Nanogenerators are devices that convert mechanical, chemical or thermal energy produced by a small-scale physical phenomenon into electricity . The technique can be applied in for example technology that requires self-powering without containing a battery, for example in sensing, or implanted biomedical devices, but also in personal electronics. In our group, a nanogenerator was proposed and tested that converts the kinetic energy of an impacting (rain) droplet into electrical energy . Initially, an energy conversion efficiency of up to 2.5% was reported. Later, this efficiency was enhanced to a (theoretical) efficiency of more than 20%. Harvesting this fraction of the impact energy of a droplet should significantly affect the spreading/bouncing behavior of this impacting drop as compared to droplet impact on a regular substrate.
Your research objective will be to quantify the energy dissipation in a droplet-impact powered nanogenerator, or, more specifically, to find out where this energy comes from. You will therefore study the spreading and/or bouncing behavior of the droplet. A first goal would be to make a regime map of whether the droplet jumps of the substrate or sticks onto the substrate after impact, as a function of impact height (energy), both for a nanogenerator and a regular substrate (the nanogenerator in off-state). You will use a high-speed camera to study this. A second step will be to find the droplet-solid contact area as a function of time, translate this to relevant parameters (think of a maximum spreading area, spreading time, retraction time, etc.), and compare these between the nanogenerator and the regular substrate. Depending on you expertise and/or interest, you can either do the required image analysis by hand or by image analysis software (Python/Matlab).
Apart from the standard learning objectives for a bachelor’s project (research planning, academic writing, data presenting, how to work in a lab environment, etc.), you will:
· Obtain knowledge on (the field of) nanogenerators;
· Learn how to fabricate the required samples;
· Learn how to use a high-speed camera;
· Depending on your interests, learn how to analyze images with software.
· Prof. Dr. Frieder Mugele, email@example.com
 Z. L. Wang, Advanced Functional Materials, vol. 18, no. 22, pp. 3553-3567, 2008.
 H. Wu, N. Mendel, D. v. d. Ende, L. Shui, G. Zhou, and F. Mugele, “Physics of electrical generation from drop impacting on charged surfaces," arXiv preprint, 2019.