A camphor boat is one of the famous self-propelled particles, which moves spontaneously on the water due to the difference in surface tension around the boat.

The collective motions of the camphor boats resemble traffic jams and the quorum sensing in living things, and the camphor boat has been studied as an example of an active matter in non-biological systems.

Furthermore, the camphor boat has been interesting topics as bifurcation phenomena, where the behaviour changes drastically at a certain value of the parameter.

When an elliptical camphor disk, with the center of mass fixed at the axis of rotation, is placed on the surface of water, it rotates spontaneously.

We found the appearance of the bifurcation from the stable state to the rotational state in the control of the water depth. The bifurcation type, which is subcritical bifurcation or supercritical bifurcation, depended on the aspect ratio of the elliptical camphor disk.

We discussed the important factor to determine the bifurcation type through the results of our experimental results and our phenomenological model.

Many biological systems contain material components that are repaired and replaced over time by accompanying cells. One common example is the extra-cellular matrix, an interconnected network of proteins that provides chemical and mechanical protection and support in many systems, such as tissue basement membranes and bacterial biofilms. Questions remain as to how the bulk mechanical properties of the material depend on cell maintenance. I will present a spring-based model that aims to capture how the microscale replacement of elastic material can give rise to different observed bulk mechanical behaviours. Despite the model’s simplicity, it has a number of interesting characteristics that are biologically-relevant.

Modelling thermo-responsive hydrogels can be a challenging task – the physics that underlies the rapid deswelling that occurs when temperatures cross a critical threshold is hard to characterise, and the transition from a swollen to a deswollen state involves the transport of fluid through the pores and the elastic deformation of the polymer scaffold left behind. In this talk, I will outline a new model for thermo-responsive gels that makes the physical processes behind deswelling straightforward to model and can reproduce all of the phenomenology seen in much more complicated energy-based approaches. This new model allows for the development of single-component displacement pumps that can drive flows of water through their lumen in response to pulses of heat, and we can deduce the optimum geometry for maximum pumping rates using the quantitative predictions that it provides.