Speeding to a supercapacitive polymer

Materials World magazine
1 Mar 2018

Gary Peters talks to Dr Maria Asplund, from the Department of Microsystems Engineering, University of Freiburg, Germany, about the SPEEDER project – a plan to create a supercapacitive polymer.

Tell me about your career so far.

I studied applied physics and electrical engineering in Sweden. After that, I was unsure what to do, so I started a PhD focusing on materials for neural interfaces, within the nervous system.

I was looking at new electrode materials for those applications and discovered the BioOrganics Electronics Group in Sweden, led by Professor Olle Inganäs, working on conducting polymers. I spent five years travelling between Linköping and Stockholm, to develop materials for neural stimulation. After that, I went to the Freiburg Institute of Advanced Studies, Germany, and later the BrainLinks-BrainTools Centre of Excellence, also at Freiburg.

What are some of your career highlights? 

My reason for coming to Freiburg was to develop conducting polymers with different functionality, but I didn’t have access to any devices, or know anyone who could make the actual probe.

At Freiburg, I worked with the group of Thomas Stieglitz/Biomedical MicroTechnology, and they are experts in making soft and flexible implants.

We started a study in 2011, when I joined, which was published in 2017, to investigate what I thought was a very simple question – if one functionalises the material with an anti-inflammatory drug and releases it around the implant, can you reduce inflammation around it? 

The material, in principle, we had, but we had to learn how to fabricate the probe, and with animal experiments we had to learn how to perform and analyse the results. I’m very proud that we got it all together.

Where did the idea for SPEEDER originate? 

It was when I left Stockholm. I started looking into the electro migration concept with a colleague who worked with metal electrodes and wanted to see if they could be used to accelerate migrational cells. 

While looking at this, I figured that the conducting polymer materials I already had were suited to the purpose. However, I left for Freiburg and didn’t have time to focus on something completely new. In a low-intensity way, I have been pursuing the topic for the last couple of years, as a side project when I have the time.

More recently, we have seen that it is possible to control migration of cells with electric stimulation. It took a long time to set up, but once you have the equipment in place, it’s relatively easy.

What are your objectives?

The idea is to use the electromigration function of cells, in particular skin cells. If you stimulate them with a direct current or an electrical field, they align their movement and migrate along the field lines. This is believed to be how cells find their way across a skin wound.

When a wound heals, the cells migrate to cover it. The concept that I propose is that one can accelerate this process by applying external stimulation. But for this you need another kind of material, and that is where we have a conducting polymer-based gel electrode. But, can we make polymer gel electrodes? We start with cell cultures to understand how to control cells with our system, before proceeding to more advanced models and then, hopefully, harvest biopsies and stimulate those, so we don’t harm anyone in the process.

What timescales do you have?

It is a five-year project. We believe that the cell culture work is very important and we need to complete a lot of mapping to figure out which stimulation signals to use to get the best possible response from the cells. 

We also need to understand those that do not have an effect and those we can use to recharge our system so that we can apply stimulation for a long period with some intermediate pulses to recharge our electrodes.

The project began on 1st February 2018.

You’ve received funding of €1.5m from the European Research Council – how will that help you drive the project forward? 

I’m really excited that now we can finally begin the project. The money is critical in setting up something like this.

We will be able to work on more dedicated materials development. We know that the base for our materials will be the polymers, but the grant means someone can invest time in figuring out what type of polymer composite will provide the best efficiency.

It also gives me the chance to hire people with different expertise and skills. I’m an engineer, but I’m not a biologist, so the wound healing part is outside my expertise. I will hire someone for this, who will help me in setting up cell culture models, to replicate the real function of human skin. We will able to test our ideas on real human skin, which would not be possible without getting an expert on board.

What is the next step for you?

The most crucial part at the moment is recruitment. I need to bring more people in – such as a microsystems engineer to work on device design, and someone with chemical expertise to work on the materials side. 

We will also buy more equipment for live imaging of cells over several days. We need the right equipment and a lab where we can build this up. 

What are some of the challenges you have faced to date?

In the faculty where I work, space is always an issue, with many competing projects. This is a challenge that can be easily forgotten.

Right now, we are working towards our first publication. We are trying to put our data to together to show it is possible to control migration, in this case of cancer cells. This is the pre-study before the wound healing project starts.

The polymer would also be used to aid the healing of wounds?

That’s correct, and to accelerate healing. Most people with a wound don’t have a problem. Most wounds are small and people have a good ability to heal naturally, but it’s different if someone has, for example, diabetes, or if a wound is large. Healing can take time, meaning infections can occur, leading to a chronic wound.

That’s what we’re focusing on – difficult wounds and people with reduced healing efficiency.

So, the polymer stores the energy and releases it when necessary?

Yes. It will also have a recharging protocol. Since the cells respond at a certain threshold, sometimes they don’t respond to the field, meaning we can work with stimulation above the threshold to guide the cells, and reverse the stimulation to refill the electrodes, below the threshold. 

We can also have periods where we push the cells and others when we don’t interfere with their natural behaviour.

You plan to incorporate the polymer as a component in electronic dressing – is that the end goal of your project?

This is what I imagine. When you think of wound dressing, ordinarily it’s a textile-based system, but ours would be more like a device, using medical materials from neurostimulating devices, such as making active wound dressings out of silicone rubber.

Is there anything else that is similar to your work?

There is technology for stimulating wounds, but in this case they don’t have good materials for delivering direct current. It is very often a pulsed current of some kind. It has, to date, been difficult to prove the clinical effect of the guiding of the cells.

What are your set targets over the five-years?

We have defined goals for the coming months and first couple of years, but towards the end – depending on how well we do in the short term – we can be more or less ambitious with how far we go. 

The first thing is to set up the cell culture systems to use different materials and test many parameters in an efficient way.