Interviewer: Lucy Vernall (Project Director, Ideas Lab)
Guest: Dr Emma Carter
Intro VO: Welcome to the Ideas Lab Predictor Podcast from the University of Birmingham. In each edition we hear from an expert in a different field, who gives us insider information on key trends, upcoming events, and what they think the near future holds.
Lucy: Today we're with Dr Emma Carter, who is Research Fellow in Micro-Engineering. Welcome Emma. So what's micro-engineering?
Emma: Micro-Engineering is basically the design and fabrication of any devices that are smaller than a millimetre.
Lucy: Smaller than a millimetre? That is tiny! How do you make things that are smaller than a millimetre?
Emma: Well, it uses completely different fabrication processes to traditional engineering manufacture. Essentially, they rely on photolithography, where you would put a mask of your design over a silicon wafer and this would be coated with a photoresist polymer. And then you would expose the design to UV light and then develop it, and you'd be left with the design that you have on the wafer. And then you would get rid of the material you don't want, using deep reactive iron etching, where you basically bombard it with ions.
Lucy: And you're left with something very, very small?
Emma: And you're left with some very small details; very small components. And if you start off with a wafer that has different layers, for example, a thick silicon layer, then a silicon dioxide layer, and then another silicon layer...when you etch away the top silicon layer then you can also etch underneath the silicon dioxide using hydrophloric acid. And then you release some of the parts so you actually have moving parts.
Lucy: So when you've made your thing that's very, very tiny, what kind of things can you make?
Emma: You can make accelerometers, gyroscopes, pressure sensors...basically things that move and vibrate, and so can be controlled using electricity. Or the other way round, you can move them and detect how much they've moved.
Lucy: So these tiny sensors and gyroscopes, what do they go into?
Emma: You'll find a lot of them in your car. For example, to detect when you've just had a crash - to set off the airbags and the seatbelt pretensioners. Also some cars have pop-up bonnets. So they'll detect that you may have hit a pedestrian and then the bonnet will pop up to provide a cushioning effect for the pedestrian. Electronic stability control also relies on these accelerometers. There are tyre pressure sensors as well to warn you when your tyres have low pressure. You'll also find a lot of them in consumer electronics, such as smartphones and [Nintendo] Wii remotes.
Lucy: So if you've got a smartphone that's one of those ones that when you move your phone the screen changes, then it's got something like a gyroscope in it?
Emma: Yes, exactly. It would be able to detect how much you've moved it and when you've moved your phone.
Lucy: Anywhere else in the home or workplace we might find these?
Emma: You'll find MEMS devices in your printers. The inkjet nozzles are micro-devices. And...
Lucy: And MEMS devices are?
Emma: Microelectromechanical systems.
Lucy: OK. So really they're all over the place.
Emma: Yes. They're everywhere.
Lucy: And they're growing? Or the numbers of them are.
Emma: Yes they are. It is a rapidly increasing industry. The market was worth about $6bn in 2009, and it's been predicted to be about over $9bn by 2015. So it's a growing market.
Lucy: And I understand that it's not just these kind of gadgets and gizmos - cars and phones and printers - but actually there's quite a lot of medical applications for these as well.
Emma: Yes there are. This is a growing area really. One of the things that's used at the moment is monitoring the activity of the person wearing a pacemaker and adjusting the pacemaker accordingly. There's something that's being developed at the moment, which is E-Nose technology.
Lucy: E-Nose? Is that electronic noses?
Emma: Electronic nose, yes.
Lucy: And they use these micro devices?
Emma: Yes. There are larger electronic noses, but they're developing microelectronic noses. These can be used in food monitoring. So detecting if food is going off in transportation.
Lucy: So the benefit of having it very small is…what? It can be put in packaging? Is that the idea?
Emma: Yes, exactly. Yeah. The smaller they are the cheaper they are, and the more of them you can have.
Emma: So you can have them everywhere. And also illness diagnosis. You can use them to detect harmful bacteria. Even people researching lung cancer indicators in patients' breath using an electronic nose.
Lucy: So in the future you might have, like, a breathalyser type test, which might tell you if you've got particular illnesses?
Emma: Yes, exactly. So the way an E-Nose works is: the device would have an array of resonators, with each resonator having a different coating that reacts to a different volatile organic compound. And when it reacts - so when this compound is absorbed onto the surface - it changes the mass of the resonator and that then changes the resonant frequency of that resonator which can be detected.
Lucy: So you can tell what's been breathed onto?
Emma: Yes. So you can, ideally, identify the gases involved.
Lucy: Wow. So presumably things like E-Noses are powered by batteries? Is that how it works?
Emma: As we move into new applications for MEMS, particularly if you want to place sensors inside the body or place them remotely, then we need to think of new ways of powering them. And one of the ways that's being investigated a lot at the moment is energy scavenging. So this is using energy that's freely available, such as solar power, vibration, heat, wind, even blood pressure. Different ways of using energy that's available and converting it to electricity to power these devices.
Lucy: So if you've got a device implanted inside your body, your own blood pressure can act like it's a battery? That'll be enough power to keep it going?
Yes, that's the idea. Yeah. So it's for low-power applications, this kind of energy scavenging. Another things that's being developed is knee-strap energy harvesting. And these, apparently, can yield about 2.5 watts per knee, which would be enough to power five mobile phones.
Lucy: Five mobile phones per knee?
Emma: Per knee.
Lucy: There you go, so we all know what we could power now if we just had knee-straps!
Lucy: So looking ahead into the future. We can already do amazing things with these micro-machines...[so] what's next?
Emma: Well, one of the really interesting things that's being developed at the moment is an artificial skin for people with artificial limbs so that they can have the same sense of touch as a person with a real hand could have. So this would involve arrays of pressure sensors and humidity sensors to give them a real sense of touch.
Lucy: So if you've got an artificial hand you'd actually be able to feel a bit of pressure or a bit of heat or something?
Emma: Yes, exactly. So rather than just having one pressure sensor per finger - so you could detect that you were touching something - it would be more sophisticated than that. So it would be a whole array of different sensors - so pressure sensors and temperature sensors - to give you that qualitative sense of touch.
Lucy: Which is obviously where the "micro" comes in, because you can have lots and lots of them if they're very, very tiny.
Emma: Exactly, yes.
Lucy: Like real skin.
Emma: Another application for these kinds of tactile sensors would be in the area of remote surgery. So, robotic surgery. This is where the surgeon would be remote from the patient - either in another room or in another country even - and would be controlling the surgical tools that go into the patient. And improved sensors on the tools would really improve the performance of the surgeon because they'd be able to feel exactly what they were touching and how close they were to certain tissues.
Lucy: So at the moment there is robotic surgery already, but as a surgeon they don't get that feedback mechanism of actually being able to feel what's going on very well?
Emma: Exactly, yeah. They don't have very good haptic feedback. It could be a lot better.
Lucy: So for you personally, what are you doing at the moment?
Emma: At the moment I'm working on a microelectronic nose that uses a slightly different method, in that usually you would have one resonator and one sensor per smell that you're trying to detect - per gas - and then you have one input and one output per resonator. And what we're looking at doing is designing an array of coupled resonators so they're all linked together. And you just have one input and one output for this whole array of resonators. So, say for example if you have five, then you would have one different coating on each resonator. And so that reduces the number of wires that you have so it would reduce the complexity of the device and reduce the cost of the device.
Lucy: And is that a general E-Nose? Or is it a specific E-Nose for a particular thing?
Emma: Well what we're developing is the general design for this coupled mass resonator array. To make it specific to an application you would functionalise each of the resonators. So have a different coating on each of the resonators that would react to a specific gas.
Lucy: So this is a general one?
Lucy: And might it be that we have E-Noses on our phones in the future?
Emma: Quite possibly. Yeah, I think you could use them for lots of different applications. They could warn you were entering an area that had some dangerous chemicals in it, for example. They could be used for explosive detection...
Lucy: All the things you never knew that you needed on your phone - now you need them! Dr Emma Carter, thanks very much.
Emma: My pleasure.
Outro VO: This podcast and others in the series are available on the Ideas Lab website: www.ideaslabuk.com. On the website, you can find out how to e-mail us with comments, questions or suggestions for future topics for the podcast. There's also information on the free support Ideas Lab has to offer to TV and radio producers, new media producers and journalists. The interviewer for the Ideas Lab Predictor Podcast was Lucy Vernall, and the producer was Andy Tootell.