Start & Introduction

 

Andreas B. Dahlin

Disclaimer:

This is a personal webpage created by me. It does not necessarily reflect the opinions and policies of the University I am affiliated with.

 

Copyright ©

Andreas B. Dahlin

Welcome!

Welcome to my research website! Please browse through the content using the menu. Links to social media where I am active are also shown.

Looking for work?

I am always seeking contact with students that are motivated and talented. If you are interested in working with me do not hesitate to contact me. Recruiting a Ph.D. student requires a lot of funding, but it happens. Postdoctoral positions may also be announced. (Postdocs that can come with their own grants are of course particularly interesting.) All positions will be announced on websites and in my Twitter timeline. Please note that the only type of positions that can be announced are either doctoral student or postdoctoral researcher. I cannot accept "visiting students" or "interns" etc. As an undergraduate student, you are welcome to discuss the possibility to do your thesis work with me.

Disclaimer regarding emails:

Due to the large number of emails I get I cannot promise to provide an answer to every one. It sometimes simply takes too much time. This holds for applications from students, conference invitations and various requests for help. However, I will still check your email even if I do not reply to you. Please do not feel dicsouraged to contact me!

Contact:

adahlin@chalmers.se

 

 

 

 

 

 

 

 

 

 

 

 

 

 

My Research

The aim of this part is to present an overview of my research at more of a popular science level.

My research interests belong primarily to three major research subjects, namely nanotechnology, soft matter and molecular biology. I see myself somewhere in the overlap of these fields as I work with biointerfaces (where biology meets the artificial) and nanoscale devices. One could perhaps summarize this as "BioNanoScience" (although this sounds dangerously close to "biononsense"). I have studied chemistry and mollecular biology as an undersgraduate, while my Ph.D. was done partly in physics. My expertise is now mainly in biophysics, polymer physics, surface chemistry, nanofabrication, electrochemistry and optics. Most projects I work with are strongly interdisciplinary as they contain physics, chemistry and biology. This requires bringing together people and information from very different research fields and combine them into something new. I enjoy this kind of creative science and I think this is where my strength lies. Of course, this approach to science means that I will not really become a specialized expert on any subject and I rely to some extent on collaborations with other scientists who can provide expertise on different aspects on my projects.

Much of my research is quite fundamental in nature. My aim is then simply to advance science and improve our understanding of reality. However, I am also motivated by finding applications of my results that could be useful for humankind in various ways. For instance, I am interested in how my research could improve biosensor and so called lab-on-a-chip technologies.

Functional Nanopores

Most of my work relates to nanopores in one way or another. To put it simple, I work with very small holes. I am far from the only one in the world working with nanopores, but my nanopores are quite different from those typically produced by other research groups. Conventional solid state nanopores are normally single apertures in thin insulating membranes, while my structures contain many pores (arrays) in multilayers of materials, including metals. This is what gives the structures unique properties. Even among those working with nanopores in metal films I have profiled my activities through the use of special such pores.

In order to fabricate nanostructures, nanopores included, one must somehow define a pattern on the nanoscale. This can be achieved by two different approaches, either by directly "writing" the pattern, normally by an electron or ion beam. (Light beams cannot be focused to small enough spots.) The other approach is to use some kind of self-assembly, i.e. to let nature do the job. My nanopores are created by self-assembly of colloidal particles which makes the process very simple, especially if one wants to make many pores over large areas. In subsequent steps, a number of thin film depositions and etching steps are used to generate the final structures.

By using thin metal films I can incorporate several detection techniques that can be used to analyze and manipulate molecules present inside the nanopores. The metal films can be used as electrodes which makes it possible to implement electrochemistry and resistive heating (like a hotplate). Further, one can excite so called surface plasmons (a light wave confined to a surface) in the thin metal films and use them for optical detection of reactions on the surface. This is simply accomplished by shining light directly on the nanopores. A certain wavelength (usually visible light) will then couple to the surface plasmon and less light of that wavelength will be transmitted. To put it simple, the color of the surface will change.

Macromolecular Gates

We are all used to having doors that control who can enter or leave a room by the assignment of some form of keys to those individuals. I am interested in achieving the same thing but with molecules instead of people and on the nanoscale. This work is inspired by the highly specific nanoscale gates (doors) found in nature, such as the nuclear pore complex which controls what molecules are allowed to enter the nuclei of eucaryotic cells (where the DNA is stored). By functionalizing my nanopores with polymers I hope to achieve the same type of selective barriers that only allow a selected target molecule to pass, which opens up for applications in separation technologies. It could be a way to tackle the vastly complex mixtures of molecules one faces in biology. I am also interested in making nanoscale gates that can be opened and closed by electric signals, i.e. just by pressing button. (Active rather than passive gates.) This can be accomplished by using special polymers that undergo shape changes in response to changes in temperature or the chemcial environment.

Biosensors

Although I am spending more time now on the development of macromolecular gates, I still have some activities related to biosensor development and several publications from past work. (This is where I started my research career in 2004 with the use of plasmonic nanopores for detection of biomolecules.)

Biosensors are devices designed to detect or analyze a molecular interaction where the receptor, which captures the target (analyte), is biological in nature. The most known biosensor is the glucose sensor for diabetics, which detects the glucose concentration in blood by the use of an enzyme and electrochemical readout. Another example of an everyday life biosensor is the pregnancy tests that detect a certain hormone in urine samples. In contrast to the glucose sensor which is quantitative (one really wants to know how much glucose there is in the blood) the pregnancy test is "digital" (yes you are pregnant or no you are not). The dream scenario for research on biosensors is that we can make cheap and realiable devices that detect rare and important targets in complex mixtures. For instance, if one can detect ceratin rare proteins in blood (biomarkers) this can lead to diagnosis of diseases and monitoring of treatment efficiency.

Many biosensors are in fact not used to detect a certain target in a sample, but rather to analyze an interaction between two molecules in a controlled manner. In molecular biology and drug development it is of great interest to determine the affinity between a pair of molecules, how long they remain bound together, how their interaction varies with temperature and so on. One way to investigate these aspects of an interaction is to immobilize one of the molecules on a surface and introduce the other molecule in solution. If the surface is such that it gives a detectable signal upon molecular binding one can analyse the interaction in real time and without artificial labels. This is the principle of surface-based biosensors. My nanopores represent one type of surface capable of such analysis by optical spectroscopy or electrochemical readout.

Electronic Paper

In a recent sideproject, we have started to develop a new kind of reflective display, also known as electronic paper (like the Kindle reader from Amazon), in color with ultralow power consumption. More information will follow depending on the outcome of these activities and if funding is obtained. A small startup called has been launched:

 

 

 

Here is my popular science presentation about electronic paper at the Science Festival 2017: