IEEE Sensors – Day 2

30 10 2011

Another packed day here in Limerick. The plenary looked at the developments in sensing technology applied to the mobile phone market and how this will enable ‘The Internet of Everything’. Current research in this field include the use of ultrasonic transducers to communicate with your smart phone (they can hear it even if we can’t), chemical sensors in smart phones for first responders and MEMs based particulate monitors. However, despite the increase in processing power now common in phones (1GHz processors are in our pockets now – that’ the equivalent of 25 Pentium PCs) it’s still the LCD display which drains the battery. There’s a good summary relating to the application of energy harvesting to this problem, which is Vullers, et al, Solid State Electronics, Vol 53 (2008) pp684.

From there, it was off to listen to the application of emergent behaviour to groups of sensors. This showed that it is possible to realise the optimisation of a group of sensors by enabling them to sense their local environment and communicate only with their immediate neighbour. Whilst the application described the minimisation of noise levels in aircraft engines, this has the potential to offer a complete paradigm shift in how we make decisions from a large sensor installation. The next talk, focussed on the development of MEMs based logic structures for hostile environments, mostly targeting ionising radiation and high temperatures. Based on tungsten contacts, this does ask the question about neutron activation, especially as it becomes a gamma emitter with a 24 hour half life! The results though were very encouraging, demonstrating 2V activation and a 100MHz limit, with a 1uW leakage power and a lifetime of 10^9 operations.

A talk on SiC based detectors showed a significant piece of work on understanding H2S detection, through the use of Density Functional Theory (DFT) simulations. This showed that Ir based devices are more stable at high temperatures and have a higher sensitivity than Pt and this is related to the higher oxygen coverage of the surface. However, these results are taken in a 5% oxygen background.

IEEE Sensors poster extreme gas

Waiting for questions at the poster

This afternoon it was the poster session and so I spent the afternoon fielding questions about our work on high temperature HfO2 dielectric sensors. This seems to have attracted a good level of interest and two hours flew by talking to a wide array of people. Hopefully some of this interest will be followed up with some interesting collaborations for the future. As for now, it’s the end of this part of the day and it’s off to Thomond Park, the home of Munster rugby club for the gala dinner, once we get ours glad rags on.





IEEE Sensors Day 1

29 10 2011

A great start to the conference. The opening plenary by Prof Julian Jones from Heriott Watt University was a good introduction to the development and application of fibre interferometry, including work he has undertaken in photonics crystal fibres. This includes the use of photonics crystal fibres, which allow the transmission of longer wavelength light, even though the core is still fabricated from silica. These have also been used to sense hydrogen, by use of a palladium coating.

Then it was a full session looking at gas sensors. This year, there is interest in non contact techniques, such as the one demonstrated by Martin Eickhoff, which used GaN and InGaN nano wires to investigate the concentration of explosive gases, with a sensitivity to hydrogen of around 50ppm at 80C. This was followed by our paper on DNA templates Pd nano wires, which is available in one of the previous posts.

DNA templated Pd nanowires sensor

Alton in the middle of the presentation at IEEE Sensors

This was followed by another talk on hydrogen sensing using WO3 nano particles and carbon nanotubes, before I went off to watch a couple of talks on energy harvesting, following on from the work Simon completed for his thesis.

After a coffee break, the gas sensor talks continued, with the first two concentrating on the use of graphene to form sensor arrays, with the intention of realising electronic noses. The graphene in these two presentations comes from the chemical reduction of graphite oxide and is then dispersed in water, prior to application to the electrodes. The sensitivity of this type of graphene is high, because of the functionalisation of the surface and the high defect density. One interesting fact from these talks is the use of CuO to detect acetone, something which is not possible using a graphene alone. After this, two talks on the development of silicon carbide sensors, which were interesting and showed an improvement on previous work in this field. This was achieved in the main with significant signal processing of the results, and as a result it is possible to identify the concentration of gas species. This has the potential to be a critical enabling step in the quest for commercial applications of SiC gas sensors.

The last talk prior to lunch, was reporting on the 1/f noise of gas sensors, something which we may well consider for our SiC devices in the future. The trend shows a different shape, as well as magnitude, with different gas species and concentration. This is thought to be linked to the adsorption / desorption of gas from the surface of the sensor.

After lunch, the posters. The majority were not related to our interest in gas sensors, so it was a chance to catch our breath in time for the final talks of the day. An interesting session, which discussed the suitability of langasite as a suitable material for acoustic sensors in high temperature environments. Apparently this is available commercially and it appears that it might make an interesting piezomaterial for high temperature energy harvesting.

Not bad for the first day, and there’s still two more to go!





Sensors presentations

25 10 2011

Two presentations finished for this weekend. The first is the oral presentation on the development of Pd nanowires on a DNA template. The sensitivity of these is higher than those grown using alternative techniques and is substantially easier, as it is a self assembled bottom up technique. A pdf of the presentation can be found at IEEE Sensors 2011 – Paper 1457. The other presentation is Ben’s work looking at the mechanism behind gas sensing in high-K/SiC (IEEE Sensors – Poster 1421 – Ben), where we show that HfO2 dielectrics are insensitive to oxygen. This is a key step in us understanding the basic physics behind our target of building an array structure in SiC. The poster has been printed by the reprographics team here in the University, who have recently added the capability to print onto canvas, which means I can fit it into my suitcase and avoid the excess charges for a poster tube on the plane. It’s also cheaper than buying a ‘normal’ A0 paper version and having it laminated!





Sensors Conference !

20 10 2011

The next thing on the horizon is the IEEE Sensors conference, which is being held in Limerick at the end of next week. We’ve got a couple of papers in, we are in the first session (Gas Sensors I) on Saturday morning at about 9:30 and then in the Gas sensing poster session on Sunday at 1:30.

As well as the opportunity to present our sensor work, this is a great opportunity for us to find out what everybody else in the world is up to, make some new friends and even identify a suitable external examiner for Ben, who should have his thesis finished in the next few months.

Whilst the hotel and the city look really inviting, the hectic conference schedule means that I’m sure all I’m going to see over the weekend is the inside of the conference hall! Hopefully, updates will appear on here as we go, so that everyone can see the highlights.





And now for something completely different …

6 10 2011

One of the great joys of being our PGR director, is that the job involves supporting the students in what they want to do, as well as persuading them to conform to the University expectations. As part of this, yesterday we had our (first) annual team building day, where the decision was taken to summit Catbells in the Lake District. In what can only be described as ‘typical Lake District weather‘ thirty of us managed to brave the conditions to stand at a height of 451m, in the middle of some stunning landscape.

PhD trip Lake District Extreme weather

Lucy sees the funny side as she finally gets some direction from her supervisor during her PhD

This seems to have been a popular choice and on the way home, there were requests for another day out and the chance to have a go for ‘something bigger‘ next time. In the meantime, we are claiming to have set a new world record, having 29 PhD students on top of a Lake District mountain at the same time!