Synthetic microswimmers, or active particles, are micro-scale objects that are capable of converting available energy, e.g., stored in chemical “fuel” or harvested from external sources, into directed motion. They are often thought as model systems for biological microscopic swimmers and have been offering new insights in the behavior of matter out of thermodynamic equilibrium. However, most synthetic microswimmers to date have been obtained from a very limited space of design parameters, and hence exhibit a limited range of functions compared to biological entities or larger machines. The challenge to expand the design space is then coupled to the incorporation of new materials and the development of new fabrication strategies, which enable programming and controlling the response of active particles under different conditions.
After a general introduction, I will propose two strategies that we are currently exploring in our laboratory. First, I will show that by choosing a photo-conductive coating that changes electrical conductivity under UV illumination, we can obtain Janus swimmers with programmable motility within light patterns. I will then show that the incorporation of thermo-responsive polymers, combined with the precise positioning of adaptive elements in the design of microswimmers, i.e., via directed assembly or nanoscale printing, enables the realization of reconfigurable microswimmers with multiple dynamical states, which are programmed during fabrication.
The rapid advancement in micro and nanoscale fabrication techniques and the ever-growing palette of available functional materials reveal an exciting future to develop complex active systems with programmable responses.
References:
[1] L Alvarez et al., Nature Communications, 12:4762 (2021)
[2] S van Kesteren et al., Proceedings of the National Academy of Sciences USA, 120 (11) e2213481120 (2023)
[2] S van Kesteren et al., Advanced Materials, 2207101 (2023)