Experimental investigation of model reverse electrowetting systems Zaeem Najeeb , Yuan Chen , Jack Dawson, Ehud Haimov, Alexei Kornyshev, Anthony Kucernak Imperial College London, UK Both Yuan and Zaeem will be presenting the poster at separate time intervals. In recent years, ionotronic devices have attracted much attention due to their great potential for applications in energy harvesting. In previous studies, designs based on the effect of double layer charging have been widely explored [1-3]. Several works have proposed systems under the principle of reverse electrowetting utilising electrolytic solution. Those systems are designed to fit into a shoe sole so that electrical current can be harvested simply from walking. This theoretical investigation of new systems was furthered in our recent study, presented in this Faraday Discussion [4], of two proposed, different designs of double layer capacitive-based ionotronic devices. The two designs are, namely, the (i) ‘flat shoe’ design, where a droplet of nonwetting ionic liquid is squeezed between two electrodes, and the (ii) porous sole design, where the nonwetting ionic liquid is being pushed into and out of the pores. Operation of both systems is driven by the periodic pressure exerted on the system while walking. In both cases, the external pressure causes a change in contact area between the liquid and the electrodes, changing the double layer capacitance and thus triggering fluxes of current. The theory predicted promising results with the systems producing power in the order of 0.01 W/dm 2 and 0.05 W/dm 2 accordingly with appropriately chosen parameters. But such systems are yet to be investigated experimentally. The subject of our work was to test those predictions. Therefore, a proof-of-concept study for both the ‘flat shoe’ and ‘porous sole’ design has been carried out with specially prepared electrodes and using 1-butyl-3-methylimidazolium hexafluorophosphate as the electrolyte. We present first results obtained along these lines. References 1. Haimov, E., et al., Theoretical demonstration of a capacitive rotor for generation of alternating current from mechanical motion. Nature Communications, 2021. 12 (1): p. 3678. 2. Kolomeisky, A.B. and A.A. Kornyshev, Current-generating ‘double layer shoe’ with a porous sole. Journal of Physics: Condensed Matter, 2016. 28 (46): p. 464009. 3. Kwon, S.-H., et al., An effective energy harvesting method from a natural water motion active transducer. Energy & Environmental Science, 2014. 7 (10): p. 3279-3283. 4. Haimov, E., et al., Ionotronics for reverse actuation . Faraday Discussions, Manuscript ID: FD-ART-03-2023-000056.R1
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