The LED Lighting Revolution

In this week's myth Kat Arney takes a look at the science of the midnight feast, but not in the way you might think…

Kat - The land of nod is a mysterious place, and we are blissfully unaware of most things that are happening to us while we sleep. It’s common knowledge that one of the things we do is eat spiders - a remarkably precise eight every year. So where did this idea come from?

Topically, given the current media discussions about fake news, it was made up by a journalist back in 1993. According to the myth-busting website Snopes, Lisa Holst wrote an article for the magazine PC Professional, highlighting the way that emails packed with ridiculous made-up facts were being circulated by the gullible and credulous - how times have changed, eh? As part of her piece, Holst presented her own list of totally made up stats, including the one about eating eight spiders. In turn, she got it from a list of common misconceptions about insects in a book published back in 1954. However - and this must be pointed out with some irony - there’s no independent confirmation that Snopes’ story is true either.

So let’s think about the likelihood of snapping up a spider in your sleep at night. According to Scientific American, which spoke to several spider experts in search of an answer, spiders are more likely to run away from a sleeping human than start exploring us. They’re scared off by vibrations, produced by our heartbeats, breathing and especially snoring, and people are likely to be woken up by the sensation of something crawling on their face before the spider gets into their mouth. However, there are plenty of anecdotal stories of people being bitten by spiders in the night, and also biting back, reporting finding bits of legs between their teeth in the morning. So although we probably do eat the odd spider during a lifetime, it’s impossible to know for sure, or how many. The only way to find out would be the film many people asleep, night after night, then carefully watch the tapes to spot any spiders crawling their way into an open mouth. Not only does that sound like a very boring research project, it’s also more than a bit creepy in itself.

If you’re worried about eating spiders or other insects, you’re far more likely to have chomped on them when you’re wide awake, as they’re often found in processed food and one estimate suggests the average person unintentionally eats about half a kilo of insects every year. There are even legal limits on the amount - for example, the US puts a limit of 60 insect fragments per 100 grams of chocolate, in case you’re wondering why your fruit and nut bar is extra crunchy. Finally, rather than worrying about accidentally knocking back a few spiders at night-time, some cultures even make a point of eating arachnids. Fried spiders are a popular street food in the Cambodian town of Skuon, where a species of tarantula the size of your palm is mixed with sugar, salt and garlic and then fried in oil. Apparently, they are crispy on the outside and soft in the middle, tasting a bit like a cross between chicken and fish. Proof - if ever it was needed - that anything can be made edible if you fry it with enough garlic. And while I may never know exactly how many spiders I’ve eaten by accident, I think I’ll give these ones a miss.

A new study suggests that thousands of middle-aged women could be suffering silently from bulimia, anorexia or binge-eating. These types of mental illness are usually associated with teenage girls. However, the research from University College London has shown 1 in 28 have women in their 40s and 50s are struggling with an eating disorder and the majority of them are not seeking any help or treatment. Liz Fraser had bulimia for 15 years and as she explained to Graihagh Jackson, it nearly cost her her life...

Liz - With mental health problems, I think it’s very difficult to identify the moment that it started. I was a fairly typical case I guess. I was 15, not very happy at home, brother leaves home, a lot of academic pressure, very highly driven, very high standards. But losing a bit of weight became a thing and you had a graph. I used to like plotting the numbers and, if the numbers didn’t go down, then that was a bad day. So everything good or bad became associated with this graph, regardless of my size, that was almost immaterial. What starts as something every so often, then becomes all the time, and then become an addiction. And at that point, even if you don’t want to exhibit these behaviours, even if you don’t want to behave that way you still will, because that’s what you do.

Graihagh - Was there a point for you where you just thought this is it, I’ve gone too far and I need help or, what was that turning point for you?

Liz - For me, as with many people, there were probably many points like that. That’s one the frustrating things with addiction, isn’t it? You have those moments where you go right, I’m going to sort this out, I’m going to put lists on fridges and I’m going to… and then you don’t. You do for a while and then you have a relapse and every time that happens you think 'damn it, I was not going to do this.' I was going to be determined and then that knocks you even further down. Then, for whatever reason, you wake up feeling stronger and you go right, I’m going to sort this out. So I think you have to be prepared, one has to be prepared in the recovery process for these relapses to occur and not to get lower and lower down.

I had three children during this time - not when I was 15 I hasten to add. This continued until I was 30 - 30’s often quite a turning point for people. So I looked well, and I appeared to be functioning well, and I got a degree from Cambridge and I was making films and TV programmes. I had young kids, I was looking after them but to anybody in the outside world, I was very well. But I think the real crunch came for me when my youngest was about one or one and a half and just one day in my kitchen I nearly died standing right there. I can remember feeling this ice cold, freezing, that was it.

Graihagh - Sadly Liz isn’t alone. Dr Richard Slye from the Eating Disorder Charity BEAT…

Richard - They affect about 725 thousand men and women of all ages and backgrounds in the UK. It’s not just this stereotype that people have of young middle-class teenage girls going through a phase or doing it to look good. These are serious mental illnesses which can impact on anybody.

Graihagh - Now Liz described her experience of bulimia. She had bulimia for 15 years but, amazingly, she was functional still, she had three children. But my understanding is that eating disorders actually claim more lives than any other mental illness like depression or psychosis.

Richard - Yeah, absolutely. Anorexia nervosa has the highest mortality rate out of any mental illness out there. These are illnesses that can really destroy someone’s life and impact greatly on the family of that person as well.

Graihagh - Because this study published recently in the BMC is looking for the first time, which I find very staggering, about the prevalence of eating disorders in women across all ages, particularly in their 40s and 50s, and I was surprised at some of the statistics in that. It was 15 percent of women had had an eating disorder at some point in their life and 3.6 percent were currently struggling with one now. Is this something that you were surprised by?

Richard - Well first I’d like to say we wholeheartedly welcome this research. There’s not enough research into this and this is actually really important and exciting research. This figure of 15 percent of women having an eating disorder at some point in their life and 3 percent currently suffering is actually quite alarming but it’s not something we’re particularly surprised by.

Beat run a helpline which is open 365 days a year and last year, 15 percent of our calls to the helpline were about someone over the age of 40. This research further supports the importance of providing an appropriate treatment pathway for individuals with eating disorders all ages. Because, at the moment, the focus is very much on helping young people out, and people in their later years or who are in midlife find it very hard to get the treatment they need for their eating disorder.

Graihagh - What is the treatment for it? How do you get better or recover from something like this?

Richard - Recovery is hard but it’s possible and it’s incredibly worth it. Generally, it’s going to be a form of talking therapy and people can start thinking about the reasons behind their behaviours.

Graihagh - Because the sad fact is, and this is something the paper highlights, is that those who reported having an eating disorder, less than a third of them actually sought any help. I just wonder why is that, what is the barrier there for people getting what they really deserve and need?

Richard - I think in this population that we’re talking about, they can find it almost embarrassing to go to a GP and say that you have this illness which is wrongly associated to be a teenage girl’s illness, and I think there can be a lot of shame or embarrassment around that.

Graihagh - Liz, despite all the stigmatising and stereotyping, did seek help and turned her experience into something positive - a website.

Liz - It’s inmyheadcase.com.

Graihagh - She hopes headcase will turn mental health on its head by sharing her experiences…

Liz - Headcase came out of all of my experiences of different types of mental health problems, whether it be eating disorders when I was younger. When I was in my 30s I had panic attacks and then I had a breakdown in my early 40s and what I found, every time I talked about it that person would say “I had that too” or “my mum had that,” “my friend had it,” “there’s a guy at work who has that.” It really began to strike me that this stuff is everywhere! Mental health issues affect absolutely everybody, and if it’s not you, it’s someone you know.

It’s part of your life and for as long as we keep it as something weird, it will be associated like that. I want people to wear the Headcase badges and stand up and say, “yeah, I look after my head. I’ve got literally no problem with that at all.” If I’ve got a sore knee I get it seen to.

If I’m feeling anxious, jumpy, panicky, freaked out in any way, I will go and find some help about that. I acknowledge that and I’ll look after my head just as well as I look after my body.

How and why are they so much more efficient than a standard light bulb? Tom O'Hanlon went to find out at the Cambridge Centre for Gallium Nitride with Rachel Oliver...

Rachel - Welcome to the lab. First things first we need to put the lab coats on…

Tom - Just do up the poppers...

Rachel - Now I’m sure lots of people have seen an LED bulb but what they actually look like these days? It’s very much like a normal light bulb, maybe with a sort of frosted glass cover. And it’s a bit difficult to tell why this is different to a normal light bulb that you might have been buying for years and years. So what we thought we might do this morning is take one apart and find out what’s inside. Now we’re going to do that using a diamond saw over here…

We’ve got here an LED bulb that’s really in several parts. We’ve got this yellow globe - it looks a bit like a small ping pong ball and then underneath we can see a load of circuit boards and things like that.

Tom - Okay. So the LEDs are those little chips, maybe about 5 mm across?

Rachel - Yes, something like that. This bulbs got 6 LEDs in. Different bulbs have different numbers. They’re quite small chips; they’re actually quite small devices, and they’re made from a material called gallium nitride. That’s a material that you don’t find in nature. LED manufacturers grow it in big crystal growth systems and we actually have one of those big crystal growth systems here where we make experimental LED structures and try and improve them.

Now we’re in the growth lab and what we’re looking at here is one of our crystal growth systems. It’s about the size of a transit van but a lot of the bulk is actually just things like control electronics and systems that handle gases; they move gases around.

Tom - The gallium nitride is built up by reacting a gas called trimethyl gallium, which supplies the gallium, with ammonia, which supplies the nitrogen. These gases are passed through a surprisingly familiar piece of plumbing…

Rachel - The gallium and the nitrogen come through a structure called a shower head, which looks like a shower head.

Tom - Like the nice ones you get in fancy hotels?

Rachel - Yes, exactly. Admittedly, it doesn’t look much like my shower head at home which is white and plastic.

Tom - Below the shower head is a wafer similar to what you get with ice cream. But instead of biscuit, it’s made from either of man-made sapphire or silicon. Rachel heats these wafers up to a thousand degrees Celsius and the gases split apart on the wafer surface and react to build up the LED crystal layer by layer.

Rachel - The gallium nitride layers that are the base that we grow for the LED, they’re typically about microns thick, so a micron is 1/1,000th of a millimetre. The actual light emitting layers (the bit the light comes out from) are much, much thinner somewhere in the order of a millionth of a millimetre. It’s very, very thin light emitting layers.

Tom - We’ve spoken about how you make the material used to make these LEDs, but how do they actually emit light?

Rachel - Well, I’ve got something in my office which might help you to understand that so why don’t we walk back through there…

Tom - To my surprise, Rachel showed my a wooden game I hadn’t seen in years - it’s called Labyrinth. Do you remember it?

You have to roll a ball bearing through a maze, twizzling knobs on the side to tilt the board up, down, left, and right trying to avoid it falling down some holes. How is this anything like an LED, though?

Well, it comes down to these layers. On one side of the LED, the layer is tweaked so there are extra electrons which are negative. On the other side, some electrons are missing leaving behind holes which are positively charged. When you flick the light switch on, the negative electrons and the positive holes are pushed towards each other.

Rachel - So, we can think of our electron as being the ball bearing and the holes in the toy are just the holes in the crystal and where the electron and the hole meet, the electron basically falls down into the hole just as the ball bearing falls into the holes in the toy.

Tom - So how are your skills at this Labyrinth game Rachel?

Rachel - Not great. Shall we see how far I can keep it going before my electron recombines with my hole. Let’s have a go… I’ve got to get round my first corner now and I’m not sure I’m going to make it. Uh, I’ve managed one corner. You heard there the process by which my ball bearing, which is my electron, lost some of its energy. It fell down and it went clunk at the bottom and some of the energy it had, when it was at the higher level, got converted into sound energy. In the LED, obviously, the electron and hole meeting gives us light, but the basic principle is just the same.

Tom - In these LEDs, the electron falling into the hole creates blue light. To get white light you need what Rachel described earlier as a yellow ping pong ball. It’s coated with chemicals called phosphors which convert some of the blue light to yellow. Yellow light, plus blue, makes white.

Rachel also told me about another trick LEDs use to make the light more efficiently…

Rachel - It’s all to do with these very, very thin layers I talked about which actually give the light out. The reason they’re very, very thin is that we’re using them to trap the electron and hole together in the same place. Now it’s like if you and I needed to meet up to have a cup of coffee, if I said to you “great, let’s meet up tomorrow and we’ll meet in Cambridge,” well we might find each other but it’s not very likely. If I say to you “let’s meet up and have a coffee in the common room at the Department of Material Science,” it’s quite likely we’ll actually manage to find each other and have our coffee and our chat. So we’re doing the same thing with the electron and the hole and because they meet quickly and efficiently and combine to give out light, there’s no time for them to wander off and find maybe mistakes in the crystal where that process by which they combine could go wrong and give out heat.

Really, in terms of the research we do, one of the key things we do is think about the structures that give out the light. They’re very, very small and we try and engineer them so that that process where the electron and the hole meet is as fast and efficient as possible, and that makes the overall device as efficient as possible.

If we switch to laser lighting, it could transform our homes and even yield glow in the dark curtains. Chris Smith caught up with Steve DenBaars to find out more...

Steve - You could imagine you could have one blue light source per house and, rather than run your light around with copper wires, you could route the light with plastic or glass fibre optics through the rest of the house and then convert it to white light whenever you need it. And, therefore, you could drop a lot of the cabling needed for lighting but you could also imagine a very different looking lighting fixtures. You don’t need big bulky metal fixtures anymore, you would need very small sources or you could even think about weaving fabric into the curtains or the ceiling to get a distributed effect.

Chris - So we’re talking about the death of Edison's dream really aren’t we? We’re saying this is the end of the light bulb as we know it - we don’t need that technology anymore. We just need to build fixtures and fittings that could take a fibre optic input, driven by a laser which could be hundreds of feet away elsewhere in the building and the light arrives in a tube called a fibre optic, goes into that surface, and the whole wall or the whole ceiling or, even as you say, your curtains glow and that illuminates the room.

Steve - Yeah, that’s right. We think this gives the designer a lot of freedom. But I will point out you can actually see laser lighting today already in Europe. It turns out that BMW and Audi have already released a high-end automobiles with laser headlights because it’s so bright and efficient at directed light as well. I think there’s more than a thousand cars already on the roads in Europe using this laser lighting technology.

Chris - Why do you think that running fibre optics round your house and bringing the light in as light rather than electricity in a copper wire is better?

Steve - Yeah, that’s a good point. The fibre optic cable could be extremely small - we’re talking here less than a millimetre. So you don’t need to waste a lot of copper material which, as you know, is expensive but also you could potentially get an electrical shock. So it just lets you make lighting fixtures that are much smaller. In existing buildings, they allocate almost a foot for all this cabling and fixturing. I mainly think is a way to just not only design cool fixtures but save on the cabling, materials cost, and metals associated with that as well.

Chris - With an eye on the whole concept of the internet of things, we talked in a recent edition of the Naked Scientists about the concept of li-fi (your connection to the internet being by visual signals from light bulbs), could you use this as an extension of that? Could people connect to the internet, download data by their wall flashing imperceptibly at them?

Steve - Well, I’m impressed, because you already made the connection that we’ve been working on research only for two years in a hard way that is. I think there’s been some work in the UK. I think Professor Harold Hoss has been doing li-fi with LEDs, but we can do the same thing with laser lighting. In fact, we’ve already done that and we’ve demonstrated communication speeds more than 100 times faster than you can do with the traditional LED li-fi bulbs you have in the store, that is. We are able to transmit 5gb per second. So just to give you some sense, that is getting up into the same speed you’d use in a fibre optic cable.

Chris - Is this safe, Steve? If I’ve got fibre optics running around my property and they’re full of extremely intense coherent blue laser light, if I were to accidentally chop that into that, now I wouldn’t get an electric shock, but I could blind myself couldn’t I?

Steve - Yes, so we really need to develop failsafe optical systems and sensors. On a very high level, I’ll just tell you some of the safety schemes we are working on is that if the cable is cut, within nanoseconds the cable is able to sense that it’s actually been cut and it immediately shuts off the laser.

Chris - How long is it going to be, do you think, before it’s de rigueur to walk into your lounge and you will flick on a switch which won’t activate a light bulb in a ceiling, it will make the ceiling glow and the curtains illuminate?

Steve - It’s going to take a decade, I think, to really make laser lighting commonplace. However, it’s already showing up in automotive lighting and even in cinema displays in Asia.

Chris - Well, that’s interesting isn’t it? So, if your internet connection comes through your sofa, does that make you a couch surfer I wonder? 

That was Steve DenBaars from the University of California, Santa Barbara, thank you very much and thank you to him.

Also with us this week is Colin Humphreys. Do you fancy the idea of curtains illuminating your room from a laser source colin - what do you think?

Colin - You could have a whole wall of illumination in the room which might be interesting and we can, in fact, use an LED to do this as well. So a laser may be slightly more powerful but the LEDS you can use. In fact, in museums, they’re using this to illuminate cabinets so you don’t the fibres coming and they’re LEDs on the end.

Chris - Graihagh, do you like the idea of a sofa that illuminates the room?

Graihagh - I just can’t really imagine it. That or a glow in the dark curtain. I don’t really see the attraction in that rather than just having a regular light. What is the attraction?

Chris - I think the point is we design rooms at the moment with light sources being in the ceiling in a central point. You get dark shadowy corners and it’s dictating how room are formatted and if you actually had a light coming from all different kinds of places, it would allow designers a lot more freedom.

Graihagh - I suppose it might seem quite more natural as well.

Chris - It could do because it would mean that the room didn’t have dark corners anymore.