What Does It Take To Switch a "Phone Charging" Light On? Pt II

Following uBeam's demo, EEV Blog contributor Howard Long made a very interesting video showing how you can turn on a phone charge light with ultrasound. It's about 4 minutes long, with audio commentary, and gives more info in that 4 minutes than in the entirety of uBeam's demo. If this subject interests you at all, I encourage you to watch this.

From his comments (edited for brevity, read the whole thing here):

I could get it to light visibly with about 1mA at a distance of 2cm ... At 2cm distance, I had about 2mW, giving it a 2% efficiency. However, ... perhaps only 15-20% of the transmitted power appears at the rx anyway. So beam forming and reasoanably sized apertures on the receiver are essential facets for this to work.

... That camera thing is an Nvidia Jetson which looks like it's for visual device tracking. ... If it needs visual indication of where the target device is, and the sensors are on the rear of the phone, the phone will have to be used face down for a ceiling arrangement, and you won't be able to hold it in a normal fashion to make a call or use the screen. Even wall mounted, assuming nothing's in the way, you'll have to figure out new ways to hold your phone.

In its current form and key use, as a phone charger, this remains practically speaking a non-starter.

It seems an engineer reproduced a basic version of the uBeam demo in a day with about $20 in parts.

The phone charge indicator lights at 1mA, which implies 5mW (5 Volts supply) and so would take about 1000 hours (~6 weeks) to charge the phone - if it weren't for the pesky fact that a phone requires around 500mW to operate, on average, so it would make no appreciable charge effect at all. 

Now of course there's only a single element here, not a full array which could emit more power, but the key point is that a charging symbol tells you nothing about whether it is practically charging. You need voltage and current to know the actual power, and you need it at both transmitter and receiver to get efficiency (which he's calculating as 2% in this setup, pretty good actually for through air). Those are key numbers you need to have. From Howard's numbers 100 transmitters will get you that 500mW and maintain charge at a constant level, in an ideal world setup - possible but very large and introduce many questions on practicality and cost.

I like the way Howard also brings out a key point in this video - of course you can send power through the air by ultrasound. That's never been doubted or questioned, here or on the EEV Blog. What is questioned is how much power can be received, the efficiency of that, the safety aspect, the cost of transmitter and receiver, and the practicality for the user.

None of those points were addressed by uBeam, other than the emphasis on slow "trickle charging", implying the "faster than a wire" claims of 2015 aren't going to be happening.

Anyway, bravo to Howard Long for showing how to put together a short, clear, technically accurate demo from which you can actually learn something.

What Does It Take To Switch a "Phone Charging" Light On?

A few follow up points on the post from yesterday on the uBeam wireless charging.

I did like seeing this quote from the journalist:

Asked why the battery percentage didn’t appear to increase rapidly, Perry shakes her head.

“You’re thinking about it the wrong way, this is about a paradigm shift,” she says. “If you’re moving from your car to a coffee shop to work and your phone is charging while you’re using it, it’s no long about what percentage you’re at. You could stay at 1% all day.”

So it's an artful dodge of the question (that the journalist didn't press on), and perhaps an admission that the charge rate is not 'faster than a wire' as has been stated before by uBeam. It's more the "trickle charge" route, where you get tiny amounts of power over a long period of time. That "faster than a wire" claim was made at a time when the company was stating 1.5 Watts minimum charging which is much more than "trickle charge", and would fully fill your phone in 3 to 4 hours. Saying you stay at the same charge rate all day implies you are charging at an overall average of around 0.5 Watts, including all the times you are not around any uBeam transmitters, but if the charge rate is much greater than 0.5 Watts, why not say?

I noticed in that article the transmitter and receiver 'prototypes' back then in November 2015 were much smaller as well.

If there is actually a "trickle charge" regime, then the phones need charged as they are in use, and most use is a person standing or sitting holding the phone, fingers around the back, at around 45 degrees. Given line of sight, and assuming the 'bezel free front' of most modern phones, this implies the transmitters will need to be on the floor or base of the wall to get access, but will also likely be cluttered. Fingers on the phone case will prevent charging - unless of course you want to hold your phone by the edges as you use it (unlike in the picture above). I'm not seeing how trickle charge works with a mobile user, you need rapid charge in such circumstances. The practicality here, I'm not seeing. Maybe uBeam can layout the actual use-case scenarios they envision?

Also interesting was the quote from technical adviser Matt O'Donnell:

“When Meredith called me in 2015, I was curious and skeptical as hell, because you just hadn’t seen efficient airborne transducers,” says O’Donnell, dean emeritus at the University of Washington’s college of engineering, who now serves as uBeam’s chief technology advisor. “But holy moly, the leaps they’ve made in the past 18 months have been impressive.”

Hmmm, so all this advancement was made in the last 18 months, they had much, much less back then. But I'm confused because in September 2015 uBeam made this statement (among others):

“We’re at a massive inflection point,” said 26-year old uBeam co-founder and Chief Executive Meredith Perry. “We are about to head into a completely new phase of growth.”...In order to ease the transition into production, uBeam said today it has hired former Cisco Vice President of Supply Chain Management Jeff Devine as chief operating officer...“When we were seeking out an operations candidate we were looking at someone with decades of experience from taking a product from prototype to production,” said Perry. “He’s going to be the one that’s going to help us take this from our small shop to what will become our massive multi-million (unit) production next year.”

So which of those is true? Production ready in September 2015, or not? As with the "faster than a wire" claims from 2015 there are some implications as to 'perception vs reality' over the last few years if what Prof O'Donnell says is accurate. (COO Devine left his role at uBeam earlier this year before 'inflection' happened). For a further point of reference, I left the company at roughly the time these claims were being made.

The current receiver case is pretty interesting too. Looking at it, I'd guess 6 by 11 by 1.5cm which is larger than the phone itself, for around 100 cm^3 of volume. A standard battery for a Galaxy S5 is about 15cm^3 so you could have around 7 of those packed into that volume, giving you around 4 days of continuous use before recharging, and would cost about $70. If uBeam are using Murata (or Murata style) transducers in that case, there's around 60 of them at $3 each, so $180 just in transducers there. I'm not seeing the practicality or economics here.

(For those wondering - Murata are the primary maker of the parking sensors that are used in many cars, using ultrasound as the detection method. They're the small circles you see on bumpers, and individually look like cylinders about 1 cm each in diameter and height. They sell millions of them every years to the auto industry, and are around $3 each in bulk. You can go buy them yourself if you like.)

I did notice they have two different arrays that are used at different times, and I wonder if they are operating in the same manner, or if they are specced to handle different test conditions, and what is seen in these demos can't all be done on the one demo system. It's a little hard to tell from the videos as shown.

Now I could make a few more comments, especially on the posters in the background of the video and what they give away, but that's just going way too detailed even for my blog. 

Last point for now - the above picture shows a Kindle Fire on the right, and if you look in the bottom it's indicating "charging", but what rate is it charging at? 4.62 volts and 10 mAmps - basically  under 50 mW. To give you an idea of what that amount is, a typical phone batter is in the 5 to 6 Wh range, which means at this rate it would take over 100 hours to charge your phone at that rate. That's also assuming the phone is switched off, as it's typically consuming at around 500 mW so without that level of 'charging' it's consuming power faster than it's receiving it. I'm not seeing the practicality if that's the case. (A demo of a charging indicator coming on can be found in a newer post, here)

All this indicates is that the floor to show a device charge light come on is not the same as actually charging it - you need to see something like the screen on the left with voltage and current to know actual charging rate. This floor varies by device (iPhone seems to trigger at a higher floor than Android, and the floor varies with charge level IIRC), it's possible it's charging much faster (faster than a wire even?), but if it is, why not say?

As has been said before - physics doesn't prevent you sending power via ultrasound, or RF like Energous does, but can you send enough power to be useful, safely, efficiently, simply, and cost effectively?

Someone was paying attention

Almost immediately after my article yesterday, it looks like someone at uBeam was paying attention and actually did a proper, adult, professional PR piece and got the company onto the front page of USA Today. Much less embarrassing! :) It does also show part of my article was wrong - at least some people care!

To very quickly give a summary:

Reporters buy a phone at a local outlet to use charging (shows phone isn't tampered with, well done), put it in the brick case, and get the charge light to come on. Shows a device with an IR camera for tracking. Done with more than one phone at around 4 feet. They go on to say:

The technology is at least a year away from commercialization, and it faces significant hurdles from ever getting out the door of this 30-person start-up. Even though it can at present power a handful of phones, it's not clear what leaps need to be made to charge a busy coffee shop. And consumer questions will linger about safety as well as cost.

So at least they maintain some skepticism.

In the short time I have available this morning, and I'll update later tonight, I'll make the following comments:

In all this time, have reporters still not learned to press on the key questions? "How much power is being received?", "How much is being sent?", "What's the efficiency?", "How much does it cost?", "Have you proved it safe?", and "If this is what you have now, what were all those 'prototypes' you were talking about 2 years ago?". But those are actual questions that matter, and basically we know the same today as we did yesterday (which indicates it was an awesome PR piece, lots of coverage with no actual info).

Technically, it's still hard to say exactly what's being done, and there's not much to add beyond my earlier articles. The video does make it look like off-the-shelf Murata devices are being used and focused into a tight beam straightforward. Efficiency and safety questions are dodged.

Is this enough to convince someone to put more money in? Most likely, so let's see if someone big enough to price a round steps up or if it's smaller less sophisticated investors again.