Prof. Takashi Nakanishi

Abstract

Energy harvesting systems with lightweight, small size, excellent stretchability/deformability, as well as a large and stable power generation would be ideal wearable soft electronic devices applicable for future remote medical systems, healthcare, and robotics applications. For these demands, liquid electrets that possess high deformability, excellent processability, and maintain trapped electrostatic charges in the molecular liquids[1] can be the potential substances. Liquid electrets were developed in which π-conjugated molecules (e.g., porphyrin,[2] C60-fullerene[3])/polymers[4] are wrapped with bulky yet flexible branched-alkyl chains. Interestingly, electrostatic charges are trapped and retained in the liquid. Stretchable/deformable mechanoelectric generators capable of being stretched up to 300% were constructed with those liquid electrets. In addition, the device could adapt the frequencies in the range of the human body motion below 50 Hz.[3-4]

Fig. (a) Chemical structure of alkyl–C60 mono- (1) and bis-adducts (2), and an alkyl-porphyrin (3). Inset photograph is the solvent-free liquid 2 at room temperature. (b) Electrostatic charge density decay of negatively poled liquids 1, 2, 3, and a blank (Nylon fabric) over time after poling. (c) Open-circuit voltage (Voc) characteristics of fabricated mechanoelectric generators with 1, 2, 3, and a blank under continuous vibration at 50 Hz.

References
[1] Tateyama, A.; Nakanishi, T. Responsive Mater. 2023, 1, e20230001.
[2] Ghosh, A.; Nakanishi, T. et al. Nat. Commun. 2019, 10, 4210.
[3] Gupta, R. K.; Yoshida, M.; Saeki, A.; Guo Z.; Nakanishi T. Mater. Horiz. 2023, 10, 3458–3466.
[4] Shinohara, A.; Yoshida, M.; Pan, C.; Nakanishi, T. Polym. J. 2023, 55, 529–535.