What AFM probe type do you need most?

As many of you know, I'm really keen that as a company we're working in tandem with the needs of the AFM community. 2018 is all about expanding our product range and we need you!

We'd really appreciate if you could fill out this really quick, 1-question only survey, letting us know what type of AFM probe you'd most like to see us develop next.

We're already able to offer the Scout 350 model of general-purpose AC-mode silicon AFM probes, suitable for non-contact/tapping modes in air, on hard samples and stable softer samples. Additionally, we also have our NuVOC range of ultra-soft probes for use in vertical orientation instruments.

You'll have also seen our new Scout 70 model of AFM probes, a general purpose AC-mode silicon AFM probe, which can now be applied to high resolution imaging of soft samples. In case you missed the product release last month, you can still read about the different versions of the Scout 70 here.

Our production team are packed with ideas on the different types of probes we could develop. You input in our survey will help shape our focus for the next few months. I really appreciate your help with this.

 
cleanroom
 

New Year, New Product

The New Year is traditionally a time to make resolutions, set goals for the year ahead and embark on new challenges. It's no different here at NuNano HQ, and we're kicking off things with a new product!

The new probe means that our consistent tip sharpness and minimal variation of mechanical properties can now be applied to high resolution imaging of soft samples.

The Scout 70 is a general purpose silicon AFM probe for imaging in AC modes (non-contact/soft tapping) and force modulation, with a nominal 2 N/m spring constant and 70 kHz resonant frequency, making it ideal for imaging delicate samples or objects that are loosely adhered to their substrate surface.

With two other variants, the Scout 70 is also available as Scout 70 HAR with a high aspect ratio tip for deep trench imaging. The Scout 70 T, with its lower resolution tip, is perfect for step height measurements and getting new AFM users started. All probes are available either uncoated or with reflective aluminium coating on the backside of the cantilever.

Our new probe allows users to access a lower force regime whilst maintaining the same high standards of reliability you've come to expect from our other products.

Applying our proprietary manufacturing process to our Scout 70 probes has meant we've been able to achieve the same tight dimensional control of the cantilever, which in turn ensures there's less variation in the mechanical properties of our probes.

 
SEM image of our new Scout 70 probe

SEM image of our new Scout 70 probe

 

About Scout 70 AFM probe Model

The Scout 70 model of AFM probes have been specifically developed to provide the same exemplary dimensional tolerances and tip sharpness characteristic of all our AFM probes. Click on the links below for more detailed specifications and pricing:

  • Scout 70 - general purpose AC mode silicon AFM probes, suitable for non-contact/soft tapping and force modulation modes in air, on softer samples. Spring constant: 2 N/m. Resonant frequency: 70 kHz.
  • Scout 70 HAR - as above, but featuring a high aspect ratio tip with a cone angle over the last 1 μm of less than 15 degrees.
  • Scout 70 T - a lower resolution version with a tip radius of between 10 - 40 nm, perfect for training new AFM users and for applications where price is more important than tip sharpness.

As with all NuNano products, the Scout 70 model is compatible with most commercially available AFMs. For harder samples, including stable softer samples, our Scout 350 model is also available.

I look forward to announcing further product developments later in 2018, and as always I'm keen to hear about the AFM imaging challenges that you face as that gives me a real drive to help support the AFM community.

For more information, to request a datasheet, free sample, or if you'd like to meet with me to discuss your needs further please call +44 117 299 3093 or email info@nunano.com

Season's Greetings: 3 things you need to know when setting up a scientific company

December is a short (and busy) month for everyone, so we'd simply like to take this opportunity to wish you all a very warm and happy winter break. See you in 2018.

(For those of you still in the office for whatever reason, why not grab a cuppa and have read of my article 'How to build a nanotech company' published in this months Nature Nanotechnology. In it I've shared my three top tips on what you need to know if you're thinking of setting up a scientific company. As always let me know your thoughts and your top tips below!)

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5 top tips for effective AFM imaging: a beginners guide

The atomic force microscope is an amazing device. I remember the first time I ever used one, I was completely blown away by what I was able to see.

But I also remember that they can seem pretty quirky things until you get a bit more familiar with them. Using one is a lot like learning to drive - the learning doesn't really begin until you get out on the road on your own. It's then that you discover the nuances of driving, when everything your instructor had to remind you to do becomes second nature.

 
Caution, learner driver!

Caution, learner driver!

 

In real life, hands on experience of working with an AFM can be as daunting as taking your first car out for a spin. Often students and post-docs can find themselves nudged towards the AFM by their supervisor or peers. Wide encouraging smiles and nods of heads suggest that if they just crack on they'll soon get the hang of the thing. And they do.

But here are my five top tips to make the first couple of rides out with your AFM a bit less bumpy for you...

1) Sample prep - it's really important that you are highly disciplined when preparing your sample. You need to make sure that you repeat the same steps each time. If you deviate in your prep, there's a good chance that it will interact differently during imaging, which will affect what you're able to see with the AFM.

2) Know what you're expecting/wanting to see - You need to have a good understanding of the probable dimensions and shape of sample features and structures BEFORE you start. What width and height are my features? Are they evenly distributed across the sample or sporadically clustered? Then set your parameters on the AFM accordingly. Having the settings wrong can result in long hours of futile effort with little reward. 

3) Pick the right probe for the job - the right probe will depend a lot on your sample, and the choice of probes available can be daunting. The first thing to consider is the sample material, then choose a probe that will maximise imaging resolution and stability whilst not damaging the sample. Standard AC mode silicon probes (for tapping/non-contact) will be perfectly fine for imaging a wide range of materials in air, but things get tricky when the sample is softer or when imaging is performed in liquid. Then what about surface topography - are we talking salt flats or alpine peaks? A probe with a high aspect ratio tip might be needed to image the bottom of a trench. The list goes on. If you're not sure what you need then give us a call. We're always willing to offer advice.

Final word regarding probes - always consider whether the probe is brand new or if it's been used before, and don't underestimate the amount of contamination there can be in a laboratory environment. I would always advocate using a new probe if you want those perfect images for a publication.

4) Are you aligned correctly? - You need to make sure that you've aligned the laser spot on the end of the cantilever (as close to the tip as possible). Sounds simple, but for new users, not familiar with the construction of an AFM probe, it's all to easy to get a good laser reflection on the detector but not actually be reflecting off the cantilever. Knowing the size and shape of the different components of the probe (upside down of course) is crucial. Aligning the laser at the end of the cantilever will give you the best sensitivity.

 
For best imaging, the laser should be aligned at the very end of the cantilever.

For best imaging, the laser should be aligned at the very end of the cantilever.

 

5) Practice makes perfect - When you start driving, you can't expect that the first time you get behind the wheel of a car you'll drive perfectly and effortlessly arrive at your destination in good time. Likewise, when you start out working with your AFM don't expect to get perfect images first time. In fact a lot of the scientific insights arises from the problem solving, figuring out why you're not seeing what you think you should see and changing your process accordingly. Keep at it and you will find that you become much more attuned to how the AFM and your sample are interacting. And, when it doesn't work you can quickly identify what the underlying issues might be.

Doubtless this will all make using AFM sound a bit fiddly but when you started driving a car it probably felt like there were a million different things that you had to think about all at the same time. Now you check your mirrors regularly as a matter or course and don't have to consciously remember 'mirror, signal, manoeuvre' etc.

If you're already an experienced user then this is all pretty obvious, but whatever your level of knowledge and skill please feel free to print this out and stick it on the wall (near the AFM...) to help those less familiar with using the instrument.

And as ever we'd like to hear from you - what are your top tips for working with AFM? What was your first experience like? What is the one piece of advice you always make sure to pass onto first time AFM users?

(With thanks for the input from Dr. Rob Harniman, Technician in Atomic Force Microscopy, School of Chemistry, University of Bristol, UK)

An interview with Professor Mervyn Miles

In this month’s blog I caught up with NuNano co-founder and director Professor Mervyn Miles to discover not only where his fascination with microscopy and high-speed imaging came from, but also where he thinks the next exciting areas of research are to be found...

 
Mervyn Miles is Professor of Physics at the University of Bristol, as well as Chief Scientific Advisor to the Institute of Physics Publishing and a Fellow of the Royal Society.

Mervyn Miles is Professor of Physics at the University of Bristol, as well as Chief Scientific Advisor to the Institute of Physics Publishing and a Fellow of the Royal Society.

 

How did you get involved in microscopy?

It’s funny because I never set out to work with microscopes. My PhD actually focused on understanding polymer samples and for the first part of my career, understanding and predicting the structure of polymer samples remained my main point of study.

During my time at Birmingham University, I was granted access to a million electron volt (MeV) electron microscope.

Now in the normal course of things polymer samples tended to get destroyed after a couple of seconds in electron microscopes operating in the 100 keV range. Not with this one though!

Using the mega-volt microscope, I could see all sorts of pretty diffraction patterns. My sample looked almost as though it was on fire in dark-field imaging. I couldn’t believe what I was seeing, that it was possible to see this much detail without killing the sample.

From that point on I was hooked on microscopy and imaging - though at that stage only because it was a fascinating tool to facilitate my polymer research.

So a key part of your polymer research was around accessing the best possible imaging equipment?

Yes, you could say that. I went to Germany to do my post-doc in synthetic polymer physics studying under Herbert Gleiter[1]. He had a whole new way of looking at polymers, again using electron microscopes[2].

He was an amazing guy to work with, really inspirational. He had a constant stream of ideas and treated everyone as an equal despite the fact he was working on some complex stuff and cutting edge ideas. In many ways I internally absorbed his way and pattern of working.

During this time I obtained some pretty interesting images, showing the nanoscale structures of polymer fibres produced under elongational flow stretched single molecules[3].  I showed these some years later at a conference which was attended by Andrew Keller, a polymer physicist working at the University of Bristol.  Keller was pretty impressed with what we'd achieved, which sorts of shows that it was ground-breaking stuff we were working on.

After I completed my post-doc in Germany I went to Case Western Reserve University, Cleveland, Ohio, which at the time had the best polymer department in the U.S.  That was a totally different experience to working with Professor Gleiter.  The guy I worked with in the Department of Macromolecular Science had great drive, but his focus and strength was in co-founding and building this department from the ground up, rather than the science.  He pretty much delegated the running of his quite substantial research group to me.  So I learned a lot quickly - many different projects needed data interpreting and new ideas and new directions.

After just one year in the U.S., I started my first period in Bristol.  Prof Andrew Keller, who founded the field of polymer physics, had told me that if I ever wanted a job to contact him.  It was time to cash in this offer! In that move, I did two very different jobs: transmission electron microscopy of polymers and elongational flow of polymer solutions to understand the nature of individual molecules in solution and what happen when they were stretched out by the flow field.  This all went very well, but after three years it was time to find a ‘proper job’ rather than another post-doc position.

My next move, still focusing on polymer research, was to Norwich, to work – rather bizarrely – for the Institute of Food Research. They had loads of money to do basic science which in turn meant we weren’t constrained in the science we could do. Though ideally the sample should be edible!

Our head of division was a fascinating enigmatic guy called Henry Chan. He moved so quietly around the place he would suddenly appear at your shoulder whilst you were working and say, ‘you’re in trouble Miles, …. Big trouble’.  I never found out if I really was or not. But brilliant. He was the person who first introduced me to and encouraged me to work with the new science of scanning tunnelling microscopy (STM).

Nobody really knew what it was about of course. Even at the European Bioscience Physical Congress, held in Bristol in 1984 – a huge conference with many parallel sessions including one on x-ray microscopy. I found myself making small talk with a chap needing help to find the building for the next session, I asked him was his area of research was. He told me about this esoteric technique where a sharp piece of wire is brought within an Angstrom or so of the sample surface and the quantum mechanical tunnelling current is measured as it is raster scanned over the sample. I thought this would never work because of the mechanical stability and control precision that would be needed. This was of course scanning tunnelling microscopy for which he, Heini Rohrer, and his colleague Gerd Binnig would be awarded the Nobel Prize in Physics two years later, and with the help of Prof. Sir Mark Welland in Cambridge, I began the change in direction in my career to this technique.

Through Dr. Chan’s and Dr. Morris’s encouragement I took one of the protein molecules I had been studying with small-angle x-ray scattering (SAXS) and deposited on an x-ray mirror’s surface, amorphous carbon, and looked at it via the STM with Mark Welland. It was pretty amazing. Through the images we obtained, we discovered the 3D structure the STM was showing us of individual molecules was as I had predicted from SAXS - we got one of the first pictures of a single protein molecule[4].

When did you start getting involved in the development of instrumentation?

By this point I was increasingly interested in the latest and best developments in microscopy.  My focus was on improving the substrate for immobilising biomolecules rather than the tool itself though.  I was always looking for the best substrate materials.

In 1989 I moved back to the University of Bristol, again working with Prof. Andrew Keller.  I was supposed to be working on x-ray diffraction and scattering, but clearly STM was going to be huge, so I applied for an STM grant immediately I arrived in Bristol and we were awarded it in April 1990. This meant we finally had our own STM to play with!

Around this time one of my undergraduate project students built a scanning near-field optical microscope (SNOM) which achieved the best resolution of anywhere in the world and this is really where developing instruments came in for me, from around 1990. This is the photon analogue of STM.

Shortly after that, I put in for a grant and got an Atomic Force Microscope (AFM). I recruited a post-doc, Terry McMaster, from Norwich, and we began work on AFM of biomolecules.

One from the archive... The Bristol SPM group in 2000, celebrating Mervyn's inaugural lecture.

One from the archive... The Bristol SPM group in 2000, celebrating Mervyn's inaugural lecture.

So when did you start your first company?

When I was awarded a personal chair, that is, promoted to professor at Bristol, I decided to do something different. I began work on developing holographic tweezers and also started a company: Infinitesima.

We produced and sold a product called Activ Q which helps to control the quality of factor of the cantilever and is very important in liquid for improving image quality in liquid. We sold quite a few which was encouraging. One of the key issues for a while had been around improving imaging quality and stability in liquids.

We started trying out ideas to increase the speed of imaging, initially in SNOM, where we managed to increase the frame rate 100,000 times.  We then wanted to try this for AFM, which would have far more applications.

Amazingly it worked – and even more amazingly the speed was critical to it being able to produce great images in liquid (see figure below for a recent example of our high-speed AFM imaging). If we had turned the speed up slowly we probably wouldn’t have continued along this route because it turns out that at a slower speed the sample continues to be destroyed! Another one of those, ‘let’s give it a go and see what happens’ instincts that turned out well!

So where did the idea to set up NuNano come from?

It was about ten years after I’d started Infinitesima. Frustrated by the varying quality of existing AFM probes, we thought maybe there was an opportunity to make improvements. It was the brain child of my colleague and co-founder Heinrich Hoerber. The mix of what seemed to me to be a great idea with the enthusiasm and drive of former PhD student and post-doc James Vicary made setting up the company a no-brainer.

James has done a brilliant job of implementing the idea and turning it into a successful product.  And, importantly developing out from that original idea to produce the kind of game-changing probes that no-one else is working on yet, such as the ultra-soft high-speed vertically-oriented probes (VOPs).

What excites you about the future of nanotechnology and what’s the next area of research you’re most interested in?

I think the use of high speed VOP force microscopy in true non-contact mode, with zero normal force, on living cells will make a major impact.  The ability to see signalling, transport and whole changes in structure at the cell membrane will give exciting new information.

Using the high speed vertical probes for example, as I have done lately with work I’ve been doing around Alzheimer’s, just makes you realise how much more there still is to be explored in the world of force microscopy.

Imaging membranes at high speed means you don’t end up making holes in the lipid (and thus destroying the sample). We’ve produced the most amazing images of membrane samples where you can actually see the Amyloid proteins destroying the membranes.

It's exciting and important work and we're looking at ways to go beyond just imaging.

High-speed (left) and normal speed (right) AFM images of the same area of a model multi- lipid component neuronal membrane. The contrast corresponds to the slightly different height of each lipid.  Such membranes are very soft, almost liquid-crystal-like, yet the disruption by the high-speed tip is surprisingly almost non-existent.  Image courtesy of Morgan Robinson & Zoya Leonenko (University of Waterloo, Canada) and Loren Picco, Ravi Sharma & Mervyn Miles (University of Bristol, UK).

High-speed (left) and normal speed (right) AFM images of the same area of a model multi- lipid component neuronal membrane. The contrast corresponds to the slightly different height of each lipid.  Such membranes are very soft, almost liquid-crystal-like, yet the disruption by the high-speed tip is surprisingly almost non-existent.  Image courtesy of Morgan Robinson & Zoya Leonenko (University of Waterloo, Canada) and Loren Picco, Ravi Sharma & Mervyn Miles (University of Bristol, UK).

[1] H Gleiter, “Nanoglasses: A new kind of Noncrystalline Material and Way to an Age of New Technologies?” Small 12 (2016) 2225–2233

[2] J Petermann and H Gleiter, “Direct Observation of Amorphous And Crystalline Regions in Polymers by Defocus Imaging”, Philosophical Magazine 31 (1975) 929-934

[3] MJ Miles,  J Petermann & H Gleiter, “Deformation Mechanism of ‘Hard’ Elastic Fibres’, Colloid & Polymer Science, 62 (1977) 6-8.

[4] ME Welland et al., "The Structure of the Globular Protein Vicilin revealed by Scanning Tunnelling Microscopy", International Journal of Biological Macromolecules, 11 (1989) 29-32.