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Soft and Biomatter Theory


Admission Requirements

There are no special requirements for those admitted to the MSc programme Research in Physics. We however expect you to have taken statistical mechanis and classical mechanics courses, and be comfortable with tensor notation, partial differential equations and Fourier transforms. You should also have basic programming skills.


In soft matter physics we study physical constituents with interactions that are weak enough (often of the order kT) that the matter is easily deformed, hence soft or squishy, and at scales from about a micron and up where quantum mechanics is irrelevant. Many soft matter materials and concepts are relevant for biology, and we will specifically also consider active materials which are internally driven.
This course will provide an introduction to several key soft and biological materials and phases, and to the most important concepts to describe and analyze them. In addition, we focus on the general applicability of techniques and concepts, and to connections with other areas of physics.

The core of the course is formed by 11 lectures of two hours. Weekly additional exercise classes will deepen your understanding and train you how to do practical calculations or estimates yourself.

The course broadly follows 'Soft Matter: Concepts, Phenomena, and Applications', by Wim van Saarloos, Vincenzo Vitelli and Zorana Zeravcic. Additional material and slides for the whole course as well as exercises and solutions will also be provided.

Topics covered:
An introduction to fluid mechanics and to elasticity theory
Life at low Reynolds numbers and application to cells, colloids and microfluidics
Brownian motion of particles in a fluid, leading to the Langevin equation, fluctuation-dissipation theorem, and the Smoluchowski equation.
Introduction to Colloids; forces between colloidal particles. Active Brownian particles and active colloids.
Introduction to the physics of jammed and glassy materials.
The physics of polymers, and application to biopolymers.
Liquid crystals, including the Frank free energy, topological defects, and active nematic materials

Course objectives

After completion of the course you will be able to

  • gain a broad overview of the existing soft and biological materials and what the focus of ongoing research is.

  • understand the context and line of reasoning in a research paper in the field.

  • critically discuss the concepts and material treated in the course using a blackboard or whiteboard.

  • be able to apply the concepts and techniques introduced in the course to your own research problems

  • derive intermediate steps in a line of reasoning and carry out theoretical calculations with the broad range of techniques introduced in the course and exercises


Physics Schedule
For detailed information go to Timetable in Brightspace

You will find the timetables for all courses and degree programmes of Leiden University in the tool MyTimetable (login). Any teaching activities that you have sucessfully registered for in MyStudyMap will automatically be displayed in MyTimeTable. Any timetables that you add manually, will be saved and automatically displayed the next time you sign in.

MyTimetable allows you to integrate your timetable with your calendar apps such as Outlook, Google Calendar, Apple Calendar and other calendar apps on your smartphone. Any timetable changes will be automatically synced with your calendar. If you wish, you can also receive an email notification of the change. You can turn notifications on in ‘Settings’ (after login).

For more information, watch the video or go the the 'help-page' in MyTimetable. Please note: Joint Degree students Leiden/Delft have to merge their two different timetables into one. This video explains how to do this.

Mode of instruction

See Brightspace

Lecture and tutorials (5 mandatory exercise sets); a text book, slides and additional materials are provided.

For the exercises, the students are asked to form teams of maximum three students, who will work on the exercises together. How the teams do this is up to them, last year some teams worked closely together on the exercises, others mostly compared noted after each team member worked on the exercises individually. Once a team has finished the exercises, the team sends the solution to the Teaching Assistant, who then discusses the solutions with the team in an online or physical meeting of about half an hour.

Assessment method

The assessment is based on two parts:
1. Active participation in the class and the exercise class. Specifically, we ask that students attend the weekly tutorials and hand in a minimum 4 out of 5 exercise sets, and show that they have made a credible effort at solving those sets. This will count for 30% of the grade.
2. After the course, students will take an oral exam, at a mutually agreeable date in May that fits the student's schedule and preferences. The oral exam will be in person and will take about an hour, and is in the spirit of an informed discussion in front of a traditional blackboard about the course material. This will count for 70% of the grade.

The aim of the oral exam is to test whether you have studied and grasped the material covered in the syllabus. This does not mean, of course, that you need to memorize everything in the syllabus – in fact, you should feel free to take the syllabus or any notes with you to the exam. Think of the exam more as an intelligent discussion about the concepts that were treated in the course. We will use a blackboard or whiteboard, and I might show you some experimental data to discuss these with you in the light of the material that I covered. The exam is in a relaxed atmosphere and we hope that you will actually learn from the oral exam. A soft matter colleague will also be present at the exam as a second examiner.

PhD students who take the course only for pass/fail do not have to do the exercises.

Reading list

The course material will be covered in slides and additional notes, homework and solutions as well as programs which the students can obtain online in Brightspace.
We will broadly follow 'Soft Matter: Concepts, Phenomena, and Applications', by Wim van Saarloos, Vincenzo Vitelli and Zorana Zeravcic, to be published by Princeton University Press in early 2024.


As a student, you are responsible for registering for each course component. This can be done via Mystudymap. You do this twice a year: once for the courses you want to take in semester 1 and once for the courses you want to take in semester 2.

Registration for courses in the first semester is possible from July onwards; registration for courses in the second semester is possible from December onwards. For more information, see this page

Please note that it is mandatory for all students to register for their exams. This can be done up to and including 10 calendar days prior to the exam or up to five calendar days in case of a retake exam (retake registration opens 30 days before the retake takes place). You cannot participate in the exam or retake without a valid registration in My Studymap.


Lecturer: Dr. S.E. Henkes


Transferable skills

After completion of the course you have gained enough background to independently learn about these topics from the specialized literature.