Venice euspen Conference

The weather forecast was electric storms for the duration but each day it was sunny spells and hot and the forecast had changed to be electric storms starting the following day.  It didn’t start until our last day on Friday.  We were glad of the aircon in the venue for the euspen conference in the end.  Our first challenge was that the conference was being held in a building near the ports which is a 15 minute walk from the main bus station and Venice.  The accommodation (Jolly Campers) we were allocated was not actually in Venice and was therefore not covered by the 3 day pass we were bought for transport.  Jolly Campers did provide a shuttle bus that dropped us near the port but it only started at 9 am and last but 9 pm which was not suitable for us mostly as the lectures started at 8.30 am and finished around 5 pm but we also had dinners and other functions so could rarely catch the last bus.  Also, you had to buy tickets in advance.

 

 

We started our week with a welcome drinks session that was in Venice but unfortunately, we arrived too late for the workshops we had chosen in the afternoon.  The welcome session was great and helped everyone adjust and start to network a little.  To find the event, Saurav our course director, used google maps while taking pictures of the journey with his selfie stick.  Once the event had closed we all scooted off to find a suitable venue for us all to eat in a restaurant.  Many people that know me will know that I’m famous for saying, “There are no restaurants in Venice”.  I say this from previous visits because most are really tiny cafés with many seats outside.  The only real restaurants are the ones in hotels.  I can categorically state that I was wrong, there are very many really good restaurants in Venice and we found one with an internal courtyard to accommodate all 15 of us.  Four Mres from Cambridge, eight from Cranfield, our two lecturers, Saurav, Claudiu and lastly Adam, who did his Mres at Cambridge and transferred to Cranfield for his PhD.  Adam is a great guy known by most at Cranfield for his hard work, knowledge and helpfulness.  He is finishing his PhD this year but may still be around next year on another project.  You can find the full team of Mres students here, https://www.cdt-up.eng.cam.ac.uk/directory/mres-students.  We were spread over two round tables that paid their bills independently.  We enjoyed our meal but were a little surprised when the bill came.  Although we hadn’t requested, bread sticks and bread rolls came out and we hardly ate any of it.  This turns out to be standard all over Venice, they always add a cover charge per person including, bread, place settings and napkins etc.  They sometimes also include a service charge.  Unfortunately, many of our table had left, paying for what they had first which of course didn’t include their share of this charge.  As we had to pay for the bread rolls, Katherine being a vegan, struggles sometimes to find suitable food, took these rolls in her handbag on top of the receipt.  It was hilarious when the waiter asked for the receipt to check it, to watch Katherine taking the bread rolls out of her bag in front of the waiter to get the receipt.  This alone, made it worth the charge!

 

Being our first return journey at night with no transport tickets, we did well negotiating a bus journey and 45 minute walk to eventually find “Jollies”.  We even managed to get the last drink in the bar to replace fluids.  The following morning, I was down for breakfast around 7.30 which was a sparse buffet breakfast but adequate and free.  As long as we have hot and cold drinks and a small snack we are happy.  It was a very long day Tuesday at the conference but also really enjoyable and informative.  There were also people we had already met on the CDT program from other events.  euspen gave everyone a small rucksack on registration that had various goodies inside, including a program that listed all the presentations with times and a few lines about each paper presented at the conference.  Prof Richard Leach, from Nottingham University, whom I had been for an interview with for my PhD presented five papers at this event alone.  Now I understand how he has managed to be involved with over 250 papers prior to this event.  He is a legend and certainly “the man of the moment”.  Euspen also included a usb stick that included all these papers.  What a great start.

 

Breaks, followed presentations, that followed breaks until it looked like we would have time to walk to the bus station to convert our travel card barcode onto a real card and maybe even take a couple of pictures of Venice.  However, there were some awards that we felt it would be rude if we didn’t attend followed by short talks from all the exhibitors at the event.  To get the most from talking to the exhibitors, it seemed we should listen to these also.  Two of our group walked to convert the travel cards taking our barcodes with them so at least we could use them from now.  We had already missed almost the entire first day of the transport but we had them anyway.  Once these talks were finished euspen had laid on a student networking dinner that didn’t finish until 10 pm.  This was very nice but we felt that we should at least have seen Venice.  Once we realised there would be no time we arranged to take the following afternoon off because we had not been invited to the formal dinner that evening anyway.  Following the hour long lunch was one of two, 2 hour poster sessions where we could read the posters and ask questions about the owners projects.  There were two from Cranfield resenting posters, Rita (an Mres) and Adam just finishing his PhD.  We explained to them what our intensions were but they had to be by the posters for both events and they agreed to meet us following this session.  We could all then attend the important final poster session where the votes were counted and prizes awarded.

 

We had a wonderful time around Venice, starting by getting the boat to Murano where they have made glass since at least the 1400’s.  In fact this is where Galileo bought his glass that he made the first telescope with in Venice.  I had missed it on all of my previous visits but finally made it there.  The glass is very expensive but beautiful and probably the best that money can buy.  However, these days it’s likely that most of it is first imported from China.  We visited the Murano glass Museum which was expensive but enjoyable.  Not sure why the museums in Venice are so expensive; it’s a shame as I fear many people do not go in because of costs.  We walked to the nearest ferry port and returned to Venice main island – next stop St Marks Square where we were to meet Rita and Adam following the poster thing.

 

On previous visits, the square has been so packed I have not enjoyed it there but this day it was reasonably clear with people feeding the pigeons.  People think that pigeons are fat but they are not, they just have very large breast muscles that allows them to be the only bird that can manage a vertical take-off.  Dileep turned out to be bird man and every time he put his arms out they seemed to land on him.  Dileep only likes the girl pigeons landing on him.  He is from one of my favourite places in the world, India and so is self-funding.  He works incredibly hard without complaint, doing everything we do plus manages a 40 hour week working in a local petrol station.  He also never misses an opportunity to pitch for funds towards his PhD.  Remember the course fees for international students is two to three times as much as for home students.  He cannot get funding from home without first returning to India for two years before he will qualify.  Anyway, we met the other missing students and split up because the Cambridge guys had been invited to the formal dinner and had to head back.  There were a few missing because Venice flu seemed to hit our group from day one and some were in the rough early stages in bed.  The remaining Cranfield students agreed to walk to the Rialto bridge which is probably second on the list to St Marks Square.  We were starving and settled for the Rialto Restaurant right next to the bridge.  Man, now we were living, I had a huge 1 litre jug of beer and the food was very good and not as expensive as most places.  Its so expensive in Venice as its almost all tourists and they don’t have to impress because new tourists will be along all the time.  Once finished we started the long walk back to the bus station followed by a 15 minute walk back to Jollies.  They had a pool party on that night that finished at 11.30 pm.  Sounds good but we are living in caravan rooms that are semi detached and can hear every noise outside.  Once the band had finished they seem to play music until 1.30 am most nights and my neighbour always rose at 6 am.  This shakes the caravan around so much you can’t possibly sleep so it was late nights and early mornings every day.  Still this meant that I was always one of the first down for breakfast.

 

Thursday was another long day but the main event was the poster competition and were pleased when that finally came around.  We asked Rita many difficult questions which she was very able to answer and of course we all voted for her.  Adam was magnanimous in encouraging everyone to vote for her even though he was entered himself.  I asked Adam for his poster number so I could vote him second but he wouldn’t let me as any votes for second and third are effectively voting against your first place.  PWAO2154The announcements; third place was awarded, then second and finally first place out of around 250 posters.  Rita’s real name was announced (Junguo zhao) and her face was a picture – she was so shocked but the roar that went up was incredible, everyone was going mad. Yahoo, well done Rita!  Her parents are going to be so proud and well-done Adam for his part in this victory and honour.  This is the event that Saurav won when he did his Mres, not all that long ago and now he has over 40 papers published.  The event finished around 5 pm so we all left for dinner following Tommy from Cambridge who had eaten at an impressive place a short walk away previously.  Unfortunately, it was already full by the time we arrived there so we headed off, eventually finding a larger restaurant in a square with enough spaces to accommodate us all.  They pushed lots of tables together so it all felt quite medieval.

 

On Friday we had a choice of three industrial tours but again the logistics didn’t really work as we were so far out.  Fortunately, Jollies had an eight seater minibus that we booked.  They only had one so we had to do two trips.  As it started raining at 5 am our first group had to stand in the rain until the others arrived.  Different minibuses arrived for tours one and three but a full sized bus turned up for our most popular number two.  Number two was an excellent tour around a university.  They split us into 3 groups and each was let around five departments.  It all worked so smoothly and run by intelligent people.  As usual Dillep took the opportunity of asking for PhD funding.  The university had some great equipment and were working mainly on trouble shooting for industry, solving any problems that arose by trying to understand the problems.  Understanding is the only true way forward – there is no point just being lucky to find a solution.  If you truly understand something, you can design whatever application you like from it, if you were lucky you only have one solution.

 

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Bra Bar

The afternoon was free and again we wandered around Venice, but this time without the aid of google maps so we kept finding dead ends.  We headed towards their Natural History Museum but they wanted 24 euros each.  We found two other museums but again, as students they were too expensive.  We eventually found ourselves at the Rialto bridge again and crossed back onto the normal side where we ate at the restaurant last time there.  This time we used google maps to find the famous bra bar that my friend Evonne had told me about in a Facebook comment.  It was literally two minutes from the bridge.IMG_8469  We had a drink there but prices were quite high – even for Venice.  Following this drink we set off to find the others who had eaten at the restaurant we couldn’t get in previously.  They had already left but amazingly we bumped into most of them walking by a market.  Strange how these coincidences happen, with all the people in Venice how we should meet this way.  We all went for a seat in the shade in a local park following Tommie’s expert guidance once again.  By now the rain had stopped and the sun was back in force.

 

We were not all on the same flight home for our return, the Cambridge gang were flying back from a different airport to Stanstead while we were at Marco Polo to Gatwick.  Today they has a staff strike at the airport that ended at 5 pm and our flight was at 9.50 pm.  However, we spent most of our time queueing because of the backlash.  Again, when we arrived at Gatwick we must have taken a couple of hours to meet at baggage claim.  We finally set off finding the minibus for our return but the M25 have overnight roadworks and is down to one lane at 40 mph.  We got to the M1 to find it was closed between the M25 and Milton Keynes so had to drive around the houses to get back to Cranfield.  By the time I got home it was just past 3 am and I seemed to be developing a sore throat.  The dreaded Venice flu, so I took a lemsip before going to bed.  Awoken by a phone call at 8.30 am, I still felt tired but two more lemsips seemed to keep the cold at bay.  What a fantastic trip which was also educational and interesting and we all managed to get several contacts for our PhD projects which I will talk about in a future blog once I have accepted my best choice offer.  Only two weeks away from our next conference in Edinburgh.  Where am I going to find the time to finish my Mres thesis properly?

 

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Mres Thesis – CuNi Nanowire Synthesis

I have been so busy, first completing assignments and more recently doing research on my thesis.  I had a short holiday to Ethiopia which has been the only blog I have had time to do for ages.  I started my research work upon my return from holiday.  It’s a great project but not really playing to my strengths as its wet chemistry.  Although I love all science, chemistry is probably my weakest link.  I was quite good at it at school and I did a little during the early years of my OU degrees.  I have read quite a few chemistry courses that were not assessed from the university library.  Anyway, I feel like an alchemist in my white coat, safety glasses and blue gloves, hovering over bubbling glassware.

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Modern electronic devices require a transparent conductive layer which are made from Indium Tin Oxide (ITO) currently.  This works perfectly, being very transparent to visible light while being highly conductive.  The main problem being that Indium is very rare and has been estimated to only last another 10 years at current use but is growing fast.  This makes it hugely expensive and the prices fluctuate wildly with the stock market which is not ideal for commercial enterprise.  The greatest problem though is flexibility, ITO is non-flexible while flexible electronics is growing fast the race for an alternative is fierce.  Thousands of people all over the world are currently researching into practical alternatives, from metal nanowires (NW’s), carbon nanotubes (NT) etc.  So far silver NW have proved themselves as a real alternative but again, expensive.  Silver NW’s are flexible and do not oxidise readily so where flexibility is required these are generally used.  Most research however, is being done by synthesising Copper NW’s (Cu NW’s).  The biggest problem is that Cu oxidises.  We don’t worry about the Cu wires in our houses oxidising so why worry about the NW’s oxidising?  It’s a matter of scale; the oxide is only very thin, a matter of nanometres.  This doesn’t affect thick wires of 1 mm diameter or more but when the NW’s are only a few tens of nanometre diameter it becomes a serious proportion of their bulk and also the outside where they must fuse to make a continuous conductive layer.  Most of the research has concentrated on protecting them from oxidation but covering or plating.

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Background

My research is the continuation of a post-doc research by the very good chemist Quentin Lonne at Cranfield University two years ago.  He was researching into Cu NW’s but near the end of his work discovered that by the addition of a little glucose into the mix, it made some of the nickel compound, instead of acting as a catalyst, combine with the copper compound to make CuNi NW’s.  He also found that as little as 3 % Nickel was enough to inhibit oxidation enough for a practical solution to replace ITO.  On the negative side, as some of the Ni combined with Cu to become a compound, it was not doing its job properly acting as a catalyst and making the NW grow longer so very short aspect ratio NW’s were produced.  I was lucky enough to continue this work that looks so promising.

Objectives

My main aim was to increase the aspect ratio from around 175 to 400 or above by changing various proportions and synthesis cycle times and temperatures systematically.  As nobody really properly understands how Cu NW’s grow in a single direction instead of as a cubic Chrystal, my secret aim is to try to better understand this process.  Copper is a face centred cubic FCC that has equal dimensions on all sides so what is making it grow anisotropically instead as a cubic Chrystal?  Of course, we know how to do it and which organic compounds must be incorporated into the mix to inhibit growth in the other directions but I have not read an explanation that makes sense to me.  Of course, I have read dozens of related papers already; you have to when doing research.  That’s the main reason why I haven’t had time to catch up with the blog.  Once a decent aspect ratio have been achieved, my next objective is to optimise the opto-electric properties so that the concentration is good enough to make a good conductive layer while not stopping very much light and so be transparent.

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The method

I am using a one pot chemical method to synthesis the NW’s from scratch without the addition of nanoparticles.  To do this, I have a heat cycle that first synthesises nanoparticles, then the heat cycle is changed to synthesize these particles into NW’s.

There are only 3 chemicals used to synthesise Cu NW’s, copper II chlorate dihydrate, nickel II acetate trihydrate and oleylamine.  The oleylamine is thought to inhibit growth in all directions except the direction of growth, the nickel compound acts as a catalyst and the copper comes from the copper compound.  With the addition of glucose, some of the nickel is incorporated to make CuNi NW’s.  I have synthesised NW’s between 65 % Ni to less than 1 % Ni.  The chemicals are mixed together in a 50 ml glass bowl with a magnet inside.  The mixture is heated while being stirred to around 100 °C and held for 30 minutes then heated to around 200 °C and held for another 30 minutes to synthesis the nanoparticles.  The stirring is stopped and held at this temperature for around 16 hours while the NW’s grow.  Quite a simple process that is not very labour intensive.  The work comes the following day when the organics are to be scrubbed from the wires.  It’s a very hard day cleaning following a synthesis but it has to be done the following day otherwise it all conglomerates together into a lump.  That means that synthesis take 2 days.  It is possible to synthesise the next batch following cleaning the first batch so I can do a maximum of 4 syntheses a week.  Therefore it is important to analyse the NW’s quickly to enable a sensible change for the next weeks syntheses.

Post Processing

First the NW’s have to be dried and then mixed with ink to the correct concentration.  This can be spread onto a substrate such as PET or glass where the ink dries.  The next step is curing the NW’s so that they electrically fuse together.  There are many methods but I am mainly using a heat treatment method at 350 °C for 3 hours so has to be done on glass.  Copper has a melting temperature of over 1000 °C so the NW’s are not melted together.  Many strange things happen when you do things at the nanoscale.  Also, its at this scale that quantum effects start to kick in.

Once the glass slide has been cured it can be measured for conductance and transmittance.  This is why a large aspect ratio of NW diameter to length is so important because the longer the wires the more likely the overlaps so the lower the concentration can be and the thinner the NW’s the more light can be let through.  Obviously, if the NW’s overlap, the thinnest coating possible is 2 times the diameter of the NW’s so the surface finish is directly proportional to the diameter of the wires.  There are alternative methods to curing the NW’s, one I have also tried is Ultra Violet light exposure.  Unfortunately, I have not managed to get this method working yet so will be ordering a new bulb or lamp.  Keen to get this method working as it’s such a time saver, instead of 3 hours cooking, you only need in the order of two minutes exposure.  It will also enable the slides to be on PET rather than glass and so be suitable for Roll to Roll (R2R).

Results and future work

graphOriginally, I had such a bad start, it was hard to believe but it seems to be getting better at last and I have had very mixed but interesting results.  I have already exceeded my target of an aspect ratio of 400.  That means that the length is at least 400 times the diameter of the NW’s.  My best result is 751.  However, I feel that my target was a little low because the definition is that the length should be at least 1000 times the diameter to qualify as a nanowire.  The better the aspect ratio, the better the optoelectronic properties and surface finish.  However, we don’t want the NW’s too long because it causes problems when applying by inkjet.  More favourably than increasing length, to reduce the diameter, especially as oxidation should not be such a problem.  Hannah, one of our speakers from Cambridge, who is growing gold NW’s mentioned that the diameter of her introduced nanoparticles was roughly the same size as the finished nanowires.  If this is true for Copper, I have a method of reducing the diameter size.  I therefore require a method of measuring the nanoparticles during synthesis.

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The above setup should enable me to ensure the nanoparticles as they grow and therefore be able to predict my desired size of nanoparticle synthesis time.  There is a rubber cap over one of the entry pipes which I can insert a syringe through to extract some of the nanoparticle solution.  This self-seals and doesn’t allow air in.  I could do this at regular intervals throughout the synthesis to find exactly what is happening and should also satisfy my thirst for understanding this process.  It should also enable me to try other ideas.  One I have is to initially grow copper NW’s and then inject glucose dissolved in a little more oleylamine to coat the Cu NW’s with a little CuNi alloy coating for protection while keeping them as conductive as possible.  If this method works and I have time, I feel confident that I should be able to both understand the workings and solve the problem.  Trouble is, time.  We have a week away at Venice for the EUSPEN conference first week in June and another week in Edinburgh last week in June.  Also, the date to have our thesis handed in is in August.  Better get cracking, exciting times ahead!

Student led Conference IfM Cambridge

The week following the Industrial tour was our Conference, that I must admit, the Cambridge students did the lion’s share of organising.  Shame, because there are only four of them and 8 of us but I guess that it couldn’t be helped as it was held at Cambridge.  Anyway, thank you guys for another really enjoyable day out.  We all had jobs for the day and I was to look after the Speakers to make sure that they didn’t drink to much before their speeches.  This was perfect for me because it gave me chance to get to know these geniuses early on and be more able to talk to them throughout the day.  Also, my Daughter Georgina took a day off and traveled from London to attend as a guest.  Mohammad was also coming via London so I send them both a picture of the other in case they spotted each other at the station.  Unfortunately, the London train was cancelled and left them scratching around trying to recover but they both arrived eventually.

 

 

Cranfield laid on a minibus and driver for us which was really appreciated.  We set of at 6.30 am so as to miss the dreadful Cambridge traffic which worked and we were first there at 7.30 am.  We couldn’t even get in the building.  A quick cup of tea and the others started to arrive so we set to work preparing the speakers PC and putting posters up.  We had arranged 5 exhibitors, Aerotech, Advanced Chemical Etching, Bronkhorst UK Ltd, Physik Instruments Ltd and Potter Clarkson LLP.  These all set up in our lecture room with a capacity of well over 100 and we only had about 80 register.  We took a couple of PhD students along from our building 70 and it was just as well because 30 attendees didn’t turn up.

 

Dileep looked very smart, I’m sure that his family back in India will be very proud of him.  Dileep is self funded and works at the local petrol station 40 hours a week to keep his education going.  He is the first in his family to leave India and is desperately trying to get funding for his PhD because overseas students pay 3 times as much as local students.  Any wealthy generous people reading this blog that would like to donate to Dileeps future or research please get in touch, he specializes in nanotechnology in the Bio-industry.   First up was Dr Hannah Joyce from Cambridge who talked about gold nanowires.  I was particularly interested as my current research is synthesising copper nickel nanowires (more in next blog).  Hannah was followed by Prof Graham Machin from NPL and then Prof David Walker from Huddersfield and we had our first break.  The speakers were getting behind schedule so someone printed a 5 minute warning sheet with a 1 minute on the reverse in red.  It was my job to show this at the relevant time.  It didn’t help because I was giving the warning 5 minutes before the next speaker was due on so the questions always took us over time.  Once I switched to 10 minutes before the next speaker we were able to pull it back a little.

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Following break we had Prof Peter Childs from Imperial College London who I spoke to about family history because my Mother’s maiden name was Childs which I traced back to 1701.  I traced some other family back to 1539 which I was pleased about at the time but would like to start it up again now we have so much stuff online.  Peter was followed by Dr Petros Stavroulakis from Notts University.  Petros replaced prof Richard Leach who I will mention again in another blog but couldn’t make it last minute.  The final speaker of the morning was Prof Xichun Luo from Strathclyde University.

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Tanya had put on an amazing spread but about 3 times more than we could eat, which pleased the hungry gannets that were hovering around waiting for us to leave.  The first speaker of the afternoon was Dr Manish Tiwari from UCL.  George had asked Manish along as he was his supervisor in his undergraduate degree and he holds him in very high esteem.  Dr Athina Markaki was the speaker before the afternoon break.  Athina is also from Cambridge and spoke about 3D printed body parts which I found particularly interesting as this was my recreational reading area prior to starting this course.  In the afternoon, we had Prof Michael de Podesta also from NPL and Dr Grigorios Riga from M-Solve.  It was all finished off with wine outside.  What a way to finish of such a fantastic day.  When I can talk to people like this, I just feel like I have arrived home for the first time.  People that are as nerdy and geeky as myself.  I love it and in a just over a weeks’ time we will have a week of it as we are all attending a week’s conference at Venice put on by EUSPEN.

 

We all had a really long but enjoyable day.  Our minibus was coming back to collect us at 6:30 pm but luckily we had some wine and juice left.

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Industrial Tour

What a week, thoroughly enjoyable, I always like it when the twelve of us get together.  Well, we had 10 of the 12 for the tour as two were unable to make it.  It was a little here, there and everywhere, I don’t think that whoever organised it had much logistical training or encountered the “travelling salesman problem”.  We started around Oxfordshire visiting companies such as, “Oxford Instruments Nanoanalysis” (who were in High Wycombe), M-Solve (more on these in a later blog), Rutherford Appleton Laboratory. Integration Technology and Renishaw.  Of course, all relevant to our training.  We stayed in a Travelodge that was sometimes 2 hours’ drive from our next destination.  But as we were all together, we had a great time.  George (from Nicosia Cyprus) was driving the “Boom Box” that sometimes we all travelled in when we were back to the same accommodation as the previous night.

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The first night we travelled into Oxford for a look around the university and a beer.

On Tuesday we started with the Rutherford Appleton labs, which was one of my favorites.  We started by touring around ISIS which is a particle accelerator that accelerates neutrons and Muon’s into a target (electron cyclotron).  Then we visited Vulcan and Gemini which was the most powerful laser in the world (in 2005) and produces power up to 1021 W/cm2.  This is equivalent to the total energy received from the Sun by the Earth and concentrating it to the size of a “full stop”.

Renishaw was another great tour.  They are the CMM specialist but normally make probes.  However they showed us their new CMM machine which has broke the mold of this type of instrument.  Normally, companies build these machines very heavy and strong and mount the whole thing on a giant block of granite but Renishaw’s new machine is lightweight and can therefore move very quickly.  They have concentrated on total mechanical separation rather than reducing the high frequencies transmitted through the ground.

Renishaw’s grounds are huge and they have an innovation centre where they are geared up for tours such as ours.  Next stop at the manufacturing and Technology Centre in Coventry.  We were given the afternoon off as we had to drive up to Durham.  Generously, CPI took us all out for dinner on Thursday evening at the Dunn Cow in Sedgefield.  This is famous because Tony Blair took George Bush there for dinner when he came over (see cover picture).

They certainly saved the best until last, CPI Netpark showed us around their printable electronics facility in the morning and then their Electronics and Graphine facility and then their Biologic s facility at Darlington in the afternoon.  The main purpose of CPI is to help businesses scale new products up for manufacturing, not to invent new products.  It is part funded by the government and non-profit making so they can pitch at sensible prices for up and coming companies.  They use both top down and bottom up processes and is a really nice company with VERY clever people working there.  What a place, they seem to be the perfect mix between academia and industry.  We started with a virtual reality demonstration which I really enjoyed.  It was like the old fashioned adventure game that used text except in 3D vision where we had to negotiate ourselves around a factory processing a part in the correct order for the correct times and chemicals.  Its a really useful training tool for training people at dangerous processes safely.

What a great week, I enjoyed everything except for the long drive home.  Quite dangerous following a long day and long week; especially on a Friday evening.

 

Scanning Electron Microscope

I have always wanted to use a Scanning Electron Microscope (SEM) and my chance came last week at Cambridge University.  What a thrill.  I received an optical microscope for Christmas one year as a child and had endless fun and excitement with it, but the SEM is a whole new ball game and has a resolution down to 1.4 nm.   That’s a thousandth of a micron or a millionth of a millimeter. Hard to imagine.  To add to my excitement, it also had a focused ion beam (FIB) microscope adjacent to it that we used.  I didn’t even know what they were until a few days before we used it.  Its similar to the SEM microscope but fires ion instead of electrons which are much bigger and heavier so can inflict more damage.  When the current is turned up, you can machine or mill the sample in a very controlled and accurate way.  We also injected gas molecules (organic platinum) between the sample and the FIB.  If the current is just right, it won’t machine the surface but rather split the platinum from the organic part of the molecules and deposit them on the surface of the sample.  Because you have the SEM pointing at the same place you can look at what you have done.  I want one!

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SEM with FIB at 54 degrees

You don’t think of a microscope firing a current, but that’s exactly what a current is, a flow of electrons.  To get an idea of how many electrons are being fired at the sample; A Coulomb = 1 Amp per second.  The charge of a single electron is around 1.6 x 10-19 coulombs so there are 1 / 1.6 x 10-19 = 6.25 x 1018 electrons per second for 1 Amp.  We have a typical probe current of 200 pA so there will be 6.25 x 1018 x 200 x 10-12 = 1250 million electrons per second or 1250 electrons every μs bombarding the sample.  Just shows how unimaginably small they are and how many of everything must move before we can even notice it.  Of course, the FIB also fires a current, just not the negative electrons rather the positive part of the atoms that are left once some electrons have been stripped.  They usually use Gallium ions because it melts below 30°C.  Its solid at room temperature but melts in your hand, unlike treats (now called M&M’s).  A proton weighs 1.6727 x 10-24, a neutron about the same at 1.6750 x 10-24 and an electron 9.110 x 10-28 so a proton is 1837 times heavier than an electron.  Gallium normally has 31 protons and normally 39 neutrons in its nucleus.  It therefore normally has 31 electrons in orbitals around the nucleus but if the electrons are stripped from the outermost shell (valance) it will become a little smaller and be positively charged.  Because only one electron is in the outermost shell of gallium it will have exactly the same charge as an electron but be positive rather than negative (1.6 x 10-19 coulombs).  So, each ion in the FIB will carry the same charge as each electron in the SEM but weigh about 1837 x 70 = 128,590 times as much.  So, you can imagine how much more momentum and damage a beam of ions can do to the sample surface compared to electrons.  That’s the same difference as an average man (70 kg) compared to a freight train with an engine and 63 loaded rail cars.

We started by measuring the features on a DMD (Digital Micromirror Device) using the SEM.

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Image of DMD mirrors

The mirrors are about 13 μm square with a Ø1.5 μm hole and the gaps between the mirrors are about 1.1 μm.  So surprisingly we could get an array of 100 x 100 or 10,000 mirrors in a square of 1.3 mm on the side.

Well a DMD chip has several hundred thousand microscopic mirrors arranged in a rectangular array on its surface; each of which correspond to a pixel in the image displayed.  Each mirror can be individually rotated by around ±10° which represents an on or off state.  When on, light from the projector is reflected off the mirror, through a lens onto the screen as a bright pixel.  When off, the light is directed to a heatsink, so the same pixel appears dark.  To produce grey, the mirror is toggled on and off very quickly by pulse width modulation, so the shade of grey corresponds to the ratio of time on to time off.  To produce colour, three coloured projectors and three mirrors are required for each pixel and the ratio of on to off for each colour determines the pixel colour brightness.  The mirrors are made from aluminium and are mounted on a yoke which is connected to support posts by torsion hinges.  Because of the small scale, hinge fatigue does not usually cause a problem.

We did a few more experiments, carrying the acceleration voltage and the probe current etc, and then changed the sample for an EPROM and set up the FIB.  If you set the distance an M stage tilt correctly, its possible to be able to view the same part of the sample with the SEM and the FIB without changing the focus or moving the sample.  This is called the Eucentric point.  Below is the same image using both devices.Compare

TrapYou can see that the SEM is viewing the sample at an angle but there is a tilt correction mode if you like.  The resolution and contrast of the SEM is so much better than with the FIB.  Next we drew a trapezium on the sample that we were to mill out by setting the accelerating voltage and current just right we got a really nice cut of 3 microns deep.D200pSEM

We found the optimum current to be around 200 pA.  Its amazing how accurate and easy it is to machine the sample; this image is taken at 4000 times magnification.  The maximum optical lens you can use is about 1000 times.  This is just run of the mill, its capable of far greater magnification if you like.  When looking at biological samples, they have to be stained with a rigorous process prior to viewing so that the different tissue types stand out and can be seen.  When looking at anything else, you just put it in and focus; and the images are so much better than the ones I could get on my optical microscope as well.

GISOur next step was to inject a gas between the FIB and sample when it was scanning.  The gas we used was made from platinum organic molecules.  If everything is set correctly it will split the gas and deposit the platinum part on the sample while the organic part is vented away.  This time we drew a small rectangle on the sample as it takes a while.

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Platinum deposit on EEPROM

We then decided to do the same cut, half on the deposit and half off.108

We noticed some funny furry deposit at the front of the cut so zoomed in for a closer look.Fur

This view was taken at 8200 time magnification and we could have gone in much further.  We then moved onto our last part where we analysed the surface at different places to do a spectral analysis and find out which elements were present.

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Spectrum of area around the cut out and deposit
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Summary of elements at various places

The redeposit column was taken on the furry deposit which was found to be made up of platinum, silicon and carbon.  Basically, everything that was blasted away when the cut was made.  Its interesting that there is so much carbon around; I think the only place that could come from is the organic part of the gas which should have been vented away.  Not quite sure how it gets vented away anyway as everything happens in a vacuum and to vent away you need a lower pressure than where it is.  Well, you don’t get much lower pressure than in a vacuum.

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Image inside vacuum chamber

Sorry its been so long since my last post but I have been so busy I cant tell you.  We have lectures all next week at Cranfield then the following week at Cambridge and then no more!  So once I have written up the reports for those I will only be doing my thesis so should have more time to catch up with everything else that has happened.  I will get there in the end.

Cambridge Week 2

Again, we set of about 7am and again we hit traffic miles from Cambridge.  It was even worse this week so we didn’t get there until 9am, just time for a cup of tea and for everyone to copy my data stick of data and pictures from last week.

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Tea in the canteen before we start
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Katjana Lange

We started the day by trying to catch up with what we missed last week.  We eventually got through it all but it was already lunchtime.  Now only the afternoon to complete the entire days’ work.  Lilly helped us again with our catch-up work in the morning and Daniel for a while in the afternoon.

Daniel brought Katjana in to talk to us as her PhD is largely

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Actual laser cut

about laser ablation which we are working on.  Very enlightening – Kat’s short talk enabled us to better understand what we were supposed to be doing and to get on efficiently.  Today’s work was about measuring the laser cuts we had done last week so we could establish various properties about the laser power and focus etc.

 

 

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Catch up with Lilly

It was a very long day, especially as I had awoken at 4am and got up at 4.30.  We left IfM at Cambridge University around 6.45 and I arrived home at 20.10.  I had had to fill the car with petrol on the way home as tomorrow I need to take the hire car back and drive to Bedford to pick up my new car before driving to Cranfield University to continue lectures there.

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My new car

Cambridge University

Probably the best Science University in the World?

We decided to set off early as I know that traffic into Cambridge can be challenging.  I picked up Mohamed from Newport Pagnell first at 7am and went onto picking up Rita from her shared house in Cranfield.  Rita’s real name is, “Junguo Zhao”, but has chosen an English name because none of us can pronounce it.  Ren (Ren Guicun) decided to travel to Cambridge on Wednesday evening, to give himself a little tourist time.  Although the traffic was very heavy, we still arrived early at around 8.45am and parked on double yellow lines at IfM (Institute for Manufacturing) as nothing else was available.  We wrote a note which was left in the window giving my mobile number etc. and had a quick walk around the campus to take some photo’s.

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There are some very modern and colourful buildings along the road fronts with the old buildings behind.

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The Cavendish Laboratories are just down the road; this is Rita and Mohammad walking towards them.  When we got to the end of the building we bumped into Ran so our quorum was complete.

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Rita and Mohammad walking towards Cavendish Labs.

There were some notable street names, like J.J. Thompson Avenue and Charles Babbage Road etc.  Of Course, The Cavendish Laboratories is where Crick and Watson worked when they discovered the form and shape of DNA (National Association for Dyslexics).  There were too many famous scientists to mention but a couple, James Clerk Maxwell and Ernest Rutherford.  There were also 29 Nobel Laureates from these laboratories.

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Dan Gortat

We still arrived early and in time for a cup of tea and we were off for our first proper lectures.  I was also allocated a parking space so moved my car.  Today we have two laboratories about measurement (metrology) and we started by being introduced to two microscopes by Daniel, a Cambridge PhD student.  I met Daniel on our day out as I sat on the same table for dinner.  Daniel is at the end of his PhD and seems to be getting some stick from his peers as he is yet to start writing his thesis.

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Ran at one of the microscopes

I used to own a microscope when I was young as I pleaded with my parents to buy me one for a combined Christmas and Birthday one year.  They have changed so much since those days mainly because the lighting is so much better and we now have CCTV cameras so the image can be shown on a screen and manipulated by computers.  We didn’t even have calculators when I had mine.  The sample can be illuminated from the front with lights shining around the viewing lens or from behind like I had.  There is also an option to have the light at an angle to show cast shadows.

DSCF3081The post processing option opens a whole new world, for example, you can view samples in 3D by focusing on the top of the sample, then refocusing progressively lower saving each image.  The processor knows the focal heights and can stitch the images together enabling you to view the sample from any angle.

We over ran the morning session and therefore our canteen was closed so we had to walk to the West Café, just down the road towards the Cavendish.

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Lilly Delimarta

We were under pressure from the start in the afternoon when we were introduced to interferometry by Lilly a Cambridge PhD student.  I met Lilly on our day out at Cambridge because I sat next to Kryste, her thesis supervisor.

An interferometer microscope is for examining and measuring surfaces.  It works by splitting the focal beam, sending one beam directly to the viewing lens and the other via an adjustable mirror.  The mirror can be adjusted until interference bands can be viewed caused by diffraction.  As all setting are known, measurements can be calculated and interesting images and histograms created.

We were only about half way through our samples when we encountered a problem where the interferometer microscope seemed to view and measure the interference pattern rather than the sample.  Lilly couldn’t resolve the problem and brought in an expert, Andy Payne who I also met on our day.  Anyway, try as they might our problem remained unsolved when it was late and we all had to go home.

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Andy Payne

Andrew received his MPhys in Physics from the University of Kent in 2012 where his master’s year research was in Fourier domain optical coherence tomography. Subsequently Andrew joined the Centre for Doctoral Training in Photonic Systems Development and received his MRes from the University of Cambridge after conducting research into the coherence properties of liquid crystal lasers at Cambridge and the registration of 3D laser scanned point clouds at UCL.

We were booked into a Premier Inn only a mile or two away so we headed off and checked in.

DSCF3097To save money, Mohammad and myself were sharing in a “quad” room”, so we unpacked and tidied ourselves up and headed off to the restaurant attached.  Rita decided she wasn’t ready to eat and fancied a walk into the centre to have a look around.  By the time we had eaten it was 20.30 and we had no response from Rita when we knocked so went to our room to catch up on emails etc.  I emailed my computer written notes to the others.  I also took my new camera and will share the pictures once I remember a USB stick.

DSCF3098Our first night in Cambridge happened to be Harvest Moon so I took a picture of the

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Harvest Moon

Moon but it was drowned out by the street lamp.  Harvest Moon is the full moon that takes place closest to the Autumn equinox.  It used to be used to indicate when the crops should be gathered in to prepare for the winter months.  The full moon meant that work could go on later because of the extra light before we had street lights.

 

We all met for breakfast around 7.30 and could have as much as we liked from any menu.

DSCF3101We did our best and headed off to the University.  Today we were introduced to lasers by Dr Martin Sparks.

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Dr Martin Sparks

Martin is part of the Cambridge core team and is a senior research assistant.

Again, we all struggled, Martin talked and went through procedures at a tremendous pace and we all struggled to keep up while trying to take pictures and notes in unfamiliar topics.  As something had happened to the alignment of the equipment, we had to readjust the mirrors and equipment to get back in alignment again.  I am pleased that we had to go through this process because the alignment experience was a real help to understand the process.  Starting from the laser source we had to work our way through the system following the beam route adjusting as we went.  This meant that we had to wear special goggles, have the covers open and laser on while making these adjustments.

DSCF3112The main purpose of this Lab was to lead us into understanding the importance of documenting everything, thinking about things before acting and, “leaving no stone unturned”.  In research it is so important to document everything so that your work can be criticised and repeated to verify if necessary.  If anything is left out it leaves doubts over the validity of your work.  A good example of this was the research done into room temperature cold fusion.

DSCF3113This day was extremely stressful to us all as Martin left us to work so much out for ourselves.  At first, problems seemed insurmountable but gradually, maybe with hints, we got there in the end.  The harder things are to solve, the more fulfilling when they eventually are.

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Laser Goggles

In the afternoon, we had a sample that we could blast with the laser, doing experiments, varying power and other things so that these could all be examined using the microscope and interferometer next week.  We used G programming language to control the laser cutting process.  Two programs were given to us that we had to run, changing various variable, power etc. until the images of the cuts appeared optimum.  Again, we had two cameras focused on the workpiece that we initially set up.  One optical and one CCTV and both could be viewed on our computer screen.  The second program took moved the laser in a snake shape up the workpiece incrementally cutting deeper in variable steps.

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Snake

Once we had attenuated the power sufficiently that the image appeared optimal, we had to modify the program to cut in all four directions to enable us to compare the results of directional change next week when we measure these cuts.  My previous MSc experience came in handy here and I was quickly able to write a new section of code that would achieve this.  Again, we had to change variables and power etc. to optimise the laser cuts making it easier for us to measure next week.  The dots are where the cut height is changed and the red is the extra program cuts that we added starting at the deepest cut, incrementally raising so that adjacent cuts are the same height for comparison.

This time we finished ahead of time, but instead of heading home we decided to talk Lilly into helping us go through our missed interferometer lab.  She kindly agreed but we only had time to get through the third sample before she had to head off home.  We can go through our final sample before we start our lab next week.

I think I can speak for the others when I say that we all found this experience very stressful but once we were finished, quite a relief but fulfilling.  I feel so much better about this experience this morning following a great sleep.  For the past week, my sleep patterns have not been so good because of my excitement and anticipation of this course.  I now feel grounded and ready to go.  Before I can start though, I really do need to find and buy a car this weekend.  Also, it’s the Japanese Grand Prix.  Lewis just broke the, “total number of poles” record again which means that he has now won pole position at all the GP’s on this year’s calendar.  See you next Tuesday Cambridge!